#tiny invertebrates and fish larvae

[hopefulqueer]

The eyes vs legs poll has sparked a Pliny-like conversation in this house

[bestanimal]

Round 3 - Actinopterygii - Gymnotiformes

(Sources - 1, 2, 3, 4)

Order: Gymnotiformes

Common Name: “Neotropical knifefish”

Families: 5 - Apteronotidae (“ghost knifefishes”), Sternopygidae (“glass knifefishes”), Gymnotidae (“naked-back knifefishes” and “electric eels”), Hypopomidae (“bluntnose knifefishes”), and Rhamphichthyidae (“sand knifefishes”)

Anatomy: long bodies with elongated anal fin; tapering tails; scaleless; have electric organs capable of producing electric fields to detect prey, for navigation, communication, or attack and defense

Diet: bottom-dwelling invertebrates, fish, caecilians

Habitat/Range: rivers and streams throughout the humid Neotropics, ranging from southern Mexico to northern Argentina; almost exclusively in fresh water (may visit brackish water to feed)

Evolved in: Late Jurassic

(source)

Propaganda under the cut:

The electric organs of most Gymnotiformes produce tiny discharges of just a few millivolts, far too weak to cause any harm to other fish. Instead, they are used to help navigate murky environments, detect prey within sediment, and send signals between fish of the same species. In addition to this low-level field, the electric eels (genus Electrophorus) (image 2) also have the capability to produce much more powerful discharges to stun prey, and shock predators.

Their electrical capabilities of electric eels were first studied in 1775, contributing to the invention of the electric battery in 1800.

Electric eels will continue growing for as long as they live, adding more vertebrae to their spinal column. Some captive individuals have lived for over 20 years.

Vari’s Electric Eel (Electrophorus varii) exhibits greater parental care than the other two species of electric eel. The male makes a nest using his saliva, into which the female deposits around 1,200 eggs for external fertilisation. Spawn hatch seven days later and the mother will keep depositing eggs periodically throughout the breeding season. When they reach 15 mm (0.59 in), the hatched larvae consume any leftover eggs, and after they reach 9 cm (3.5 in) they begin to eat other foods. The male will provide protection for both the young and the nest for up to 4 months.

The Banded Knifefish (Gymnotus carapo) can survive in low-oxygen habitats by breathing air with a modified swim bladder, areas affected by pollution, and for a period on land if its aquatic habitat dries out.

The ghost knifefish species Sternarchogiton nattereri is unique in that its diet consists of freshwater sponges growing on submerged trees, stumps, and other woody debris.

The glass knifefish Eigenmannia vicentespelaea is the only cave-dwelling gymnotiform, and has reduced or absent eyes. As some individuals retain well-developed eyes, this fish may have colonized caves only recently in evolutionary time, and are currently evolving a lack of eyes as an adaptation to cave life.

Neotropical knifefish can lose their tail due to attacks by predators or aggressive encounters other knifefish, but they are capable of regenerating it.

[evolutionsvoid]

In a land of plentiful fluids, there is a great variety of life that thrive within them! Be it water, bile or blood, these fluid bodies are always a host to an incredible array of aquatic creatures!

1. Silt Snorter - A large bottom feeding fish with two mouths and iconic whiskers. They spend their lives down near the silt and muck, using their twin mouths to suck it up and filter food through their hairy gills. Their long whiskers help them keep their bearings when the silt is disturbed and the fluid is clouded. Growing to giant sizes, they are prized trophy fish, but not so great for eating. Their flesh is tainted by their mucky diet, but with the sheer quantity you can get from a single catch, no one wants to waste it, thus folk have developed recipes to help mask the flavor. Also a good source of sea snot.

2. Nailbiter - A keratin clad fish with a dexterous maw. They specialize in pulling prey from nooks and crevices, using their oral fingers to reach in and drag them out. With no actual biting or shearing teeth, they can only eat what can be swallowed whole. Their armored scales are tough but light, allowing them protection while not weighing them down. They are caught for their "fish fingers," a dish made from their oral digits. Legends like to say this fish came to be from a greedy fisherman who reached into the water for one too many fish and had the offending hand taken to replace what he stole.

3. Sperm Eel - An odd boneless fish known for its strange reproductive habits and milky nature. They live in riverside burrows, feeding on small invertebrates and floating bits. The species lives only long enough to reproduce once, as the viable adults congregate up river. When the time comes, these breeding fish straight up disintegrate into reproductive fluids, with the males becoming a cloud of sperm and the females a cloud of tiny eggs. Entire floats of white frothy egg masses form from this breeding session, creating thousands of larvae. This season can clog rivers with these rafts, but it is a bountiful moment for other species that come to feed. When it comes to fishing them, they must be caught and kept alive, as their bodies melt upon death. Though there is no meat to gain, they are used as a soup thickener and add a delightfully milky and salty flavor to a dish.

4. Syringefish - A parasitic fish of the rivers that targets larger piscines or wading beasts. Their single tooth is hollow and built for sucking Blood from prey. Typically look for sluggish fish to feed on, or disturbances from animals swimming. Will ram themselves into whatever flesh they can find and drink as much as they are able. Their stomachs can swell up to fit their meal, growing until they are practically sphere shaped. A pest to any who have to deal with them when wading through the river or trying to catch fish that don't have puncture wounds all over. At least good for a nice bloody snack for those who catch engorged ones.

5. Scabfish - Crimson in color and crusty in texture, they typically appear in bloody waters or in scarred regions. They rest upon the floor of the fluid body, waiting for prey to pass close for an ambush. Their rough scabby skin makes them unappealing to some predators, and make them quite abrasive to handle. Some seafolk may use their dried skin for sanding wood and ivory. Can also be used to make scab crackling.

6. Urolith Fish - A jagged fish that prefers to rest on the bottom rather than swim, using its wide fins to crawl in a way. Typically hides in tight spaces and uses ambush tactics to swallow prey. They are infamous for their spiny bodies. with nasty spikes that break off agonizing shards into those who touch them. Once inside the flesh, they are difficult to remove and are prone to breaking into smaller pieces. These fish serve as a reminder to watch your step when wading through the shallows. To be avoided and not eaten, as their meat reeks of urea. Some shady folk have found their spines good as debilitating knives, stabbed into victims to paralyze them with pain.

7. Mantinia - A colorful creature of chitin that slices through the water with its razor body. Its frontal appendage is designed for lashing out with blinding speed and snaring slippery prey in its barbed grasp. It lacks a true mouth, and instead uses its hollow spines on this "arm" to suck fluids from its prey. Its vivid coloration is believed to be used to win over mates. Despised by fisherman for stealing catches, cutting lines and shredding nets. Legends say that this fish came to life when a warrior surrendered his colorful chitin blade and gave it to the water.

