Gumboot chiton
Encyclopedia
The gumboot chiton, Cryptochiton stelleri, also known as the giant pacific chiton, is the largest of the chiton
s, growing to 36 cm (14 in) and over 2000 grams. It is found along the shores of the northern Pacific Ocean
from Central California
to Alaska
, across the Aleutian Islands to the Kamchatka Peninsula
and south to Japan
. It inhabits the lower intertidal and subtidal zones of rocky coastlines.
Chitons are molluscs which have eight armored plates (called valves
) running in a flexible line down their back. Unlike most chitons, the gumboot's valves are completely hidden by its leathery upper skin or girdle
, which is usually reddish-brown, brown, and occasionally orange in color. The gumboot chiton's appearance has led some tidepoolers to fondly refer to it as the "wandering meatloaf."
or "gum rubber" boot. These boots were previously known as Gumboots. However, support for this apparent etymology
is scanty; the Giant Pacific Gumboot Chiton Homepage states "it has reminded others of the sole of a gum rubber boot", and an Alaskan seashore field guide says it is named "from the animal's resemblance to the rubber, or gum, boots worn by Alaska's coastal residents."
The Latin name Cryptochiton stelleri means Steller's hidden chiton. "Steller" is in honor of the 18th-century German zoologist Georg Wilhelm Steller
, who first described many species of the northern Pacific seashore. "Hidden" or "concealed" refers to the fact that the eight shelly plates characteristic of chitons are not visible, being totally internal in this genus of chiton. Many taxonomic names for chitons are based on the appearance of their plates or valves, and so it is most likely that the "hidden" portion of the name refers to the valves being completely obscured by the gumboot's girdle.
The gumboot chiton's underside is orange or yellow and consists mostly of a large foot similar to that of other molluscs like snails or slugs, with gill
s found in grooves running along the outer edge of the foot. The gumboot chiton is found clinging to rocks, moving slowly in search of its diet of algae
, scraped off of rocks with its rasp-like retractable radula
, covered with rows of magnetite
-tipped teeth. It also eats other marine vegetation such as sea lettuce
and giant kelp
. A nocturnal creature, the gumboot generally feeds at night and often remains in a hiding place during the day — although on foggy days it may be found exposed in tide pool
s or on rocks.
The gumboot can live for over 40 years. It has few natural predators, the most common being the lurid rocksnail, Ocenebra lurida — although the small snail's efforts to consume the chiton are generally limited to the outer mantle only. It is sometimes reported that the lurid rocksnail is in fact the gumboot chiton's only predator, but others list such animals as the sea star
Pisaster ochraceous, some octopus
species, and the Sea Otter
.
Several other animal species have been observed living within the gumboot's gills; the relationship is thought to be commensal
: neither harmful nor helpful to the chiton. One researcher found that more than a quarter of gumboots hosted an Arctonoe vittata, a pale yellow scale worm which can grow up to 10 cm in length. Opisthopus transversus, a small crab
, is also sometimes found within the gills.
Its flesh is edible, and has been used as a food source by Native Americans, as well as by Russian
settlers in Southeast Alaska
. However, it is not generally considered palatable, with a texture described as extremely tough and rubbery. The writers of Between Pacific Tides further detail the culinary drawbacks of the gumboot: "After one experiment the writers decided to reserve the animals for times of famine; one tough, paper-thin steak was all that could be obtained from a large cryptochiton, and it radiated such a penetrating fishy odor that it was discarded before it reached the frying pan."
The gumboot chiton's bony armoring plates, called "butterfly shells" due to their shape, can sometimes be found washed up on beaches, as can whole chitons: the gumboot keeps a weaker grip on the rocks that make up its home than most chitons do, and therefore it is not unusual for them to be knocked loose in heavy waves.
Chiton
Chitons are small to large, primitive marine molluscs in the class Polyplacophora.There are 900 to 1,000 extant species of chitons in the class, which was formerly known as Amphineura....
s, growing to 36 cm (14 in) and over 2000 grams. It is found along the shores of the northern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
from Central California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
to Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, across the Aleutian Islands to the Kamchatka Peninsula
Kamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...
and south to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. It inhabits the lower intertidal and subtidal zones of rocky coastlines.
Chitons are molluscs which have eight armored plates (called valves
Valve (chiton)
Valve is an anatomical term applied to the shell of molluscs. Although in theory any mollusc shell can be termed a "valve", the word is now most commonly applied to members of two classes of molluscs: the Bivalvia and the Polyplacophora , in other words, to those molluscs whose shells are normally...
) running in a flexible line down their back. Unlike most chitons, the gumboot's valves are completely hidden by its leathery upper skin or girdle
Valve (chiton)
Valve is an anatomical term applied to the shell of molluscs. Although in theory any mollusc shell can be termed a "valve", the word is now most commonly applied to members of two classes of molluscs: the Bivalvia and the Polyplacophora , in other words, to those molluscs whose shells are normally...
