Black Leather Chiton

Capable of growing up to 12 cm, the animal is generally described as being football-shaped with a black leathery girdle in which are embedded eight protective plates. The parts of the plates that are visible are sometimes (but not always) diamond-shaped in outline. The underside of the animal is dull orange or yellow.

Its distribution ranges from Kamchatka, Russia through the Aleutian Islands to southern California. However, modern, accurate surveys do not exist.

Like other chitons, it is a slow moving grazer that consumes several species of brown and red algae including kelps, sea lettuce, and encrusting diatoms. They're also known to eat sponges, tiny barnacles, spirobid polychaetes, and bryozoans. Their predators include sea urchins, leather stars, black oystercatchers, glaucous-winged gulls, and humans.

Black Katy chitons are primarily dioecious, diploid organisms. They reach sexual maturity at about 35mm in length. The decrease in temperature experienced around fall will trigger within a newly settled organism the growth of the gonads. Around springtime, the increase in temperatures will trigger the actual production of gametes. Males will first disperse their sperm into the tides which will then induce nearby females to launch their eggs forth to be fertilized. Settlement of the organism is influenced by the presence of coralline algae. Gametogenesis takes place for 5 months of the year, and most of these chitons will live through the reproduction cycle about 3 times.

Black katy chitons are nutritious, being sources of Vitamin A, riboflavin, and niacin. As a common and nutritious species on rocky shores across the northwestern Pacific Coast, they are an important food source for people. The Indigenous peoples of California cook this animal on coals or in an earth oven. In the Pacific Northwest, black chitons are cooked -- typically quickly boiled -- or eaten raw. The Makah have historically used raw black chiton as a relaxant. Chitons are involved in Haida creation stories, as responsible for creating women, as well as in a story about a cooking contest between the Kitkatla people and the Skidegate Inlet people, where chitons are described as extremely quick to cook.