Placetron
Encyclopedia
Placetron wosnessenskii, common name the scaled crab, is a species
of king crab
found in most waters off North America
's west coast. It is the only species
in the genus Placetron.
narrowing at the anterior end much like a trapezoid, similar shaped chelae, and coloration ranging from a clouded green to reddish sometimes with banding along the legs. The name of this decapod is derived from the scale like pattern that covers its legs and partially covers its carapace. It should be noted the odd structure of the chelae which are spoon-like in nature and are largely covered in setae.
to Puget Sound
. In most instances it is found at depths of up to 110 metres (360.9 ft), but may also inhabit shallow intertidal areas. Possible areas on habitation include rocky substrates either near drop offs or among boulders.
s as they have been witnessed feeding on the echinoderms. Few other prey
species have been observed but it can assumed that other food sources are similar to those of similar crab species. The crab themselves are prey to the sea otter
and presumably other large predators. Females and males differ in the structure of their abdomen. The female's abdomen is covered in plates where as the male's is covered in vestigial plates. These plates give the male a rubbery look and feel to their abdomens. Many have be observed to have a symbiotic
relationship with certain species of sea anemone
. This is why you will also find them inhabiting areas containing Metridium senile
and Metridium giganteum.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of king crab
King crab
King crabs, also called stone crabs, are a superfamily of crab-like decapod crustaceans chiefly found in cold seas. Because of their large size and the taste of their meat, many species are widely caught and sold as food, the most common being the red king crab, Paralithodes camtschaticus.King...
found in most waters off North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
's west coast. It is the only species
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
in the genus Placetron.
Description
Major characteristics include a soft leathery abdomen, a wide carapaceCarapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
narrowing at the anterior end much like a trapezoid, similar shaped chelae, and coloration ranging from a clouded green to reddish sometimes with banding along the legs. The name of this decapod is derived from the scale like pattern that covers its legs and partially covers its carapace. It should be noted the odd structure of the chelae which are spoon-like in nature and are largely covered in setae.
Range and habitat
The scaled crab is found in waters ranging from Pribilof IslandsPribilof Islands
The Pribilof Islands are a group of four volcanic islands off the coast of mainland Alaska, in the Bering Sea, about north of Unalaska and 200 miles southwest of Cape Newenham. The Siberia coast is roughly northwest...
to Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
. In most instances it is found at depths of up to 110 metres (360.9 ft), but may also inhabit shallow intertidal areas. Possible areas on habitation include rocky substrates either near drop offs or among boulders.
Biology
The carapace width has been measured in size from 40 to 80 mm (1.6 to 3.1 ). Being a lithode crab it has an asymmetrical body. Diet of the scaled crab is known to include brittle starBrittle star
Brittle stars or ophiuroids are echinoderms in the class Ophiuroidea closely related to starfish. They crawl across the seafloor using their flexible arms for locomotion. The ophiuroids generally have five long slender, whip-like arms which may reach up to in length on the largest specimens...
s as they have been witnessed feeding on the echinoderms. Few other prey
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
species have been observed but it can assumed that other food sources are similar to those of similar crab species. The crab themselves are prey to 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...
and presumably other large predators. Females and males differ in the structure of their abdomen. The female's abdomen is covered in plates where as the male's is covered in vestigial plates. These plates give the male a rubbery look and feel to their abdomens. Many have be observed to have a symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
relationship with certain species of sea anemone
Sea anemone
Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...
. This is why you will also find them inhabiting areas containing Metridium senile
Metridium senile
Metridium senile, common name the plumose anemone or frilled anemone, is a species of sea anemone in the family Metridiidae. It is found in the seas off northwest Europe and the east and west coasts of North America.-Description:...
and Metridium giganteum.