Sea slugs

Is it a worm? A snail? No, it’s a nudibranch!

Sea slugs (also known as “nudibranchs”) are amazingly beautiful creatures! There are more than 3000 different species of nudibranchs currently known. The word nudibranch comes from the Latin nudus (meaning naked) and the Greek brankhia (meaning gills) — this is because most of them breathe (take oxygen from the water) using tufts of “gills” — appendages that stick up into the water from their backs.

Where do they live?

They are found on seafloors all over the world, usually 10 metres or more below the surface. They constantly glide along, using their muscular foot, over sediment, seaweed, rocks, sponges corals and other substrates, often taking on the colours and patterns of those substrates, which make for a very effective camouflage.

Sometimes they will also swim from place to place, undulating through the water by flapping their body and cerata to and fro.

Poor vision

They can see light and dark, but not their own brilliant coloration. With their limited vision, their sense of the world is obtained through their rhinophores (on top of the head) and oral tentacles (near the mouth).

The body

Their body is soft and fleshy, they move around on a long muscular foot (similarly to land snails) and they have specialised tentacles (rhinophores) on their head that scientists believe they use to touch and sense their immediate environment.

Some nudibranchs have a bushy cluster of gills toward the back of their body that they use for respiration, while others have tentacle-like structures (cerata) all over their body that are used for both respiration and defence.

Published in Dawn, Young World, October 6th, 2018