🛸🫀 Even if you don’t see it at the first glance, chiton have a well defined anatomy underneath the shell plates. There is a circulatory system with a heart, a digestive system, a nervous system, a reproductive system… The “head” is under the cephalic plate, that can be distinguished with its typical V-shape (left side of the 3rd panel).

👅🦷 On the anterior side, you can find the mouth and the radula, a special “teethed tongue” that chitons use to scrape calcareous algae of the rocks. Chitons also have a brain-like structure, in the form of a nerve ring located around the mouth.

🦶🪨 Just like other mollusks, they have a strong muscular foot to help them firmly attach to the substrate. It’s the equivalent of a very strong sucker! Try to remove a chiton from its rock, you will see!

🐚🧥 Did you know that mollusks shells are formed, repaired and maintained by a part of the anatomy called the mantle. In the case of our chiton, it’s called the mantle girdle.

👁️👁️The 2 small eye spots are not very developed and probably provide a quite basic vision. On the contrary, rhinophores – the two rolled antenna at the front of the head – are the main sensory organs of sea slugs.

👃💧Coming from the greek [rhino-] = nose, rhinophores can sense chemicals diluted in the sea water, like an aquatic sense of smell. They likely help the animals to locate food sources, predators, and partners of the same species.

⚧️🌀 Indeed, even if this sacoglossan species is a simultaneous hermaphrodite, the animals need to find a partner and act both as a male and female during cross-fertilisation. When they are done, the eggs are laid in a nice spirale on an algae, I hope to find one soon to show you!

🔰🫀 The two fleshy protrusionson each side of the body are called parapodia. On the inner side, we can see a network of dorsal vessels distributing the hemolymph – the equivalent of blood – from the heart to the entire body. This little guy has kept his parapods closed the whole time, but they sometimes extend to maximize the surface area, catch the sun’s rays and photosynthesize!

🔪🤕 Fun fact, a closely related species of sacoglossan (E.marginata) can perform an extreme form of autotomy. They can shed their entire body from the neck if they are attacked! The head is then sufficient to initiate a whole body regeneration and completely restore a functional body in no more than 18 days! Authors proposed that this amazing ability is facilitated by the endosymbiodic chloroplasts that provides energy independantly of food ingestion… I really wonder if Elysia viridis have the same surviving skills 🤔