, which is usually reddish-brown, brown, and occasionally orange in color. The gumboot chiton's appearance has led some tidepoolers to fondly refer to it as the "wandering meatloaf."
Names
The name "Gumboot Chiton" seems to derive from a resemblance to part of a rubber Wellington bootWellington boot
The Wellington boot, also known as rubber-boots, wellies, wellingtons, topboots, billy-boots, gumboots, gummies, barnboots, wellieboots, muckboots, sheepboots, shitkickers, or rainboots are a type of boot based upon leather Hessian boots...
or "gum rubber" boot. These boots were previously known as Gumboots. However, support for this apparent etymology
Etymology
Etymology is the study of the history of words, their origins, and how their form and meaning have changed over time.For languages with a long written history, etymologists make use of texts in these languages and texts about the languages to gather knowledge about how words were used during...
is scanty; the Giant Pacific Gumboot Chiton Homepage states "it has reminded others of the sole of a gum rubber boot", and an Alaskan seashore field guide says it is named "from the animal's resemblance to the rubber, or gum, boots worn by Alaska's coastal residents."
The Latin name Cryptochiton stelleri means Steller's hidden chiton. "Steller" is in honor of the 18th-century German zoologist Georg Wilhelm Steller
Georg Wilhelm Steller
Georg Wilhelm Steller was a German botanist, zoologist, physician and explorer, who worked in Russia and is considered the discoverer of Alaska and a pioneer of Alaskan natural history.-Biography:...
, who first described many species of the northern Pacific seashore. "Hidden" or "concealed" refers to the fact that the eight shelly plates characteristic of chitons are not visible, being totally internal in this genus of chiton. Many taxonomic names for chitons are based on the appearance of their plates or valves, and so it is most likely that the "hidden" portion of the name refers to the valves being completely obscured by the gumboot's girdle.
Life
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s found in grooves running along the outer edge of the foot. The gumboot chiton is found clinging to rocks, moving slowly in search of its diet of algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, scraped off of rocks with its rasp-like retractable radula
Radula
The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...
, covered with rows of magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
-tipped teeth. It also eats other marine vegetation such as sea lettuce
Sea lettuce
The sea lettuces comprise the genus Ulva, a group of edible green algae that is widely distributed along the coasts of the world's oceans. The type species within the genus Ulva is Ulva lactuca Linnaeus, "lactuca" meaning lettuce...
and giant kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
. A nocturnal creature, the gumboot generally feeds at night and often remains in a hiding place during the day — although on foggy days it may be found exposed in tide pool
Tide pool
Tide pools are rocky pools by oceans that are filled with seawater. Many of these pools exist as separate entities only at low tide.Tide pools are habitats of uniquely adaptable animals that have engaged the special attention of naturalists and marine biologists, as well as philosophical...
s or on rocks.
The gumboot can live for over 40 years. It has few natural predators, the most common being the lurid rocksnail, Ocenebra lurida — although the small snail's efforts to consume the chiton are generally limited to the outer mantle only. It is sometimes reported that the lurid rocksnail is in fact the gumboot chiton's only predator, but others list such animals as the sea star
Sea star
Starfish or sea stars are echinoderms belonging to the class Asteroidea. The names "starfish" and "sea star" essentially refer to members of the class Asteroidea...
Pisaster ochraceous, some octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
species, and the Sea Otter
Sea Otter
The sea otter is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg , making them the heaviest members of the weasel family, but among the smallest marine mammals...
.
Several other animal species have been observed living within the gumboot's gills; the relationship is thought to be commensal
Commensalism
In ecology, commensalism is a class of relationship between two organisms where one organism benefits but the other is neutral...
: neither harmful nor helpful to the chiton. One researcher found that more than a quarter of gumboots hosted an Arctonoe vittata, a pale yellow scale worm which can grow up to 10 cm in length. Opisthopus transversus, a small crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
, is also sometimes found within the gills.
Human interaction
Russians
The Russian people are an East Slavic ethnic group native to Russia, speaking the Russian language and primarily living in Russia and neighboring countries....
settlers in Southeast Alaska
Alaska Panhandle
Southeast Alaska, sometimes referred to as the Alaska Panhandle, is the southeastern portion of the U.S. state of Alaska, which lies west of the northern half of the Canadian province of British Columbia. The majority of Southeast Alaska's area is part of the Tongass National Forest, the United...
. However, it is not generally considered palatable, with a texture described as extremely tough and rubbery. The writers of Between Pacific Tides further detail the culinary drawbacks of the gumboot: "After one experiment the writers decided to reserve the animals for times of famine; one tough, paper-thin steak was all that could be obtained from a large cryptochiton, and it radiated such a penetrating fishy odor that it was discarded before it reached the frying pan."
The gumboot chiton's bony armoring plates, called "butterfly shells" due to their shape, can sometimes be found washed up on beaches, as can whole chitons: the gumboot keeps a weaker grip on the rocks that make up its home than most chitons do, and therefore it is not unusual for them to be knocked loose in heavy waves.