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Family #2: Agelenidae

Agelenidae sp. Photo by Shyamal, CC BY-SA 3.0

These are commonly known as funnel web spiders or grass spiders. Keep in mind, however, that they are different from the infamous Sydney funnel web spider, which belongs to an entirely different infraorder and is known to have medically significant venom. Agelenids, on the other hand, are harmless creatures that you can frequently find living in grass, window sills, bushes, and more.

Where the "funnel web" gets its name is somewhat self explanatory. The web has a small, cylindrical retreat which expands out into a sort of sheet. The spider will sit in the smallest part of the funnel, the retreat, until it senses the vibrations of prey on the sheetlike section of the web. At that point, it will run out with lightning speed and take down the prey, pulling it into the retreat.

Agelenopsis sp. Photo by Philip Cohen, CC BY-SA 2.0

As you can see, agelenids have impressively long spinnerets. Specifically, the distal (farthest out) segment of the spinnerets is exceptionally long. A lot of people mistake these for wolf spiders, but if you see the long spinnerets, you can be sure that it's actually an agelenid!

Something fascinating about agelenid webs is that they're not sticky, like you might expect a spider web to be (some orb webs are sticky, but it depends on the type of orb weaver!). Rather, these webs rely on a dense meshwork of threads to entangle their prey long enough for the spider to run out and grab it.

Agelenidae is an extremely broad-ranging family, found on all continents except Antarctica. There are currently 94 recognized genera and a whopping 1380 species!

Information sources can be found below the cut:

World Spider Catalog (2023). World Spider Catalog. Version 24. Natural History Museum Bern, online at http://wsc.nmbe.ch, accessed on {date of access}. doi: 10.24436/2

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The Spider Guide's Master List of Links

My main website (Better with Bugs)

Learn spider anatomy (link coming soon)

Learn other spider terminology (link coming soon)

See the families I've covered so far!

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A (Very) Brief Overview of The Spider Tree of Life

Let's start with the basics. All spiders fall into the following classification, from least to most specific:

Kingdom: Animalia (animals - cannot produce their own food, can move voluntarily, and are multicellular) Phylum: Arthropoda (animals with jointed exoskeletons made of chitin) Subphylum: Chelicerata (chelicerates - possess feeding appendages called chelicerae) Class: Arachnida (arachnids - eight legs with an additional pair of appendages, fused head and thorax, and several more unique traits) Order: Araneae (spiders - chelicerates that possess spinnerets for silk production, and have special male copulatory organs that we'll get into some other time)

Okay, so we've reached the clade that includes all spiders: Araneae. This is the order level. Just below order, spiders have a level called the suborder ("sub" meaning "under"). Here, spiders split into two suborders: Mesothelae and Opisthothelae.

Mesothelae is an incredible group of spiders with only a few extant (non-extinct) taxa. The defining characteristic of its members is an abdomen that's segmented by plates called tergites. This is a trait that was also present in the ancestors of spiders, so we may consider the Mesothelae to be "primitive" since they possess ancestral traits. All other spiders (the Opisthothelae) have abdomens that are fused into a single unit, which is the derived (non-ancestral) trait.

Heptathela higoensis, a member of the suborder Mesothelae. Photo by Marshal Hedin

Okay, so now we know the two suborders of spiders: Mesothelae (the "primitive" segmented spiders) and Opisthothelae (the non-segmented spiders). But we're not done yet! Opisthothelae divides into two infraorders ("infra" meaning "below" or "further on"). These infraorders are Mygalomorphae and Araneomorphae.

Mygalomorphae shares some common features with the Mesothelae - namely downward-facing chelicerae (mouthparts) and two pairs of book lungs (meaning four total). The araneomorphs, however, lack these ancestral features, instead sporting chelicerae that move in from the sides (causing the fangs to appear horizontal or "cross-acting") and fewer book lungs (only one pair or even zero!). Most araneomorphs also have tracheal systems, not unlike insects and myriapods (though the spider tracheal system evolved independently!).

