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Palytoxin

This large cinnamon polyp (Palythoa grandis), is feasting on a cleaner shrimp. Somehow, this unlucky shrimp managed to lightly touch the surface of the polyp but it was just enough for millions of nematocysts to harpoon their way into the soft tissues of the cleaner shrimp and hold it tightly. Cinnamon polyps are the larger polyped cousins of members of the order zoantharia, the toxic polyps.  A recent study shows, however, that Palythoa grandis is more toxic than the zoanthids. The name palytoxin comes from the order Palythoa. 

In the figure below, obtained from itis.gov, are results from a recent study on the toxicity of the Palythoa grandis  as compared to species of zoanthid and palythoa species as a whole.  As you can see, the results are remarkable. Palythoa grandis  packs more palytoxin than the famous zoanthids.  Click here to read about one reefkeepers personal experience with palytoxin.

Contrary to popular belief, palytoxin can enter the bloodstream through undamaged skin. When handeling Zoanthids, be sure to wear non-powdered latex gloves. The most common symptoms associated with palytoxin poisoning in humans are characterized by a bitter/metallic taste, abdominal cramps, nausea, vomiting, diarrhea, mild to acute lethargy, paresthesia, bradycardia, renal failure, impairment of sensation, muscle spasms, tremor myalgia, cyanosis, and respiratory distress. Seek immediate medical attention if you suspect that you have been exposed to palytoxin. You may also call the National Poison Hotline  (U.S.) 1-800-222-1222. 

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More on class Anthozoa

Certain corals cannot be placed in close proximity to each other. Some anemones are likely to kill a small fish in your aquarium. If you have ever wondered why, organs called cnidae are to blame. The animals in the phylum cnidaria (nahy-dair-ee-uh-n) are divided into the class Anthozoa (corals and sea anemones) and Medusae (jellies and hydras). They are all defined by their cnidocytes, the primary method for capturing prey. These cnidae function as microscopic weapons which are expelled by the cells in which they are contained and attach to prey. Cnidae can function as harpoons which penetrate and stick, known as nematocysts. They can also function as as a lasso and have a grappling effect which wraps around a projection of the prey, these are referred to as spirocysts.  For the purposes of this blog, we will be focusing on the class Anthozoa, the class belonging to sea anemones and corals.  In later posts, we will touch upon class Medusae.

Any species of coral can have many different kinds of cnidae on itself. If you have ever been stung by a coral, you have personally experienced these cnidae. Most people can walk away from a sting from a regular coral or sea anemone relatively unharmed, but fish and other corals may not be so lucky.

For example, a brain coral (Brain coral is the common name given to corals in the family Faviidae) should not be placed in close proximity to any member of the genus Montipora. The members of the family Favidae can be aggressive towards other corals, if you have brain corals in your aquarium, be sure to provide them with adequate space, strong lighting, and moderate current. 

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Min-Max Anemone

Lastly, the Min-Max, miniature, Maxi, or MiniMax anemone (Stichodactyla tapetum) has been described as being the "perfect anemone" by Coral & Reef Magazine, saying they are "Easy to keep, easy to propagate, and appearing in a rainbow of colors, these little anemones should appeal to many reef aquarists." There has been known to be some confusion about how large they can get. Some only grow to a maximum of two inches (5 cm), while the ones being sold as "Maxi-minis" reach 5-6 inches (13-15 cm).  The small carpet prefers to live on rock work or tucked between rocks and will very quickly move if placed on the substrate.  With adequate lighting and decent flow, these anemones will usually stay in one place. While these tiny anemones are not known to host clown fish, they can attract anemone shrimp and anemone crabs.  In addition, the small carpet is not typically aggressive, but if a careless small fish gets too close, it may be killed and eaten by the anemone. After all, as Nigel (the pelican from Finding Nemo) says, "Fish's gotta swim, bird's gotta eat." Most anemones experience a symbiotic (positive) relationship with organisms known as zooxanthellae (zoo-an-thelly). These unicellular algae donate products of photosynthesis to its host, and the host exchanges them for nutrients which feed the zooxanthellae. Pretty cool, right?

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Duncan Polyps

Now for some information on less scary members of the class anthozoa....

Duncan polyps (Duncanopsammia axifuga), commonly known as Whisker Coral, is another easy coral to maintain.  Like most other LPS (large polyp stony) corals, Dunans need moderate-high lighting to photosynthesize. Compact fluorescent light fixtures, metal halides, T5 high output fluorescent lights, and/or ultraviolet lighting can cater for almost all corals in captivity. Duncan corals also need moderate-high current to bring food (zoo/phytoplankton) to their tentacles. Duncans, and all other members of the Phylum Cnidaria (including jellyfish, hydras, and polyps) posses a stinging or grappling mechanism called a Cnidocyte (NEE-do-cyte) which contains a toxic compound called a nematocyst or cnida (NEE-da). If you have ever been stung by a coral, you have felt the stinging nematocyst. If you have ever touched a coral and felt as if you were physically stuck to it, you have experienced the grappling Cnidocyte. These are the most efficient weapons a coral can have. They are like microscopic harpoons being discharged. Being sessile (stuck to the ground) organisms, they can be very vulnerable to prey. But with weapons such as these, they can properly defend themselves and prey upon small crustaceans and fish.

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Zoanthids

These are just some of the corals and anemones in my 65gal tank at home. Supported by metal halide lamps, these corals thrive in a perfectly mimicked community. Today i will point out some interesting facts about zoanthids (center), duncans, (top & bottom left) and the min-max anemone.  In the following postings, I will feature select species.

Zoanthids (center), which are commonly misspelled as zooanthids, are relatively easy to care for and spread easily on rocks and can even grow on surfaces such as plastic and the pre-filter box that is featured on many large tanks. In this photo, they can be found in the center. But dont be fooled by their simple appearance. Some members of the order Zoantharia produce a toxin called palytoxin. While the concentration of the toxin in these species is hotly debated, if palytoxin enters the bloodstream via an open wound, the result can be fatal. Contrary to popular belief, palytoxin can enter the bloodstream through undamaged skin. When handeling Zoanthids, be sure to wear non-powdered latex gloves. The most common symptoms associated with palytoxin poisoning in humans are characterized by a bitter/metallic taste, abdominal cramps, nausea, vomiting, diarrhea, mild to acute lethargy, paresthesia, bradycardia, renal failure, impairment of sensation, muscle spasms, tremor myalgia, cyanosis, and respiratory distress. Seek immediate medical attention if you suspect that you have been exposed to palytoxin. You may also call the National Poison Hotline  (U.S.) 1-800-222-1222. 

  Photo credit: AG Photo