Impurest's Guide to Animals #108 - Lined Chiton

As the charge through February continues we come to Issue 108 arriving in the wake of Valentine’s Day and all the emotional chaos left behind it. Last week we celebrated Chinese New Year with the endangered Golden Snub-nosed Monkey. This week we meet an armoured shore dweller with eyes of stone, clamped to the rocks of America’s West Coast. Hope you guys enjoy.


Issue #108 – Lined Chiton


Kingdom – Animalia

Phylum – Mollusca

Class – Polyplacophora

Order – Neoloricata

Family – Ischnochitonidae

Genus – Tonicella

Species – lineata

Related Species – The Lined Chiton is one of a number of Chitons or Coat-of-Mail Shells in the genus Tonicella (1)

Range – The Lined Chiton is found on the west coast of America ranging from California to Alaska, as well as the Aleutian Islands, Japan and the east coast of Russia.

In Armour Clad

The Lined Chiton is a medium sized shell, with a maximum length of 5cm. The shell of the chiton is formed of eight overlapping plates called valves, which possess colourful lines across the surface against a dull background. The valves are connected to the mantle known as a girdle, which is hairless and possesses a regular pattern of yellow blotches around the edge. The eyes of the chiton are embedded between the valves of the shell, and are formed of a crystal known as Argonite (CaCO3), which are known as Aesthetes (2). While largely immobile, the Lined Chiton is capable of moving on a single large foot concealed under the dorsal armour.


Lined Chitons are herbivores, and graze on red algae at night and at high tide using its radula which are hardened with microscopic iron and manganese teeth. Chitons generally shelter away from their feeding areas, and navigates using chemical cues in the rocks and sediment, and it is speculated that the species is able to remember topographic cues from its environment (3). The few predators who feed on Lined Chitons can only do so by exposing the unarmoured belly. When exposed chitons curl into balls, protecting their soft underside with the hardened dorsal valves and girdle.

Like all Chitons, the Lined Chiton is largely sedentary and reproduction is done at a distance, with male and females releasing sperm and eggs into the water. On fertilisation the eggs drift in the current before hatching, with the larvae floating in the current before growing small fragile valves on one side of the body before falling to the seabed as an immature adult.

Five Fun Lined Chiton Facts

The name Chiton comes from the Greek word ‘khiton’ which referred to a tunic that could be overlaid with armour and other clothing

Chitons can live up to 25 years

Upon death the valves on a Chitons body detach and are sometimes wash to shore where they are known as ‘Butterfly Shells’ due to their wing like appearance

While many other animals have more impressive dentition, the teeth of the Chiton (Chaetopleura apiculata) are the toughest in the animal kingdom.

While most Chitons have external armour, the Gumboot Chiton (Cryptochiton stelleri) is so large that the girdle has grown over the armoured valves on its back.



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2 - Li, Ling; Connors, Matthew; Kolle, Mathias; England, Grant; Speiser, Daniel; Xiao, Xianghui; Aizenberg, Joanna; Ortiz, Christine (20 November 2015). "Multifunctionality of chiton biomineralized armor with an integrated visual system". Science 350 (6263): 952

3 – Chelazzi, et al, 1983, 'A comparative study on the movement pattern of two sympatric tropical chitons, Mollusca: Polyplacophora', Marine Biology, vol 74, pp 115-125.; Chelazzi. G, et al, 1990, 'The role of trail following in the homing of intertidal chitons: a comparison between three Acanthopleura spp', Marine Biology, vol 105, pp 445-450

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Picture References

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Talk about being cold as stone, with metal teeth and crystal eyes the Lined Chiton is tough indeed. Next week we have the oldest extant animal species on Earth, one that has been hanging on for over 200 million years. But until then critic, comment and suggest future issues as well as making sure you check past issues in Impurest’s Bestiary.

Many Thanks

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