8. Skullcracker - A powerful bulky fish known for its bony forehead and cracking teeth. They feed primarily on ivory corals and other hard-bodied prey, using a mouthful of broad teeth to shatter shells and armor. Their bulging forehead is solid and makes for a good weapon against predators and rivals. They make for dangerous catches, as they may ram the boat with their head or jump from the waters at inopportune times to concuss the unwary fisherman. They have gained this name for a reason.

9. Snot Shroud - A tiny fish that is capable of producing an incredible amount of Phlegm, they use it to surround their body in a false mass. This mucus sheath acts as a fake body and shield, allowing them to ward away parasites and survive predation. This sticky mass also collects food particles and tiny prey for the fish to feed upon. A potent producer of sea snot, and typically kept alive by seafolk on ships to churn out this marine Phlegm for medical purposes.

10. Searfish - A parasitic fish that possesses Yellow Bile and a nasty suction cup on its head. This structure is made to latch onto the sides of larger fish, where it then pumps the burning humor to melt through scale and flesh. The porous surface of this sucker allows it to absorb nutrients from its host, feeding on fluids and digested flesh. Typically target leviathans as their vast size allows them to shrug off these wounds. Circular scorch marks are the scars they leave behind, and some fisherman have found them on the bottom of their boats. If not deterred, they can scorch straight through the floor of a small canoe or boat, thus fisherman take steps to keep the burning buggers away.

11. False Floater - A seemingly rotting fish that plays a deceptive game. Their belly-up posture and patchy skin makes them look quite dead, but this fish is alive and well. A gas filled bladder suspends them in the water, while perfect stillness lures in scavengers. A multi-part jaw filled with needle teeth snares prey that comes to feed on this supposed corpse. Though they are not actually rotting, their meat is very pungent and slimy, thus is avoided when it comes to eating. Their dead appearance does lead to them being associated with the Mother of Snow.

12. Spiretail - A creature instantly recognizable due to their preference of hanging vertically and upside down in the water. They often hover just above the bottom, feeding on the small bits and critters that pass by. Sharp shards of Black Bile jut from their bodies, warding off predators. Often hang out in groups, gaining more protection through numbers. A bane to swimmers who accidentally swim through these schools, as such encounters guarantee several lacerations.

13. Cysthorse - A diseased looking fish that is actually filled with a burning toxin. Attempts to eat or touch them will result in these noxious boils to rupture and seep out this vile poison. Flesh that comes in contact with this fluid often winds up looking like the fish's unsightly skin. Avoided when it comes to fishing as one snared in a net may ruin both the net and the catch with its boiling fluids. Plus, they are associated with sickness, thus their appearance is an omen for future afflictions upon the catcher.

14. Sawtooth - A vicious fish with a killer overbite, they use their protruding blade of teeth to wound and shred prey. Appear to be solitary and not fans of their own kind, judging from the scars their hide often bears. They are a prized catch of any fisherman, though bringing them in without losing the line or a limb is difficult. Their upper jaws are often saved as trophies and turned into tools or weapons.

--------------------------------------------

Recently got and completed the fishing game Dredge and was inspired by it. So the obvious choice was to fill the fluid bodies of FOI with some fishies!

[northerlyy]

Common Watersnake (Nerodia sipedon), juvenile, taken May 22, 2025, in Georgia, US

My first (and hopefully not last) snake of the year: a tiny watersnake! This guy couldn't have been very old. I would actually guess based on his size that he was very recently born! The little creek I found him in will provide a great place to begin life, full of small fish, salamander larvae, and invertebrates for this baby to eat until he's large enough to eat bigger prey and swim long distances.

Unlike most other snakes, N. sipedon is ovoviviparous, meaning eggs develop and hatch inside the mother before being laid, and the mother gives birth directly to baby snakes! Upon being born, these babies are immediately independent and soon leave the mother, who can give birth to—in extreme cases—up to 30 babies!

[thorny-person]

alien food time! Pt 2!

we know why we’re here so let’s get on with it!

1: first up we got eggs! Specifically the different kelp wrapping styles to keep the eggs sealed after cracking the top off to add spices and other desirable ingredients. These will be eaten cooked or raw, when cooked the kelp seal is eaten away then the insides are sliced with a utensil of choice to be eaten out of the shell. When eaten raw the eggs will be shaken up to mix all of the insides together then the seal is removed to pour the mixture out into the open water where it will float in place due to its higher density then the surrounding water, being a perfect side dish to slurp up during a meal.

2: next up is sea eggs, also known as caviar which will be wrapped in kelp to keep all of the tiny eggs together which also helps keeps and fish fry inside as well since they don’t consider it a problem if the eggs your eating hatch since it’ll be eaten along with it.

3: despite appearances these marine sophonts are do in fact eat meat! Specifically they enjoy invertebrates and mollusks! Often packing them into a kelp lunch box of sorts for easy storage of mixed proteins to be used for cooking later on after being prepared for eating.

4: popular fair foods are often different proteins and starches on sticks, either boiled or grilled depending on if the festival is completely underwater or under and above water. The most common being grub sticks, small larvae invertebrates that haven’t deviled touch shells yet so they can be eaten whole without preparation.

5: lastly is various invertebrates in brine! Usually diced or sliced to be marinated and later used in larger dishes if not eaten as is. Very popular in dense soups or as a dressing for salads.

more food in part 3!

[pleistocene-pride]

Kryptopterus vitreolus, known commonly as the glass catfish, the glass cat, the ghost catfish, or the phantom catfish, is a small species of translucent-bodied, social glass catfish in the family Siluridae. It is endemic to the freshwater rivers and streams of Thailand and possibly Malaysia. They are a timid and social species which lives in schools of 6 or more individuals, they are carnivores feeding upon small invertebrates such as insect larvae, worms, tiny shrimps, and zooplankton. Reaching around 2.6 to 3.1 inches (6.5 to 8cms) in length, glass catfish are a small scaleless freshwater-dwelling catfish with two long sensory barbels. Their bodies are transparent because The species' skin is made of a "plywood"-like structure of collagen fibrils, which allows for light to enter and diffract through the muscles. The majority of their organs are located near the head; with a magnifying glass, the heart can be seen beating. When the light strikes this fish at a certain angle, it can create an iridescent, rainbow effect. During acute periods of illness or after death, the tissues turn a milky-white. Additionally the glass catfish possess electroreceptor organs which are extremely responsive to electromagnetic fields, and it is thought they use this in conjunction with there barbells to navigate there surroundings in low light conditions. Little is known about there breeding habits. And under ideal condition a glass catfish may live upwards of 8 years.

