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.
The 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.