You Should Fear and Respect the Radula

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Jim has decided that he will join the darkside for the Invertebrate Battle Royale. That’s fine! We wouldn’t want someone with such poor cognitive processes on our team. Jim’s attack centers on the idea that the Aristotle’s Lantern is cooler than the radula.

Now I just cannot stand for this. Especially after reading about how the molluscan radula is deemed one of the reasons this phylum is so cool compared to the echinodermata. I’m sorry, but Craig must not be thinking clearly. The radula? A spiky ribbon makes molluscs cool? Please. Don’t waste your time, Craig. If we’re going to be comparing feeding apparatuses (apparati?) of molluscs and echinoderms, your precious mantle-wearing protostomes don’t stand a chance. Echinoderms utilize one of, if not the, coolest feeding mechanism in the animal kingdom – Aristotle’s Lantern.

You can head over to Jim’s waste of server space to read all about. Let me save you the trouble. Aristotle’s Lantern is just an overly complex (50 skeletal elements and worked by 60 muscles, big deal) structure. The whole thing is just 5 glorified ice-scrappers bound together with a little connective tissue. The function is nothing more than scraping with the exciting part being that it can be used to scrape algae off rocks, scrape dead material off the mud, scrape…you get the picture. For all that complexity all it does is scrape and nothing else.

conus_zahn.jpgThe radula on the other hand…is a design marvel in its simplicity and adaptability. There are seven basic types (with variants on each) that vary in number, arrangement, and structure of teeth: docoglossan or stereoglossan radula; rhipidoglossan radula; hystrichoglossan radula; taenioglossan radula; ptenoglossan radula; stenoglossan or rachiglossan radula; and the toxoglossan radula. Needless to say all this variety allows gastropods to scrap algae off rocks AND feed on detritus AND be predatory carnivores AND be scavengers AND be parasites. Those small holes you find on shells at the shore are from radula of a predatory snail boring through the shell. The snail injects the prey with a digestive enzyme cocktail dissolving the prey within the shell into a prey slurry which is then sucked out…but I digress. Species of the family Conidae can attack ADULT fish with a specially modified radula tooth that serves as a harpoon (right). Echinoderms only relationship to ADULT fish is being their prey.

So again Mollusks are much cooler than Echinoderms.

Dr. M (1620 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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3 comments on “You Should Fear and Respect the Radula
  1. Ok, so the radula is more adaptable than Aristotle’s Lantern, but does that make it cooler?

    You did forget to mention another cool thing about radula bearing molluscs, chiton’s have the most hardcore radula of all. Their’s is coated with the mineral magnetite for super hard teeth! Beat that urchins. But holothurians of genus scotoplanes are still better than either, hands down.

    I want to see members of polychaeta battle it out.

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

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