[sikariatech]

BOAR FISH - FISHING PROO

BOAR FISH - FISHING PROO

The boarfish, scientifically known as Capros aper, is a fascinating marine species that belongs to the family Caproidae. This unique-looking fish inhabits the temperate and subtropical waters of the eastern Atlantic Ocean, the Mediterranean Sea, and parts of the Indian Ocean. Its distinctive appearance and interesting behaviors make it an intriguing subject in the realm of marine biology.

Boarfishes are renowned for their striking appearance, characterized by a slender, laterally compressed body and vivid colors. Typically, they display a vibrant silvery or pinkish hue, often adorned with iridescent blue or green markings that add to their allure. Their elongated bodies are complemented by a slightly protruding snout and large eyes positioned forward on the head, giving them a curious and distinct facial profile.

These fish are relatively small in size, usually measuring around 15 to 25 centimeters in length, though some individuals can grow slightly larger. Despite their diminutive size, they possess a notable dorsal fin that extends along the back, comprising long, slender spines. These spines, when erected, serve as a defense mechanism against potential predators.

Boarfishes are primarily found in deep waters, often dwelling at depths ranging from 100 to 500 meters, though they can occasionally be seen in shallower regions. They prefer habitats with sandy or muddy substrates near rocky or reef structures, where they can find shelter and forage for food.

Feeding habits of boarfishes primarily revolve around a diet consisting of small crustaceans, zooplankton, and other tiny marine invertebrates. Their feeding strategy involves swimming near the ocean floor and using their specialized mouth to scoop up prey from the sediment or pick it off the water column.

One of the most intriguing aspects of boarfish behavior is their schooling nature. They often congregate in large, loose groups, swimming together in synchrony. This schooling behavior serves multiple purposes, including protection from predators, increasing foraging efficiency, and potential reproduction advantages.

Reproduction in boarfishes occurs through the release of buoyant eggs into the water column, where they undergo development before hatching into larvae. The larvae go through a pelagic stage, floating along ocean currents until they mature into juvenile boarfishes.

Despite their captivating appearance and interesting behaviors, boarfishes generally do not hold significant commercial value in the fishing industry. While they are occasionally caught as bycatch in commercial fisheries targeting other species, they are not a targeted species for human consumption on a large scale.

[jaybug-jabbers]

Vernal Pools & Seed Shrimp Saga

I wanted to record how things went with my seed shrimp (ostracods). I have a thread on Bluesky about it but never posted it here.

In January, I found some seed shrimp in a vernal pool at the park I frequent. They were shades of green and orange.

I caught a small portion in a glass jar and attempted to keep them. After a while I decided to upgrade their living situation to a tiny fish tank I had. The tank had previously been used for isopods but it proved difficult to keep fungus gnats out of that arrangement. So I cleaned it up and set it up for the seed shrimp. It was not furnished with much, just a small sponge filter and a bit of floating cork bark on the surface. I decided the ostracods needed some algae to snack on so I returned to the park to fish some algae out of the vernal pool with a ladle. However I accidentally caught a few stowaways along with the algae. A handful of tiny pollywogs and an iridescent, gold-colored little diving beetle. Here is the tank and the beetle (which briefly grabbed a shrimp pellet)

The beetle was very cool and extremely active but I did not feel confidant in providing it with the proper care, so I released it back to the wild. Meanwhile the pollywogs eagerly chomped away at the algae and also some unknown organic clump I had no idea how to identify. I also saw some kind of larva crawling around in there.

I provided the pollywogs with shrimp pellets, frozen garden peas and fresh spinach. The seed shrimp gladly ate the leftovers. The tadpoles seemed to have no interest in trying to prey on the seed shrimp. I decided to also try buying some algae pellets for the tadpoles, but the pellets were too large for the tadpoles to finish in one sitting and they stunk like the dickens. I had to buy a turkey baster to remove the leftovers which thankfully worked. I fed the algae pellets in smaller pieces after that.

The tadpoles grew quite rapidly and there were more than I initially realized. I had about 15 of them. Their favorite food definitely were the peas. My cat loved to watch them move. It was not long at all before their back legs started to come in.

I had the tadpoles for 20 days in total and they went from tiny little guys to large tadpoles with fully-formed back legs. But it was starting to be difficult to get them all enough food and I knew I was not prepared to take care of these guys all the way to froglets. I did not have the proper setup for them. So I decided to finally let them go.

When I returned to the vernal pool I got them from, it was all but entirely dried up. That means their poor siblings did not fare well. I walked a very short distance away to a similar vernal pool in the same park, so I could release them. I was sad to see them go, they were very fun to have around, but it was the right choice. Perhaps in the future I might learn how to properly rear tadpoles. I wished them the best of luck.

Returning our focus to invertebrates, however! My seed shrimp seemed to be thriving. I am very curious how to explain the different color shells they have. Some are a very pretty moss green, others a very bright orange, some intense black, and others white/pale green. Are they different species? Or does the color have to do with their diet while they formed their shells? (I also definitely had copepods in my tank, and clearly identified some of the female ones.)

Ostracods really are fascinating crustaceans. In my research about them, I found this thread on a discussion form about breeding them, this guide on breeding them, this excellent page about their biology, and a general beginner's guide to IDing various vernal pool critters. Did you know some ostracods are even bioluminescent? Marine ostracods along Taiwan's coastlines can be seen in waves crashing onto shore and are sometimes called Blue Tears. There are also some giant marine species of ostracod in the deep sea, which are very goofy and charming-looking. There are even terrestrial ostracods, although they need to stay damp to survive.

The ones I had were freshwater ostracods, though, of course. They are a very common sight in vernal pools, and extremely hardy creatures, able to survive in some pretty bad conditions. They are scavangers of all kinds of plant and animal-based foods, and not very difficult to please. They reproduce readily and can also lay eggs that can survive drying out and rewetting, like many vernal pool inhabitants. The population I had soon was exploding.

At the very start of March, I was gazing into the large puddles that had formed in the field near my neighborhood after a good rain. There were lots of tadpoles and some seed shrimp, but to my shock I also saw the wispy outlines of something else . . .

Fairy Shrimp! I collected two with a turkey baster. One was female as was evidence by her egg pouch. I believe the other was a little male, due to his face. I placed the pair in my vernal pool tank to observe and hopefully ID. I noticed they were a vivid blue, and they had beautiful red eyes. This identified them as California Fairy Shrimp (Linderiella occidentalis). This is my best photo:

I talked with people on Reddit for a while about these shrimp. Some people encouraged me to collect more of them and start a culture. But I do not feel like I have enough experience with Fairy Shrimp yet to do that. Also, I learned these animals are not like the incredibly hardy and commonplace ostracods. This species in particular is a bit more vulnerable. The species is not formally listed as Endangered or Vulnerable at this time. However, the process of getting a species listed is a long one, and just because an animal is not formally listed does not automatically mean it's safe. I found this website listed the species as 'Imperiled,' a word they are using to mean a species in decline that has no formal protections but probably should have them. I did not want to harm the local population. So I decided against messing with these guys any further.

