Chelidonura livida from the Red Sea

Dear Oren,
Thanks for these photos of what, until very recently, has been an unknown species. I have included a close-up alongside to show some features of its head. Although difficult to see, species of Chelidonura has groups of sensory bristles along the front edge of the head which they use to 'smell' their prey, almost certainly by sensing chemicals in the mucus trail of their prey. Until recently we had no idea what Chelidonura ate, but we now know that at least some species feed on small flatworms. If you get the opportunity to see any species of Chelidonura feeding, or get the chance to put a small flatworm in front of a Chelidonura and watch what happens, it would be a valuable bit of information.

On each side of the central black bump on the front of the head is a small black spot. These are its eyes. However they can't form images, and as far as we know all they can possibly do is sense light and dark, so may be useful in letting the slug know when it is in a dark place [safe from predators] or for sensing a shadow [perhaps a predator] passing over it? One other possible use is to help 'set the time' on its biological clocks. We know in some land snails that the eyes have associated cells producing hormones involved in daily and more long-term rhythms so its possible that the same mechanisms apply in slugs.. Certainly aglajids and other bubble-shells I have kept in aquaria had well developed daily rhythms, burrowing into the sand and emerging from the sand with remarkable regularity each day.

Best wishes,
Bill Rudman