Carry On, My Gumboot Chiton
The gumboot chiton, also known as the giant Western fiery chiton, or the giant Pacific chiton (Cryptochiton stelleri) is a species of chiton native to the coasts of the Pacific ocean, particularly in North America from central California to the Aleutian Islands and along the coasts of Japan and the Korean peninsula. They reside primarily in rocky inter tidal zones and shallow bays with high amounts of algae and seaweed. Although they are exclusively aquatic, gumboot chitons are able to withstand exposure to the air for up to several hours, provided their gills remain wet.
Gumboot chitons hold the record as the largest species of chiton; adults can regularly grow up to 36 cm (14 in) long and weigh up to 2 kg (4.4 lb). As a mollusk, their bodies are comprised of a large muscle called a 'foot' which is used both for mobility and for sealing itself to rocks to prevent being knocked around by incoming waves; eight armored plates called valves than run down its back, and a thick leathery skin that helps to seal in moisture. The skin is usually red, pink, or purple, while the foot underneath is usually orange or yellow.
C. stelleri lead very slow, sedentary lives; an individual may travel less than 20 m (65 ft) in a single year. They are active mainly at night, and hide under rocks or in crevices during the day. Like many mollusks, they have small mouths with a set of specialized teeth which are used to scrape algae and seaweed off rocks. They may also filter small invertebrates and plankton from the water when available. Thanks to their armor, adult giant Pacific chitons have few natural predators. Their primary threat is the lurid rocksnail, a smaller mollusk which feeds on the gumboot chiton's leathery skin.
Spawning for gumboot chitons occurs in the summer; it can start as early as March and continue as late as July depending on local weather patterns. Females lay eggs in strings, which are quickly carried away by the waves and currents. When they detect a female has begun to release her eggs, nearby males will release sperm, which combine with the free-floating eggs. The fertilized eggs develop into larvae, which float for about 20 hours before settling. During this time, they are predated upon heavily by filter feeders, sea stars, urchins, and small fish. Though few survive to adulthood, those that do can live for over 40 years in the wild.
Human importance: Gumboot chitons are used as food and fish bait by many Native American, First Nations, and indigenous Korean and Japanese groups.
Conservation status: Giant Pacific chitons have not been evaluated by the IUCN. They are fairly common throughout their range, although population declines have been reported, likely due to disease and pollution.
Photos
Steven Calcote
Stephan Grace
Peter Pearsall