It is valuable information that they live around here, though. And exciting. It is my hope that the puddles I found them in might be protected. I am not sure how to go about ensuring that, though. They live in a field between two neighborhoods, a piece of land that has been set aside to not be developed (I think), so they may already be semi-safe here. Although kids do run through this puddle with their bikes and I saw a fish net by this very puddle a few weeks ago-- children collecting tadpoles, no doubt. So, it's not exactly safe territory for them. Since they have no formal legal protections, there may not be much I can do for them. If anyone has any ideas, please do let me know. (Additional note: I believe the female dropped eggs the day I placed her in the aquarium. I could try to harvest them from the bottom of the tank and dry them out, as is needed for Fairy Shrimp eggs, but I am not sure if the ostracods would have simply eaten the eggs. And no doubt there are many ostracod eggs down there too, so not sure if this would be helpful.)

In the meantime, my ostracods are thriving in the tank. In fact they are getting downright ravenous. When I put food in there they absolutely swarm it. So at least they're happy.

[koli456]

Hidden Gems of the Water Tiny Fish in the USA

You can think of fishing in the United States as something where you catch large species, such as bass or trout. But just as fascinating is the world of Tiny Fishes in the USA. These little fish species, which are too often ignored, are really important in the health of the water ecosystems. They can truly be enjoyed by the most passionate angler and the best aquarium hobbyist.

Within this post, we will consider some of the most fascinating Tiny Fishes in the USA and highlight their importance to the environment as well as give the reason why they should be on your radar.

The Fascinating World of Tiny Fishes in the USA

The USA is home to a variety of small fish species that are often overshadowed by their larger counterparts. But these tiny fish have much to offer. Here are some of the most interesting Tiny Fishes in the USA:

1. Mosquitofish (Gambusia affinis)

The Mosquitofish is one of the most popular Tiny Fishes in the USA, as these little, hardy creatures are felt to do more for a backyard pond or ditch by getting rid of mosquito larvae. Such small, hardy fish are found throughout ponds, streams, and ditches. Their zeal for eating mosquito larvae has led to them being an inestimable partner in reducing the incidence of mosquito-borne diseases. Several various places have been put in this species for that reason and to keep the local ecosystem in good health.

2. Least Killifish (Heterandria formosa)

One of the smallest fish species in North America, the Least Killifish is another standout among Tiny Fishes in the USA. This tiny fish, typically under an inch in length, thrives in the warm waters of the southeastern United States. Its peaceful nature and small size make it a favorite among aquarium enthusiasts. The Least Killifish is a vital part of its habitat, feeding on small invertebrates and algae.

3. Banded Pygmy Sunfish (Elassoma zonatum)

Known for its striking colors, the Banded Pygmy Sunfish is a beautiful example of the Tiny Fishes in the USA. Found in the southeastern part of the country, this species is often admired for its vivid blue and red markings. These fish prefer slow-moving waters with dense vegetation, making them ideal for nano aquariums. The Banded Pygmy Sunfish’s small size and unique appearance make it a true gem for those interested in aquatic life.

4. Pygmy Sculpin (Cottus paulus)

The Pygmy Sculpin is a rare and fascinating species, found only in a small section of Alabama’s spring-fed waters. It’s one of the most elusive Tiny Fishes in the USA, and because its habitat is so limited, it’s classified as a species of concern. Conservation efforts are crucial for protecting this small fish and ensuring that its unique ecosystem is preserved for future generations.

5. Rainbow Shiner (Notropis chrosomus)

If you’re searching for one of the most colorful Tiny Fishes in the USA, look no further than the Rainbow Shiner. These small fish are known for their vibrant, rainbow-like hues of pink, purple, and blue. Found in clear streams across the southeastern US, the Rainbow Shiner’s colorful display makes it a favorite among aquarium collectors and fish enthusiasts alike.

Why Are Tiny Fishes Important?

While their small size might make them seem insignificant, Tiny Fishes in the USA are actually crucial to the balance of their ecosystems. Here's why they matter:

Pest Control: Species like the Mosquitofish are natural predators of mosquito larvae, helping to control the population of mosquitoes and reduce the spread of diseases like West Nile virus.

Ecosystem Balance: Tiny fish play an important role in maintaining healthy aquatic environments. They feed on algae, detritus, and smaller invertebrates, helping to keep the water clean and the ecosystem balanced.

Food Source for Larger Species: These small fish provide food for larger fish, birds, and other wildlife, contributing to the overall biodiversity of their habitats.

Micro-Fishing: A Fun and Rewarding Hobby

If you're looking for a unique and rewarding fishing experience, micro-fishing is an exciting way to catch Tiny Fishes in the USA. Micro-fishing focuses on using lightweight gear to target small species, offering a challenge that’s both fun and satisfying. This hobby allows anglers to explore the diverse world of tiny fish species and promotes catch-and-release practices to ensure the protection of these fragile creatures.

Protecting Tiny Fishes in the USA

Despite their importance, Tiny Fishes in the USA face threats from habitat destruction, pollution, and climate change. Conservation efforts are essential to ensure their survival. Supporting local habitat restoration initiatives, practicing responsible fishing, and participating in education programs can all help preserve these tiny but vital creatures.

Conclusion

Tiny Fishes in the USA will not always be found in a spotlight, yet define the health of our freshwater ecosystems. These little fish create great sites for requirement controls in pest population, food generation for mammals and birds, and even algae, among others, among the delicate balance of aquatic life. Whether you're an angler or aquarium enthusiast, or someone who just enjoys nature, the time you spend learning about these little fish may end up opening your eyes to a whole new world of aquatic wonder.

For more information visit : fishingproo.com.

[hazeladveturesbelize]

Did you know Barrel sponges (Xestospongia Malta), like many other sponge species, are filter feeders. This means they obtain their food by filtering water through their bodies and capturing tiny organisms and organic particles. Here's a simplified breakdown of the process:

* Water intake: The sponge draws water in through numerous tiny pores (called Ostia) covering its outer surface.

* Filtration: The water flows into internal chambers lined with specialized cells called choanocytes. These cells have flagella (whip-like structures) that create currents to move the water. They also have a collar-like structure that traps food particles.

* Capture and digestion: The trapped particles, which include bacteria, plankton, and other organic matter, are engulfed by the choanocytes and digested intracellularly.

* Waste removal: The filtered water, now stripped of food particles, is expelled through larger openings called oscula.