Left: Atrax robustus, a mygalomorph with downward-facing chelicerae (photo by Tirin). Right: Cheiracanthium punctorium, an araneomorph with cross-acting chelicerae (photo by Rainer Altenkamp).

Finally, within the infraorders Mygalomorphae and Araneomorphae exist a myriad of diverse spider families. Araneomorphae is by far the more speciose and diverse of the two, but they both have their own unique charms. As of April 2023, there are a whopping 132 spider families recognized!

Follow for future posts about the many different families of spiders!

Information sources can be found below:

Coddington, Jonathan A. & Levi, Herbert W. (1991). "Systematics and evolution of spiders (Araneae)". Annual Review of Ecology and Systematics. 22: 565–592. doi:10.1146/annurev.es.22.110191.003025. JSTOR 2097274. S2CID 55647804.

Scientific name: Opisthothelae in Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. http://taxonomicon.taxonomy.nl/. Access date: 8 December 2010

Song, D.X.; Zhu, M.S. & Chen, J. (1999). The Spiders of China. Shijiazhuang, CN: Hebei University of Science and Technology Publishing House. ISBN 978-7-5375-1892-5.

Wheeler, W. C., Coddington, J. A., Crowley, L. M., Dimitrov, D., Goloboff, P. A., Griswold, C. E., … Zhang, J. (2016). The spider tree of life: phylogeny of Araneae based on target-gene analyses from an extensive taxon sampling. Cladistics, 33(6), 574–616. doi:10.1111/cla.12182

World Spider Catalog, 2023. Natural History Museum Bern. http://wsc.nmbe.ch, version 24.0 [accessed 30 April 2023].

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Family #1: Actinopodidae

Pictured: Male Missulena occatoria. Image by Peripitus

Actinopodidae is a family of mygalomorph spiders, meaning they are a "primitive" group, sharing many physical traits of the oldest, most ancestral spiders. They are commonly known as mouse spiders, and can be located in both Australia and South America.

They build trapdoors rather than webs to hunt, snatching prey that wander too close to their dens. Some have beautiful red coloration on their carapace (head) and/or chelicerae (mouthparts), like this pictured male Missulena occatoria.

A fun fact about actinopodids is that some exhibit a behavior known as ballooning - in which the young spiderlings throw out a line of silk from their spinnerets and let it carry them into the air as a dispersal method. This is unusual to see in a mygalomorph, because they are generally more stout-bodied and heavy than their araneomorph counterparts (more on mygalomorphs vs araneomorphs in a future post!).

Actinopodids are not considered dangerous spiders. A 2004 study on the effects of their bite reported that while it is certainly quite painful, the very worst systemic affects appear to be headaches and possible nausea. If you were to ask my opinion, I suspect the large fangs, rather than the venom, are what causes the majority of the pain!

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Peer-reviewed sources can be found below:

General info:

Greenberg MR, Huey JA, Framenau VW, Harms D (2021) Three new species of mouse spider (Araneae: Actinopodidae: Missulena ­Walckenaer, 1805) from Western Australia, including an assessment of intraspecific variability in a widespread species from the arid biome. Arthropod Systematics & Phylogeny 79: 509–533. https://doi.org/10.3897/asp.79.e62332

Ballooning behavior:

Ferretti, N., Pompozzi, G., Copperi, S., & Schwerdt, L. (2013). Aerial dispersal by Actinopus spiderlings (Araneae: Actinopodidae). Journal of Arachnology, 41(3), 407–408. doi:10.1636/j13-27.1

Bite Effects:

Isbister, G. K., & Gray, M. R. (2004). Bites by Australian mygalomorph spiders (Araneae, Mygalomorphae), including funnel-web spiders (Atracinae) and mouse spiders (Actinopodidae: Missulena spp). Toxicon, 43(2), 133–140. doi:10.1016/j.toxicon.2003.11.009