Scientific name: Â Tonicella lineata
Author: Â Bowie Connor
Length:  to 2″ (5cm)
Identification: The lined chiton is one of the prettiest chitons in the Pacific Northwest. It can be in many colours ranging from pink, red to orange and they often have vibrantly coloured lines zig-zagging along the valves (plates) – the one in our photo has electric blue zigzags. The mantle often has a light coloured pattern. There are many species that look similar to the lined chiton so it is best to have descriptions and photos of each for a positive identification.
Habitat: Lined chitons can be found from northern Japan, Southern Alaska and all the way down to the Channel Islands of California . Though they can be found up to 52m deep they are often found on rocky shores in the intertidal and subtidal zones. They are often found on rocks with pink coralline algae, one of the main algaes it likes to eat.
Natural History: Chitons have lived for up to 500 million years! They have 8 solid plates made of calcium carbonate, providing protection from above, but also flexible enough that they can roll into a ball when threatened. On the underside of their body, they have one large muscular foot surrounded by the mantle cavity. The foot moves along rocks helped by mucus secreted by the chiton. The mantle cavity contains gills (ctenidia) around the outside of the foot that help them breathe underwater, and also the gonopore, a reproductive pore. At the front of the foot they have a mouth that sucks up algae and nutrients as it moves along the substrate. Like most molluscs, the lined chiton has a unique radula that helps with processing food, almost like if our tongues were lined with rows of hundreds of sharp teeth! Chitons need to have super hard teeth to chew up the algae from hard rocks. Their radular teeth are made of a rare iron that is said to be one of the strongest materials in the world. After, food is broken down further in the stomach and then continues through the intestine and to the anus, which is on the opposite end of a chiton’s mouth.
Predators: Â A few types of sea stars, river otters, and even ducks will eat lined chitons.
Life cycle:Â Â In the spring, males will release their sperm into the water and the females will release eggs. After the eggs are fertilized, the zygote will develop into a planktonic trochophore larva which will mature into a planktonic stage that will settle onto the sea floor. If the larvae cannot find algae the development will stop, but if they do they will grow into juveniles by secreting the formula for their shells and continuing to eat the algae.
Photograph: D. Young
References
Clark, R. (n.d.). CHITONS. Biological Science | CSUF. Retrieved January 31, 2023, from http://biology.fullerton.edu/deernisse/pubs/Eernisse_07_chitons_Tidepools.pdf
Fletcher, G. (2001, March 15). Tonicella lineata: the lined chiton. Race Rocks. Retrieved January 31, 2023, from https://racerocks.ca/tonicella-lineata-the-lined-chiton/
Fulton, K., & Wickham, S. (n.d.). Lined chiton • Tonicella lineata. Biodiversity of the Central Coast. Retrieved January 31, 2023, from https://www.centralcoastbiodiversity.org/lined-chiton-bull-tonicella-lineata.html