Essentially, the barrel sponge acts like a living pump and filter, constantly processing large volumes of water to extract the nutrients it needs. This feeding method is highly efficient for capturing small food items and allows the sponge to thrive in nutrient-rich marine environments.

Here are some additional points to note:

* Symbiotic relationships: Some barrel sponges also have symbiotic relationships with photosynthetic bacteria (cyanobacteria) that live within their tissues. These bacteria provide the sponge with additional nutrients through photosynthesis.

* Large volumes: A single barrel sponge can filter thousands of liters of water per day, making them important contributors to nutrient cycling and water clarity in coral reef ecosystems.

* Slow growth: Despite their large size, barrel sponges grow very slowly, with some individuals estimated to be hundreds or even thousands of years old. This slow growth is partly due to their reliance on filtering tiny food particles. They can grow to impressive sizes, sometimes reaching over 6 feet (2 meters) in height and diameter.

*Reproduction:

*Asexual Reproduction*: Barrel sponges can reproduce asexually through budding or fragmentation. In budding, a new sponge grows from the parent sponge and eventually detaches. Fragmentation occurs when a piece of the sponge breaks off and forms a new sponge.

*Sexual Reproduction*: They can also reproduce sexually by releasing sperm and eggs into the water. Fertilization occurs in the water column, and the resulting larvae settle on the seafloor, developing into new sponges.

*Conservation;

*Threats*: Barrel sponges face threats from pollution, climate change, and physical damage from human activities such as anchoring and fishing.

*Ecological Role:

*Water Filtration: Barrel sponges play a vital role in filtering large volumes of seawater, helping to maintain water quality and clarity.

*Habitat*: They provide habitat and shelter for various marine organisms, including small fish, crustaceans, and other invertebrates.

*Nutrient Cycling*: By filtering and consuming plankton, barrel sponges contribute to nutrient cycling in marine ecosystems.

*Conservation Efforts: Protecting coral reefs and marine environments helps ensure the survival of barrel sponges and the diverse marine life they support.

Barrel sponges are truly remarkable creatures, with their unique adaptations and important ecological functions. Their presence in coral reefs is essential for maintaining the health and balance of these vibrant underwater ecosystems

[pradeepnaturalist]

In the stillness of the early morning, the swampy wetlands of India come alive with the soft, buzzing hum of insects, and among the fluttering wings, the Green Marsh Hawk Dragonfly (also known as Orthetrum sabina) stands out. With its translucent wings and iridescent green body, this dragonfly navigates the wetlands, performing an intricate dance between land, water, and air.

Habitat: The Wetlands of India

The Green Marsh Hawk thrives in humid, aquatic environments—particularly in marshes, ponds, lakes, and slow-moving streams. Found primarily in tropical regions of South Asia, this species is abundant in the wetlands of India, Sri Lanka, Nepal, and Bangladesh. The habitat is characterized by lush vegetation along the water's edge, tall grasses, reeds, and a mix of open spaces for sunbathing and shaded areas for resting.

The Green Marsh Hawk prefers places with still or slow-moving water, where there is plenty of plant life to hide in, both for hunting and for laying eggs. These wetlands also teem with life: from tiny aquatic invertebrates to larger insects, fish, and amphibians, providing a rich ecosystem for a dragonfly's survival.

The Life Cycle of the Green Marsh Hawk

The life cycle of the Green Marsh Hawk, like most dragonflies, begins in the water. It goes through several distinct stages: egg, larva (nymph), pupa, and adult.

1. Egg Stage

The journey of a Green Marsh Hawk begins when the female lays her eggs in or near the water. This is often done in the early morning or late afternoon. The eggs are deposited on submerged vegetation or in the water's surface, where they hatch after a few days to weeks, depending on environmental conditions like temperature and water quality.

2. Nymph Stage (Larval Stage)

After the eggs hatch, the dragonfly enters its nymph stage. The nymphs are aquatic and can remain in the water for several months to several years, depending on the species and the environmental conditions. During this time, the nymphs are voracious predators, feeding on a wide range of small aquatic creatures like tadpoles, fish larvae, and even smaller invertebrates such as water beetles and mosquito larvae.

Green Marsh Hawk nymphs are typically brown or grey, camouflaged in the muck and mud of the wetland floor. They are skilled hunters, using their extendable lower jaw (labium) to snatch prey with incredible speed, much like a frog’s tongue. During this stage, the nymph grows through multiple molts (shedding its exoskeleton), each time becoming larger and more formidable.

3. Emergence and Pupal Stage

After a period of growth, the nymphs reach the final stage of their aquatic life cycle. The nymphs will crawl up the stems of submerged plants or the muddy banks of the wetland. At this point, they will molt one last time, emerging from their nymphal exoskeleton as winged, adult dragonflies. This emergence typically happens at dusk or dawn, when the air is still and the temperature is cooler.

The newly emerged adult is initially soft and vulnerable, but it soon dries its wings in the warm sunlight. Over the next few hours or days, the exoskeleton hardens, and the dragonfly’s wings become strong and functional. This is known as the exuvia, or the discarded nymphal skin, which can sometimes be found near the edge of the water, marking the point where the dragonfly completed its transformation.

4. Adult Stage

Once fully developed, the Green Marsh Hawk takes to the air, its green and black body glimmering in the sun as it zips across the water's surface. The adult dragonfly's primary role is reproduction, but it also plays an essential role in controlling insect populations. It feeds on smaller flying insects, including mosquitoes, midges, and smaller flies. Its excellent aerial skills allow it to hunt with precision, darting and hovering to catch its prey mid-flight.

In the air, the Green Marsh Hawk is a skilled flyer, capable of rapid acceleration, sudden changes in direction, and hovering in place to capture prey. The dragonfly's large, multifaceted eyes give it nearly 360-degree vision, making it an efficient hunter. Males are often seen patrolling specific territories over the water, where they will engage in territorial disputes with other males. These territorial displays often involve aerial battles, where the males chase each other through the air, trying to establish dominance.

The female Green Marsh Hawk lays her eggs in or near the water once again, and the cycle begins anew.

The Role in the Ecosystem

The Green Marsh Hawk plays a crucial role in its ecosystem. As both a predator and prey, it helps maintain a balance in the population of smaller insects. It preys on mosquitoes, midges, and other flying insects, which helps control the populations of potential pest species, contributing to the overall health of the wetland ecosystem.

The Green Marsh Hawk's presence is also an indicator of the health of the wetland habitat. Like many dragonflies, they are sensitive to changes in water quality and pollution levels. A decline in their numbers can often signal changes in the water’s health, whether due to pollution, habitat destruction, or climate changes.

