Nudibranchs ( meaning naked – gill and pronounced NUDI BRANKS) are Sea slugs belonging to the class Gastropoda and are always a popular creature for divers to look out for.
They have soft bodies and in many cases are extremely colourful ranging in size from microscopic to almost two feet long !
They can be found in all our oceans throughout the world at all depths with many remaining undescribed. For more information about the biology of Nudibranchs please visit our Marine Biology Sea Slug page.
When pointing out Nudi’s during training dives for novices one of the most frequently asked questions is what do they eat ?? Sea slugs consume a wide variety of foods from Brozoans, Hydroids, Alge and even each other !!
The most common slugs encountered by divers are from the family Chromodoris they are mainly sponge feeders and represent some of the most colorful of all the families.
On a recent dive we captured some interesting,
descriptive shots of H. kanga feeding on its favored sponge food, image above and right.
We thought this post might interest marine enthusiasts and help them better understand the way Nudi’s eat.
As you can see in the first image, the mouth opening extends and it is literally hoovering up the living tissue of the sponge leaving only the white skeleton behind.
These animals use “chemical warfare” as means of defence. Storing toxins from the consumed food within their soft bodies. The toxins are either distasteful or poisonous to their predators. This form of protection has been so successful that many have evolved without a shell, unlike their land cousin the common snail.
Knowing the food source can help identify a species as coloration is often variable.
We have compiled a photographic Sea Slug Field Guide to assist divers in identifying their Nudibranch find, it is presented like a free book for all to use.