Oregonia bifurca

Last updated

Contents

Oregonia bifurca
Oregonia bifurca male dorsal.jpg
Male
Oregonia bifurca female dorsal.jpg
Female
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Family: Oregoniidae
Genus: Oregonia
Species:
O. bifurca
Binomial name
Oregonia bifurca
Rathbun, 1902

Oregonia bifurca, commonly known as the split-nose crab or the split-nose decorator crab, is a species of crabs belonging to the family Oregoniidae. It is a rare deep-water species that inhabits the tops of seamounts and guyots in the northeastern Pacific Ocean; from the Aleutian Islands, the Bering Sea, the Hawaiian–Emperor seamount chain, to the waters off British Columbia. It is closely related to the more common shallow-water species Oregonia gracilis , the graceful decorator crab.

Like other majoid crabs, Oregonia bifurca are sexually dimorphic, with males larger than the females. The carapace length is about 33.7 millimetres (1.33 in) in males and 29 mm (1.1 in) in females. The entire body and the long and slender legs are covered densely with curving yellow hair.

Taxonomy

Oregonia bifurca is one of the two extant species classified under the genus Oregonia , the other being the graceful decorator crab ( Oregonia gracilis ). It belongs to the family Oregoniidae under the superfamily Majoidea ("spider crabs"). [1] It was first described by the American carcinologist Mary J. Rathbun in 1902. The single type specimen (a female) was collected from a depth of about 500 metres (1,600 ft) in the waters north of the Rat Islands of the Aleutian island chain (USS Albatross station 3785). [2]

Description

Oregonia bifurca are relatively small crabs. Like other members of Majoidea, they are sexually dimorphic. [3] Adult males grow to an approximate carapace length of 33.7 millimetres (1.33 in) with a carapace width of about 25 mm (0.98 in). [4] Adult females grow to an approximate carapace length of 29 mm (1.1 in) with a carapace width of about 20 mm (0.79 in). [3] [5]

Abdomen of male Oregonia bifurca male abdomen.jpg
Abdomen of male

The carapace is somewhat oblong in shape, about three-fourths as wide as it is long. It is slightly narrower at the anterior end. Two small spines are present at the posterior margin of eye orbit (the postorbital spines). The basal segments of the antennae are narrow and have small and stout forward-pointing spines, with smaller spines on the outer and inner margins. The rostrum is divided into two short, flat, and gradually tapering horns, hence the common name "split-nose". They measure about 5 mm (0.20 in) long in males and 3.4 mm (0.13 in) long in females, and are similar in shape to the postorbital spines. The upper and lower surfaces of the body covered densely with small protuberances (tubercles) with soft and long yellow hairs that curve at the tip. [4] [5] The abdomen (pleon) is composed of seven distinct segments. [3]

The appendages of males are slender and covered with dense long yellow curving hairs interspersed with shorter and finer hairs. The claw-bearing legs (chelipeds, the first pereiopod pair) are much longer and somewhat elongated in males than they are in females. Male chelipeds grow to a length of about 62 mm (2.4 in) with the claws (chelae) making up 25.6 mm (1.01 in). The arm (merus) of the chelipeds has two rows of spines on the inner margins, longer on the lower margin than on the upper margin. On the inner edge of the palm (manus) are four lengthwise rows of small spinules. The fixed finger (pollex) of the claw possesses a large tooth that fits into a groove in the movable finger (dactylus). They have a slight gape when closed fully, about two-fifths of the length from the base. They are about the same length as the palm. The walking legs (the rest of the pereiopods) gradually become shorter relative to each other from front-to-back, with lengths of approximately 59 mm (2.3 in), 56 mm (2.2 in), 51 mm (2.0 in), and 46 mm (1.8 in) respectively. The chelipeds in males are usually slightly longer than the first pair of walking legs. The first pair of pleopods of the males are also enlarged at the tips and possess rows of long filaments. [3] [4]

The appendages of females are also covered in dense long yellow curving hairs interspersed with shorter and finer hairs. Female chelipeds are much shorter than in males, only growing to about 37 mm (1.5 in). They are about one and a half times as long as the carapace. The arm of the chelipeds has a row of short blunt spines on the inner edge. The palm of the claws are about the same length as the fingers, and is slightly longer than the arm. The fixed finger and the moveable finger fit closely together and possess small teeth. Unlike in males, the cheliped is shorter than the first walking leg which is about 50 mm (2.0 in) in length. The rest of the walking legs also decrease in length front-to-back, as in males. [3]

Oregonia bifurca can be readily distinguished from O. gracilis in having shorter rostral horns that curve away from each other, triangular postorbital spines closer to the eyes and pointing more forward, a wider front end of the carapace, and long and slender dactyli on their walking legs. [3] The tuberculation in O. bifurca is finer than in O. gracilis. [4]

Distribution and habitat

Oregonia bifurca is a deep-water species usually found at depths of 500 to 1,400 m (1,600 to 4,600 ft). They live at the surface of seamounts and guyots, in habitats of sand, broken shell, and foraminiferous mud. Their habitat is mutually exclusive with that of O. gracilis, which is found in shallow water to only about 400 m (1,300 ft). [3] [6]