Adaptations for Survival

The Green Marsh Hawk is a beautifully adapted predator, well-suited for life in the wetlands:

Aerial Skill: With its long, slender body and large wings, it is an agile flyer. It can hover in place, dart quickly in any direction, and pursue prey with accuracy, making it a fearsome hunter in the air.

Vision: Its compound eyes give it a nearly panoramic view of its surroundings, allowing it to spot prey from far away. This exceptional vision also helps it avoid predators and navigate the dense vegetation of the wetlands.

Breathing System: The nymph’s ability to extract oxygen from the water through specialized gills located in its abdomen is a vital adaptation for life in the aquatic environment.

Camouflage: Both the nymph and adult have camouflage that helps them evade predators. The nymph blends into the muddy, aquatic environment, while the adult’s green body often merges with the aquatic plants and reeds, making it less visible to larger predators like birds and fish.

The End of the Cycle

As the Green Marsh Hawk nears the end of its life, the adult dragonfly will begin to slow down, no longer engaging in territorial fights or chasing after prey as actively. The dragonfly's lifespan is relatively short, typically only a few weeks to a couple of months, depending on environmental conditions.

Once its reproductive duties are complete, the dragonfly will die, its body returning to the ecosystem, feeding other creatures, and enriching the soil. The cycle begins again with the next generation of nymphs, ensuring the survival of the species.

The Green Marsh Hawk, with its iridescent wings and delicate yet determined nature, is a symbol of the vibrant life that exists in the wetlands. From the stillness of the water to the swift dance of its flight, it embodies the delicate balance of life in this ever-changing, ever-living ecosystem.

[intolerable-lolly]

Moths have hairs on their feet that are small enough to interact with Van der Waals forces, which is like molecular gravity. Basically, they use quantum physics to help them stick to surfaces! Some moths stick to surfaces with sticky secretions, too, but I feel like that's a little less cool than having hairs small enough to get pulled into the electrostatic field of an atom or a molecule.

The whole family of Lepidoptera is also ridiculously strong, too, in relation to their body size. They have to be, in order to fly!

As for sea cucumbers, hoo boy do I have a ramble for you! So, okay, sea cucumbers can puke up their guts to distract predators, that's one fact. They can also regrow from being split in half, like a worm, and their intestines regenerate over time!

That orifice they use to expel their intestines is basically their one multi-purpose mouth/anus/reproductive passage, actually. Like sea urchins, sea cucumbers use external fertilization to reproduce -- they expel eggs or sperm (depending on sex) into the water, and if the two come into contact, hooray! Sea cucumber babies! Not sure about how their juvenile stages work, but for sea urchins, their growth only actually begins when they settle on a surface. If it takes too long for a sea urchin larva to settle, they die. Maybe sea cucumbers are similar? I dunno.

But the thing about sea cucumbers that's extra fascinating and kinda gross is the parasitic relationship that they have with pearlfish. Pearlfish are tiny, scaleless little fish that generally just live in invertebrates. For example, oysters. Some species parasitize sea cucumbers, though. They don't eat the sea cucumber, but they use the sea cucumber for shelter, and when the sea cucumber expels its internal organs to fight back against predators, they are expelled, too. Obviously, ick, but pearlfish do this because they are literally transparent. You can see their intestines. They're also really small, so they are entirely vulnerable. Gross, but weirdly sensible???

That's my list of sea cucumber facts (with cameo from moth magnetism)! I use those puppies when I'm out of the house and someone walks up to try and get my number or whatever. Depending on my level of apathy that day, they could be shared with a manic gleam in my eye and the phrase "hey, do you want to know facts about sea cucumbers?" OR a dead-eyed stare and the immediate listing of them en masse...

Poke poke

I have a series of weird facts about sea cucumbers, if you want to hear them. I also know some cool stuff about moths and van der waals forces, too.

Ooh. I know about how cucumbers puke up their guts to distract predators, and a few cool things about moths, we should see if there's overlap, but I forget anything I've been told about Van der Waals forces.

[crevicedwelling]

Hey! This might be a kind of stupid (or insensitive) question but I was wondering about mosquitos. I’m actually pretty chill with most insects but they bite, spread diseases and a whole host of other things. I know there are a lot of scientists working right now to reduce mosquito fertility rates which I’m broadly supportive of, but I’m not sure what the unintended consequences are. Like….. would we as a species be okay if mosquitos were eradicated?

it’s entirely a valid question, and a point I hear raised a lot. the answer depends on on how far-reaching your question was intended to be:

an important thing to understand is that there are over 3500 species of mosquito, and of those, only 88 are known to transmit diseases to humans, with about 200 more that potentially could become human disease vectors (Yee et al.) most mosquitoes drink nectar—both males and females—but females typically (but not in all species/forms) require a blood meal from mammals, birds, reptiles, amphibians, or even other arthropods and invertebrates.

if all mosquitoes were “eradicated,” there would undoubtedly be some very bad effects on the environment, although in the utmost selfish view I’m not fully sure how long they’d take to affect humans.

many plants are pollinated by small flies (like cacao! you can thank biting midges for all your chocolate) and certainly some only by mosquitoes. mosquito pollinated plants likely include many in tropical rainforests, where mutualisms between tiny, unusual species are very common, and oddly enough in the Arctic, where soggy summers create a whole lot of mosquitoes.

likewise mosquitoes are likely an important part of the diets of many bats, birds, spiders, dragonflies, other flies, and fish that might eat the larvae, among many others (including mosquitoes that eat other mosquitoes as larvae, like the beautiful Toxorhynchites). the negative effect on these animals in turn could affect their predators, or all the other ecosystem. if all mosquitoes disappeared, there would probably be significant upheaval across global environments, although I don’t know enough to say exactly what the end result would be. making all mosquitoes go extinct would be a very bad idea though, so it’s a good thing humans have no reason or capability to do that.

but people probably don’t have the 3,000 other mosquitoes in mind when they’re trying to control the flies, it’s that 88 to 300-ish bunch that bite humans and transmit diseases. first off, any genetic/sterility control method that targets non-native mosquitoes is most likely to have only good effects. non-native mosquitoes are reduced, people are bitten less. good on both counts. (it’s still possible certain things might be upset, such as if native species have adapted to use non-native mosquitoes, or if the non-native ones were outcompeting some even worse species. don’t know enough to say.) In many places, this is precisely what’s happening, with Aedes being sterilized, modified, or infected with bacteria that cause some reduction in offspring where it is invasive.

as for eradicating mosquitoes in their native range… it gets a bit tricky. I’m not enough of an ecologist or mosquito biologist to give a clear answer here. I also don’t know if there’s consideration of using control methods like you mentioned on species in their native range.

your question was about making mosquitoes go extinct, though, so I’ll focus on that.

would losing a few species of mosquito that are particularly dangerous to humans result in ecological upheaval? I don’t know. ecology is vastly complicated and when people make big decisions involving pests, we can often make problems way worse, like all the times a predator was introduced and started killing off things we didn’t think they would (this has happened with mosquito control, by the way). extinction only goes one way. I’d say in a hypothetical situation where I could just *poof* away an entire mosquito species, I probably wouldn’t do it. we just don’t know enough about the world yet to make decisions like that.

that’s not to say there aren’t ecologically and human-friendly ways to solve the issue of mosquito-borne disease—reduction of manmade breeding pools, careful biological control, targeted, safe pesticides—and maybe in some cases, sterilization or genetic control are part of the solution. but if it comes down to extinction or not, we’d better consider things very carefully before swatting at entire species without knowing what might happen after.

some of the links to the articles I used to research a bit for this post. read them if you'd like, they're fascinating!

