Lepidochitona cinerea
MOLLUSCA
Polyplacophora
🐚🛸 This is a 𝗰𝗵𝗶𝘁𝗼𝗻! They are shelled mollusks like limpets but don’t you think that they look like spaceships or a robots with their very peculiar shell made of 8 plates?
🪨🕶️ They are very commonly found under rocks of the intertidal zone, and this one just wishes to go hide again… These creatures are sensible to dessiccation so they are avoiding light and looking for the shade. This behavior is called photophobia. This is exactly what we can see here, he is moving away form the strong light of my binocular!
👀🤖 But if they can avoid light, how can they sense it? there is no visible eyes! Actually, what looks like a basic shell is a structure full of sensors (is it me or it is getting more and more similar to a spaceship?!) Chiton have light sensitive structures in their shell plates called 𝗮𝗲𝘀𝘁𝗵𝗲𝘁𝗲𝘀, and some species even have mineral based lenses embedded in the shell!
🛸🫀 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.
Sources

- WoRMS
- Doris
- https://eartharchives.org/articles/chitons-can-see-you/index.html
- https://www.sciencedaily.com/releases/2024/03/240304135801.htm
- https://www.science.org/doi/10.1126/science.adg2689
- https://ucmp.berkeley.edu/taxa/inverts/mollusca/polyplacophora.php
- Baxter JM, Jones AM. Valve structure and growth in the chiton Lepidochitona cinereus (Polyplacophora: Ischnochitonidae). Journal of the Marine Biological Association of the United Kingdom. 1981;61(1):65-78. doi:10.1017/S0025315400045914
- Li L, Connors MJ, Kolle M, et al. Multifunctionality of chiton biomineralized armor with an integrated visual system. Science. 2015;350(6263):952-956. doi:10.1126/science.aad1246
- Sumner‐Rooney L, Sigwart JD. Do chitons have a brain? New evidence for diversity and complexity in the polyplacophoran central nervous system. Journal of Morphology. 2018;279(7):936-949. doi:10.1002/jmor.20823
- Speiser DI, Eernisse DJ, Johnsen S. A Chiton Uses Aragonite Lenses to Form Images. Current Biology. 2011;21(8):665-670. doi:10.1016/j.cub.2011.03.033