Yeti Crab ( Kiwa hirsuta )
The Yeti Crab ( Kiwa hirsuta, English yeti crab ) is one of two types of cancer in the family Kiwaidae. She lives on the hydrothermal fields of the deep sea in about 2200 meters depth. These fields are characterized by vents, called black smokers. To their trivial names they came because of their completely white appearance and bristles on the limbs. The eponym was about the mythical creature Yeti.
- 6.1 Notes and references
- 6.2 Literature
- 6.3 External links
Size and color
The carapace of the Yeti crab was 5.86 inches long when holotype 5.15 inches, together with the rostrum. Including Chelipeden (scissors ) measures the animal stretched about 15 centimeters. The carapace is about one- third longer than wide. The Yeti crab is up on yellow spines completely white at the extremities of the Chelipeden.
The dorsal surface of the carapace is smooth; Width and length of the telson ( the rearmost body segment ) match approximately. The Telson is divided by a transverse seam at a front and rear part.
The front lip is characterized by a slight angle and small teeth near the rostrum. The broad and triangular rostrum is dorsally ( back down) slightly concave. Furthermore, it is provided on the side and rough with long bristles and ventral ( lower or bauchwärtige ) page is bowl -shaped. A sloping, located in the middle suture ( suture ) separates the anterior from the posterior part of the body of the Yeti crab. The approach of the fifth pereiopods is not visible, it is below the plastron (sign of the " abdomen ", ventrally located ) to find.
With the life in the completely lightless deep-sea was accompanied by a reduction of the eyes: You are in the Yeti crab only as membranous rudiment without pigments available, resulting blindness results. Therefore, the Yeti crab must rely on their antennae and other senses; the bristles may play a role in perception as sensors of water eddies and others. The antennas are missing scales.
Both walking legs and Chelipeden are covered by dense bristles and a number of rows of prongs. The spines of the Yeti crab are characterized by a granular, yellow drawing and a " tuft " of long, feathery and dense bristles. Towards the middle and ventral bristles are more dense than the side and move forward. The spines on the anterior parts of the Chelipeden missing this crested -like structure.
The Chelipeden are approximately symmetrical, triangular and slightly more than twice as long as the carapace with rostrum. You are not occupied by bristles. The located on the scissors spines become smaller the further they are removed from the body, and finally completely missing. The fingers are movable, and towards the body a sharp edge with smooth, flat, especially heavily horny scales to the middle followed by a perforated area.
The bristles are among the special features of Yeti crab, as they are present in very large numbers. The Peraeopoden and partly also the Chelipeden are littered with such bristles. The bristles are very flexible, about 15 millimeters long and busy especially in the distal, that is located away from the body area with filamentous bacteria. These bacteria are thought to be part of the diet. Some bristles are occupied on average only 13 millimeters long and not by bacteria but significantly harder, equipped with barbs and end in a thorn.
Way of life
Over the life of the Yeti crab, as with other deep-sea dwellers poorly understood yet. The animals come at a density of one to two animals per 10 square meters in the vicinity of active hydrothermal vents or on the basis of such vents before. They live together with shells of the genus Bathymodiolus, crustaceans of the genus Munidopsis, crabs of the genus Bythograea and marine gastropods of the family Buccinidae. The animals are probably related cancers, as well as omnivores; in the discovery of Yeti crabs were observed, which ate the meat of damaged by the collecting activities shells.
Up to now, the occurrence Yeti Crab from three hydrothermal fields are known. It is Sebastian 's Steamer (37 ° 47'48 " S, 110 ° 54'85 'W, depth 2204 meters), Pâle Étoile (37 ° 47'36 " S, 110 ° 54'85 W, depth 2215 meters ) and Annie's Anthill (37 ° 46'49 " S, 110 ° 54'72 'W, depth 2228 meters). All three fields are close together in the South Pacific, south of Easter Island. You may still deposits of other hydrothermal fields available. At the moment it is assumed that the Juan Fernandez plate, a small tectonic plate, geologically marks the northern limit of distribution of the Yeti crab.
Within the Crustacea, the Yeti Crab is in the group of medium crabs ( Anomura ); different than the misleading name suggests, does not belong to the animal group of crabs ( Brachyura ). Because of its many unique features of its own superfamilies have been prepared for the Yeti crab Kiwaoidea. Molecular- biological studies have led to significant differences in relation to other groups of crustaceans. This DNA was recovered from the muscles of the Yeti crab. We found distinct differences from other families of the Gala Theo Idea ( Spring and porcelain crabs ).
Obviously, the family is Kiwaidae families Chirostylidae, Galatheidae ( squat lobsters ) and Porcellanidae (porcelain crabs ) closer than the Aeglidae. The superficial similarities to Chirostylidae consist of common characteristics of the antennas and the third Maxillpeden, a transverse suture on telson and the sternum without a record of the last of the thorax Thus situated. Some similarities also exist with the Aeglidae, in the form of sternites between the third Maxillpeden, but separate in the Aeglidae calcified structures that look like optical lines, the carapace in different regions. These lines are not present in the Kiwaidae. Among the significant differences between the Chirostylidae and Kiwaidae include the missing antenna scales as well as the reduced eye for the Yeti crab, the larger sternite between the third maxillipeds with the family Kiwaidae, the non-visible approach of the fifth Peraeopoden, as well as several other features, inter alia, the presence of grooves on the surface of the carapace of Kiwa.
Following recent studies, the family of Kiwaidae was placed in the superfamily Chirostyloidea. After the discovery of a second Kiwa - type ( Kiwa puravida ) the species is no longer monotypic.
History of Research
The Yeti crab were by scientists Enrique Macpherson (Spain, Centro de Estudios Avanzados de Blanes ( CSIC) ), William Jones (USA, Monterey Bay Aquarium Research Institute ( MBARI ) ) and Michel Segonzac (France, Ifremer ) in 2005 as Kiwa hirsuta firstdescribed. The genus name Kiwa is also the name for the Polynesian goddess of crustaceans ( the yeti crab was about 1500 kilometers south of Easter Island discovered ), the artbezeichnende second part ( epithet ) of the scientific name, hirsuta, meaning " hairy ". The research vessel PAR 5 (Pacific - Antarctic Ridge 5) drove in the period from March to April in an event organized by MBARI expedition to the said hydrothermal fields. The cancer was collected with the deep-sea submersible Alvin. During the expedition only Michel Segonzac of Ifremer was present.
The trapped there holotype is now preserved in the Ifremer in Brest.
Discovered but not collected and described, however, the species was significantly earlier by the German research vessel sun SO -157 in 2001 .. Because of the peculiar appearance that recalls the basis of the bristles in a certain way to a Yeti, the cancer was so popular that in the first weeks replicas of the Yeti crab came on the market after the discovery in Japan.