[uncharismatic-fauna]

A Striking Salad of Sea Cumbers

No, they’re not a vegetable-- sea cucmbers make up the class Holothuroidea, which is a member of the echinoderm family-- invertebrates which also include star fish, sea urchins, and sand dollars. There are about 1,700 species of sea cucumber found on the ocean floor, in open water, and in coral reefs. These invertebrates are found all over the world, but the greatest variety of species can be found in the Asian Pacific, in reefs around Southeast Asia, Indonesia, and eastern Australia.

While they are invertebrates, sea cucumbers do have an internal skeleton: a structure made of tiny calcified branches called ossicles that are joined throughout the skin by connective tissue. Some species enlarge their ossicles to form hard plates, which can protect them from predators. Outside this common feature, sea cucumbers can take many forms. The stereotypical sea cucumber has a cylindrical body, often with bumps that resemble warts. These bumps have important functions ranging from locomotion to feeding, and in some species the bumps are elongated into tentacles. Most species also posses five pairs of tube-like feet. Outside the stereotype, however, members of the Holothuroidea class can take many forms, ranging from perfectly round to worm-like, and with many variations on appendages, location, and predatory defense. The average sea cucumber species range from  10 to 30 cm (4 to 12 in), but again there are many exceptions to the rule.

Holothuroidea has a relatively simple anatomy: a mouth, leading either to a stomach or the intestines, which empty into the anus. The anus is also used to filter oxygen from the surrounding water. As a defense mechanism, sea cucumbers may expel their organs through their anus when startled, and regrow them later. Other discharge a sticky mucus that ensnares predators. Many are toxic, and use bright colors and large appendages to warn potential predators away. However, some fish such as pufferfish, crustaceans, and large mollusks, have been known to make a meal of sea cucumbers when few alternatives are available. In turn, sea cucumbers feast on debris, plankton, and decaying organic matter. Most do this on the ocean floor, but some are able to swim or even ‘jump’ up to 1000m before floating slowly back down.

Like most echinoderms, sea cucumbers are not social; they largely ignore each other when they happen to occupy the same space. Different species can reproduce sexually, asexually, or both, and do so throughout the year. Most simply release thousands of sperm or ova into the open water, and these drift through the ocean until they combine to make a fertilized egg. The egg takes only three days to develop into a free-swimming larvae called the auricularia stage. Next is the doliolaria stage, in which the body enlongates and settles on or near the ocean floor. The last stage is the pentacularia, in which tentacles and tube-feet emerge. Once these features have finished growing, usually in a few months to a year, the sea cucumber are ready to reproduce. 

Conservation status: Because of the large number and distribution of sea cucumber species, their status ranges from Not Threatened to Endangered. Their primary threat is over-harvesting for medicine or food. Many species on coral reefs are also threatened by habitat loss.

If you like what I do, consider leaving a tip or buying me a ko-fi!

Photos

White teatfish sea cucumber (Holothuria fuscogilva) by Steve Purcell

California sea cucumber (Parastichopus californicus) by Gerald and Buff Corsi

Transparent sea cucumber (Pelagothuria natatrix) by Larry Madin

Chocolate chip sea cucumber (Isostichopus badionotus) by NOAA

Leopard sea cucumber (Bohadschia argus) by Leonard Marks

Sea cucumber (Kolga hyalina) by Bodil Bluhum

[evolutionsvoid]

Visiting tropical waters pretty much guarantees you will see plentiful and colorful wildlife. The waters themselves host an endless amount of species, especially around the coral reefs! Such incredible ecosystems! Such beautiful colors and structures! The vast coral reefs and their countless inhabitants is one of the things that makes me curse my weakness to saltwater! What sights I am missing! Oh it makes me even greener with envy when I see humans frolicking about in the ocean and diving down to witness these grand ecosystems! What I wouldn't give! At least I am not completely excluded from seeing the wonders that live below, as sometimes the beauty of the ocean comes crawling up onto shore! The tachyzoa even seem to bring a part of the coral reef with them! Tachyzoa are semi-aquatic mammals that are found on tropical coastlines, with a focus on places that have thriving coral reefs. They should be very easy to identify, what with their vibrant colors and spiny look! The tachyzoa are sometimes referred to as "swimming anteaters" or "anteater seals" by some folk, which kind of sums up their general anatomy. Elongated pointed snout with a long tongue to boot, while its clawed limbs have turned to flippers. Upon their back are hefty keratin plates serving as armor, which are further enforced by the sharp branching spines that erupt from them! To add to this look are the colors, where their fur is almost as pale as beach sand and their armored bits hued with pinks and purples. Like I said, it is like they are carrying a coral reef on their backs! However, it should be noted that this is not actually coral, as I can't imagine a lot of coral species doing well with the constant switching between land and sea. Instead these spines are made from a collection of specialized hairs that are further reinforced by keratin. These multiple strands bunch together at the base, then fray and break apart as they go up, which gives the branched look for each spine. It is a wonderful look, which is both protective and deceptive when its time for them to go diving!