O. bifurca is a rare species. Aside from the waters around the Aleutian Islands, it has also been documented in the Bowers Bank of the western Bering Sea, [7] the Nintoku Seamount of the central Pacific Hawaiian–Emperor seamount chain, [6] and off the coast of British Columbia in North America. [8] [9]

Related Research Articles

<span class="mw-page-title-main">Japanese spider crab</span> Species of crab

The Japanese spider crab is a species of marine crab and is the biggest one that lives in the waters around Japan. It has the largest known leg-span of any arthropod around 3.7 meters. The Japanese name for this species is taka-ashi-gani,, literally translating to “tall legs crab”. It goes through three main larval stages along with a prezoeal stage to grow to its great size.

<span class="mw-page-title-main">Decapod anatomy</span> Entire structure of a decapod crustacean

The decapod is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various groups these may be reduced or missing. They are, from head to tail:

<i>Ocypode</i> Genus of tropical and subtropical crustaceans

Ocypode is a genus of ghost crabs found in the sandy shores of tropical and subtropical regions throughout the world. They have a box-like body, thick and elongated eyestalks, and one claw is larger than the other in both males and females. They inhabit deep burrows in the intertidal zone. They are primarily nocturnal, and are generalist scavengers and predators of small animals. The genus contains 21 species.

<i>Hemigrapsus crenulatus</i> Species of crab

Hemigrapsus crenulatus, the hairy-handed crab or papaka huruhuru, is a marine crab of the family Varunidae, endemic to the New Zealand coast, although a taxon in Chile may be conspecific. It is an intertidal species with semi-terrestrial tendencies. They are named by their characteristic setae, or patches of thick hair, on the chelipeds and legs. They can range from green to brown in coloration. Adult crabs are generally 2–4 cm (0.8–1.6 in) wide at the carapace, although the smallest mature crabs can be around just 1 cm (0.4 in) wide. and are able to survive and reproduce in environments of widely varying salinities.

<i>Notomithrax ursus</i> Species of crab

Notomithrax ursus, known as the hairy seaweed crab, is a spider crab of the family Majidae.

<i>Cherax parvus</i> Species of crayfish

Cherax parvus is a species of crayfish in the family Parastacidae. It is only known from its type locality – the Upper Tully River catchment in the Cardwell Range of north-eastern Queensland – and is listed as data deficient on the IUCN Red List. It was discovered in a rainforest catchment in a highland of northeastern Queensland during a Queensland Museum expedition to the upper Tully River area in November 1992. It is one of the smallest species in the genus. No species of Cherax has been considered endemic to wet upland or highland areas before it was discovered; most previous records were from elevations less than 400 meters. It also has several morphological features unique to the genus, and does not appear closely related to any extant species, suggesting a long period of geographic isolation.

<i>Guinotellus</i> Genus of crabs

Guinotellus melvillensis is a species of crabs in the family Xanthidae, the only species in the genus Guinotellus. It is a benthic crab with an ovate carapace within the subfamily Euxanthinae.

<i>Oregonia gracilis</i> Species of crab

Oregonia gracilis, commonly known as the graceful decorator crab, is a species of crab belonging to the family Oregoniidae. Like other decorator crabs it habitually attaches other organisms to its back. The sessile organisms are attached to hooked setae that act as a sort of velcro attachment. This decoration provides visual and chemical camouflage thus reducing predation risk. Pacific halibut are a major predator of O. gracilis. Other predators include octopus and sea otters. The main food source of O. gracilis is floating kelp and algae that they capture utilizing a waiting strategy in order to maintain cryptosis.

<i>Pugettia gracilis</i> Species of crab

Pugettia gracilis, commonly known as the graceful kelp crab, is a species of small crab in the family Epialtidae. It lives among forests of kelp on the Pacific coast of North America.

<i>Oregonia</i> (crab) Genus of crabs

Oregonia is a genus of crabs, comprising two extant species and one fossil species: It is classified in the family Oregoniidae under the spider crab superfamily Majoidea.

<i>Lybia tessellata</i> Species of crab

Lybia tessellata is a species of small crab in the family Xanthidae. It is found in shallow parts of the tropical Indo-Pacific Ocean. Like other members of the genus Lybia, it is commonly known as the pom-pom crab,cheerleader crab, or boxer crab because of its habit of carrying a sea anemone around in each of its claws, these resembling pom-poms or boxing gloves.

<i>Loxorhynchus grandis</i> Species of crab

Loxorhynchus grandis, commonly known as the sheep crab or spider crab, is a species of crab in the family Epialtidae. It is the largest crab found on the California coast. The species was first described to science by William Stimpson in 1857. The type specimen was collected on the coast of California, near San Francisco. Fossils from the late Miocene epoch indicate that this species is at least 11.63 to 5.333 million years old.

<i>Chaceon crosnieri</i> Species of crab

Chaceon crosnieri is a species of crab.

