Echinoderms, Cnidarians, & The Gastropods That Parasitize Them

The recent Invertebrate Wars reminded me of spectacular, but often ignored, group of gastropods. The parasites! This is a group that I have totally geeked out on in the past. In my previous work I have focused on the Ptenoglossa likely a paraphyletic or polyphyletic group, established originally of unspecified rank by Gray (1853). It is generally agreed upon that the group is above the level of family and generally is defined as a suborder (Bouchet & Rocroi 2005). The group includes usually includes the families Cerithiopsidae, Triphoridae, Janthinidae, Epitoniidae, Aclidae, and the Eulimida. Most ptenoglosates possess radulae distinctive to the group (Ponder & Lindberg 1997).

Most eulimids are highly specialized and exclusively ectoparasitic (external parasites) on echinoderms. Most are permanently attached to a single host, although some species may transfer between hosts repeatedly during their lifespan. However a few species have undergone numerous morphological adaptations, including anatomical reductions, to exploit hosts as endoparasites particularly on the sea cucumbers! Shell morphology can be extremely variable, reflecting specialization for parasitism, with males typically smaller than females. Epitoniids are generally considered to be ectoparasites, although some authors have defined this group by various degrees of commensalism and predation (Smith 1998). In contrast to eulimids, epitoniids are exclusively ectoparasitic on cnidarians, primarily anemones and corals, and reside in the sediment near their hosts. A modified radula and jaw are used to bite pieces of their hosts. The host specificity of aclids is less clear is not known. Cerithiopsidae and Triphoridae feed on sponges possibly in a manner that could be construed as parasitic. The Janthinidae, or violet snails, are parasites on the various pelagic Cnidarians like Portuguese Man-’O-War, Porpita, and Velella.

So its obvious once again that Mollusks, specifically Gastropods, are better than cnidarians and echinoderms (capitalization, or lack thereof, is intended)

See below for pictures.


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Janthina globosa feeding on Porpita
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Eulimid on crinoid
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EPITONIIDAE.jpg
Examples of Epitoniids (Wentletraps)
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Eulimid snail on Ophiothrix sp
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Parasitic Eulimid Shell on a Fire Urchin

Dr. M (1606 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, created to facilitate research to address fundamental questions in evolutionary science. He has conducted deep-sea research for 11 years and published over 40 papers in the area. He has participated in dozens of expeditions taking him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses mainly on marine systems and particularly the biology of body size, biodiversity, and energy flow. He focuses often on deep-sea systems as a natural test of the consequences of energy limitation on biological systems. He is the author and chief editor of Deep-Sea News, a popular deep-sea themed blog, rated the number one ocean blog on the web and winner of numerous awards. Craig’s popular writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.





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4 comments on “Echinoderms, Cnidarians, & The Gastropods That Parasitize Them
  1. So, the ability to evolve parasitic lifeforms is a hallmark of superiority? Please, these molls are so pathetically frightened of the ‘real’ world that they have to mooch off others to survive. Sad, how sad.

  2. Pingback: Molluscs, now with 100% more awesum | Deep Sea News

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