|Image: California Academy of Sciences|
We've already seen ONE way in which molluscs take on the worm's lifestyle. Aplacophorans were molluscs who dropped their shell, became longer and thinner, and took to burrowing underground or wrapping themselves around corals.
Worm Snails are different. It turns out you don't actually have to get rid of your shell to live like a worm!
|Image: Natural History Museum Rotterdam|
There are about 150 species of these marine snails around the world, all in a family called Vermetidae.
Vermes is Latin for "worm". Isn't it odd how it just looks like a German (or Indian) mispronouncing "worms"? Also it's where "vermin" comes from.
|Image: Chad King (SIMoN / MBNMS)|
A snail shell unlike any other
|Image: Ria Tan|
There are two ways for a Worm Snail to feed. One is to simply filter edibles out of the same water they take in to breathe. This is much like those other molluscs, bivalves like mussels and scallops. Others do things differently. It's our old friend the mucus net!
Video: Daragh Owens
Sea Butterflies and Fat Innkeeper Worms also feed with a mucus net. Nice to see it in action!
Mucus is an abundantly available, theoretically edible, bio-degradable resource, so Worm Snails make good use of their sneezes. They exude their mucus and let it spread out in the water above. Once a sufficient amount of tiny plankton has stuck to it, they eat it aaaaaaaall up!
As we all know, there's something deeply alluring about a massive web of mucus spewing forth from one's mouth and wafting delicately in the breeze. So it's inevitable that the mucus net would be used in reproduction.
Worm Snails are not hermaphrodite (it bears noting), so the female uses her net to catch the sperm packets released by the male. Her eggs are thereby fertilised, and eventually a whole bunch of tiny Worm Snails are released into the world. They look quite normal at first as they crawl around looking for a nice place to spend the rest of their lives. Only then will they cement themselves to the sea floor and grow their increasingly bizarre shell.
|Image: Ryan Somma|
Some youngsters don't go far, and giant colonies develop
Just a bit of glitz and glamour to remind Worm Snails where they come from!