Chaceon bicolor is a species of crab. Chaceon bicolor differs from all species of the genus in color pattern, with the anterior part of the body purplish rather than reddish. In addition to color pattern, C. bicolor also differs from C. granulatus in having compressed rather than depressed dactyli on the walking legs; also, the hepatic region of the carapace in C. granulatus is coarsely granular, whereas it is smooth in C. bicolor. Juvenile specimens differ from adults in many features: the teeth of the carapace are much larger and sharper, there is a sharp spine on the carpus of the cheliped and a distal spine on the merus of each walking leg, plus the legs are longer and slenderer. Adult females differ from males in having much sharper anterolateral teeth on the carapace, sharper suborbital spines, and much shorter legs, with less trace of a distal dorsal projection on the merus. The carapace of females is more strongly arched from front to back and the protogastric regions are noticeably more inflated. The species is named as such because of its colour patter, purple an tan.

<span class="mw-page-title-main">Gulf ghost crab</span> Species of crab

The gulf ghost crab, Hoplocypode occidentalis, is a species of ghost crabs native to the Pacific coast of the Americas, from the Gulf of California to Colombia. It is the only species in the genus Hoplocypode. Gulf ghost crabs are medium-sized, reaching a maximum overall body diameter of 6 in (15 cm). They are one of only two ghost crab species found in the eastern Pacific. However, gulf ghost crabs can easily be distinguished from painted ghost crabs by the absence of "horns" on their eyes.

<i>Lauridromia</i> Genus of crabs

Lauridromia is a genus of crabs in the family Dromiidae. It contains only two species. At one time a third species, Lauridromia indica, was included in the genus but that has now been transferred to the genus Dromidiopsis as Dromidiopsis indica.

Lauridromia intermedia is a species of crab in the family Dromiidae and is native to the western Indo-Pacific. It often carries a piece of sponge on its back by way of camouflage, and one individual was found carrying a sea anemone in a similar manner.

Eurynome aspera, the strawberry crab, is a species of crab in the family Majidae.It is small (1–2 cm) and sometimes a vague strawberry colour. The carapace and legs are often encrusted with algae and mud which act as camouflage.

<i>Actaea savignii</i> Species of crab

Actea savignii is a species of Indo-Pacific crab from the family Xanthidae which is one of the spiny-legged rock crabs. It has colonised the Levantine Sea by Lessepsian migration through the Suez Canal from the Red Sea since the mid 2000s.

<i>Calcinus laevimanus</i> Species of crustacean

Calcinus laevimanus is a species of hermit crab in the genus Calcinus found in the Indo-West Pacific region, the type locality being Hawaii. It is also known as the blue-eyed hermit crab, zebra hermit crab, dwarf zebra hermit crab, left-handed hermit crab, Hawaiian reef hermit and other similar names.

References

  1. ↑ Davie, P. (2012). "Oregonia bifurca Rathbun, 1902". WoRMS. World Register of Marine Species . Retrieved September 7, 2012.
  2. ↑ Rathbun, Mary J. (1902). "Descriptions of new decapod crustaceans from the West Coast of North America". Proceedings of the United States National Museum. 24 (1272): 885–905. doi:10.5479/si.00963801.1272.885.
  3. 1 2 3 4 5 6 7 Garth, John S. (1958). Brachyura of the Pacific Coast of America, Oxyrhyncha (PDF). Allan Hancock Pacific Expeditions. Volume 21, Part 1. Los Angeles: The University of Southern California Press. pp. 135–141.
  4. 1 2 3 4 Rathbun, Mary J. (1925). The Spider Crabs of America (PDF). Bulletin (United States National Museum) 129. Washington: Government Printing Office. pp. 71–79.
  5. 1 2 Rathbun, Mary J.; Richardson, Harriet; Holmes, Samuel Jackson; Cole, Leon J. (1910). Harriman Alaska Expedition. Volume X: Crustacea. Harriman Alaska Series. Washington: Smithsonian Institution. pp.  171–172, pl. VI.
  6. 1 2 Sakai, Tsune (1978). Decapod Crustacea from the Emperor Seamount Chain (PDF). Researches on Crustacea, 8 (Suppl.). Tokyo: Carcinological Society of Japan. pp. 1–39.
  7. ↑ Takeda, Masatsune (1987). "Oregonia mutsuensis Yokoya, 1928, as a synonym of O. gracilis Dana, 1851" (PDF). Zoology, National Science Museum, Tokyo. 20: 133–136.
  8. ↑ Hart, Josephine F. L. (1980). "New records and extensions of range of reptant decapod Crustacea from the northeastern Pacific Ocean". Canadian Journal of Zoology. 58 (5): 767–769. doi:10.1139/z80-109.
  9. ↑ Boutillier, J. A. & Gillespie, G. E. (2005). "A phased approach to fishery development in the deep sea – a case study for the grooved tanner crab (Chionoectes tanneri)". In Shotton, Ross (ed.). Deep Sea 2003: Conference on the Governance and Management of Deep-sea Fisheries. Part 1: Conference reports. Rome: Food and Agriculture Organization of the United Nations. p. 240. ISBN   9789251054024.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.