This species spends most of its life in the ocean, diving down to the coral reefs to hunt for food. While there are no ants or termites to slurp up in the ocean, there are still a whole lot of invertebrates to be found! Shrimp, worms, fish eggs and larvae can be found hiding amongst the rock and coral, and the tachyzoa uses its long snout and tongue to reach them. They locate prey with both eye sight and their sensitive snout, but I don't mean by smell. They seem to have some kind of tiny sensitive hairs at the very tip of their nose/mouth, which help them feel around whenever they reach into cramped places. When their mouth is stuck into some burrow or crevice, they can't see what is inside, so these hairs help them differentiate between rocks and food. If their sensors tell them its food, the tongue lashes out to lick them up. Since they are underwater, sticky saliva doesn't really do the trick, so instead their tongue is coated in tiny barbs. They hook onto shell and flesh, then pull them into the waiting mouth. It should be noted that the Tachyzoa is a mammal and thus cannot breath underwater. They need to go back to the surface to get a breath of air from time to time, which for them is like every thirty minutes. The tachyzoa has learned how to really hold its breath! Its long snout also acts like a snorkel when they are close to surface, reaching up just enough to get that breath and dive back down. When underwater, their nostrils clamp shut to prevent water from getting in, and their lips keep a tight seal that lets the tongue go out but still keep out water. The ocean provides tasty food, and the land provides a nice haven to rest. After filling their bellies and the sun begins to set, the tachyzoa retreat from the deep and head to shore. The night brings out new predators in the ocean, and a day of swimming and diving has left them tired. Tachyzoa are not completely defenseless, as their spines have an extra bite to them. Due to their diet, they collect a variety of toxins and need a place to put them. Their body directs these poisons to their spiny hairs, where pores pump the nastiness into these twisted spires. Getting jabbed by one or more of these spines will cause a burning pain to develop around the wound, sometimes affecting the whole limb. Some have described the feeling like being lit on fire or dunked in acid, and the agony can last for hours. Combine it with their armor plating, and many predators hesitate to take a bite. That is if they even find them, as their colors and shape help them blend in with the surrounding coral! However, nighttime means poor visibility for the tachyzoa and resting on the water's surface means leaving your vulnerable stomach exposed. So instead they flee to the beach, where they awkwardly climb up onto the shore and bury themselves in the sand. All that remains exposed are their toxic barbs and the very tip of their snout, which gets the occasional breath as they slumber below. When the sun arises the next day, they emerge and rush back into the ocean.

Despite them being mammals, tachyzoa actually lay eggs, belonging to a rather rare group. When the nesting season comes, the females will go to the sandy beaches to lay their eggs. A hole will be dug in the sand, the eggs deposited and then the mother positions herself atop of them. She will bury herself in the sand with them, using her own body and spines as a shield against predators. The surrounding sand and her body will keep them warm, until the day comes where they hatch. During this whole time, the mother will not eat a thing, living off the fat she has built up for this occasion. When the little puggles hatch, they will climb into her pouch and suck up the milk she secretes from her pores. With her babies on board, the mother tachyzoa will return to the ocean to finally get something to eat. While she is fine with the water and swimming, the puggles are not. Thankfully, the species has developed a muscle lined pouch that allows her to seal it shut to prevent water from getting in. The puggles are born with the ability to hold their breath, which they do so as they remain sealed into this air bubble of a pouch. The mother will take much shorter, shallower dives, moving fast to gobble up food and return to the surface. When she reaches the water's surface, she will flip onto her back and expose the pouch, opening it up so air can flow back inside. They will live like this for two months, until the puggles start to develop their own spines and armor. When that happens, they are taken to land and left in burrows. The mother will return to them each night so that they still have her milk. Eventually they will get the strength and armor to crawl out on their own and at last enter the coral-filled sea.         The tachyzoa is a beloved species in the coastal communities, as many find them cute and charming. Their colors are impressive and their daily migration from land and sea is something that always garners an audience. Though their diet makes their flesh poisonous, they are hunted for their waterproof fur and spectacular armor. Thankfully, this practice has been in decline for the past couple of years, as their harvest has been deemed illegal and better alternatives for these materials have arisen. I do know some kelp dryads will snap off a few spines from diving tachyzoa to use for spear tips and hunting weapons, but they don't actually kill them. Efforts have been made to preserve shorelines where these mammals rest each night, and these places become off limits to visitors and traffic when the nesting season begins. Their adorable look has made people consider them for pets, but their lifestyle makes this pretty much impossible. They need the ocean to function, as they won't even eat when presented with food on dry land. They are so used to hunting for their meals, that they don't seem to comprehend a free lunch. Besides, this species spends most of its life in the ocean, what are you even going to do with it?! Again, thankfully these efforts have been failures and I don't have to suffer people owning these animals who clearly shouldn't be having them. I mean, I won't lie, they are pretty dang cute! It would be quite magical to dive down to these coral reefs and see them swimming about! BUT I CAN'T! ARGH!   Chlora Myron Dryad Natural Historian

-----------------------------------------------------

“Tachyzoa”

Alrighty, here is another water-based creature that isn't some abyssal nightmare! Originally thought I was so clever for turning echidnas into water critters, but further research is showing that folks think that echidnas did originally have a water dwelling ancestor, so this isn't all that big of a stretch. Oh well!

[dougdimmadodo]

Atlantic Cod (Gadus morhua)

Family: Cod Family (Gadidae)

IUCN Conservation Status: Vulnerable

Native to the northern Atlantic Ocean, Atlantic Cods live in large shoals that may contain more than 10 million individuals, with larger, stronger individuals swimming ahead of their smaller travelling companions to determine the direction the shoal swims in and “scout” for predators such as Greenland Sharks and Orcas. Growing to be 68-130cm (27-51 inches) in length, adult Atlantic Cod are safe from all but the largest predators (particularly while in shoals) and may live for over 20 years. The diets of individuals of this species vary considerably depending on their size and maturity: large individuals (such as those that act as scouts) feed on moderately sized fish such as Atlantic Haddocks, Common Soles, Atlantic Mackerel and (on rare occasions) juveniles of their own species, while smaller individuals feed on smaller fish and marine invertebrates such as squids, bivalves, starfishes and sea cucumbers - regardless of size, food is mainly found using the single goatee-like barbel (a sensory organ that detects chemicals released into the water by prey) which protrudes from the front of the lower jaw. Many populations of Atlantic Cod are migratory and return to specific spawning grounds to reproduce each year; after arriving at a spawning ground, numerous males will circle around mature females while producing drum-like booming noises and fighting off smaller rivals in an attempt to impress the female, and upon successful courtship a female will produce clusters of several million tiny gelatinous eggs which will be fertilized externally by a male of her choice before being carried away to coastal environments by the tide. Most of these eggs will be eaten or otherwise die before they are able to hatch, but those that survive will hatch into tiny plankton-eating larvae which slowly grow into coast-dwelling juveniles before reaching maturity at around 2-4 years of age and travelling further from the coastline in search of a shoal to join. Atlantic Cods are regularly caught and eaten by humans, and while this has led to extremely concerning declines in the species’ population there is a potential for increased legal protection of wild Atlantic Cod (particularly those found at their spawning sites) and a higher reliance on farmed individuals for food (thus reducing the impact on wild populations) to give this species a chance to recover.

--------------------------------------------------------------------------  

Animal Advent Calendar - Day 19

Image Source: https://www.inaturalist.org/taxa/63740-Gadus-morhua