Food chain

Dear Lorna,
Snails and Sea Slugs are very closely related. The shell, which is often very strong, helps to protect snails from being eaten by other animals. Slugs however have had to find other ways to try and protect their soft bodies from attack. In case you don't have much experience with using the world wide web, perhaps I should say that if you click on any word in my message which is underlined, you will be taken to a page on that subject.

If you go to the page on Opisthobranch Defence you will find a list of pages which have information on different aspects of their defence. Many sea slugs have nasty tasting chemicals in their skin to protect them, and some have become brightly coloured to warn fish that they are very bad tasting. One group, the aeolids, take stinging cells from their sea anemone (and other cnidarian) prey and store these up to use in their own defence. Have a look at all the pages listed as they all have interesting stories to tell.

Now to you question about who or what eats sea slugs. It is very difficult to collect this sort of information because sea slugs don't leave much trace behind. They don't have a shell or bones, so a biologist studying the food of an animal by looking at the undigested remains in its stomach or its faeces will find no recognsiable traces of seas slugs except in rare cases. The only other way to find what eats them is to observe them being eaten in the field, and that is very difficult. I have listed the few records I know of other animals eating sea slugs at the top of this page.

One group in the list that eats sea slugs is the Genus Gymnodoris which are themselves nudibranch sea slugs, specialised in eating other sea slugs. If you look at the relevant Gymnodoris pages you will see some great photos of them feeding.

Best wishes,
Bill Rudman.