Skate

Taxobox
name = Skates


image_width = 220px
image_caption = Barndoor Skate, "Dipturus laevis"
regnum = Animalia
phylum = Chordata
classis = Chondrichthyes
subclassis = Elasmobranchii
superordo = Batoidea
ordo = Rajiformes
familia = Rajidae
subdivision_ranks = General
subdivision =

Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. They are carnivorous, feeding mostly on smaller fish and crustaceans. They have flat pectoral fins continuous with their head, two dorsal fins and a short, spineless tail. There are more than 200 described species in 25 genera.

Skates are bottom-dwelling and are found throughout the world from continental shelves down to the abyssal zone. They are oviparous fishes, laying eggs in a case known as a mermaid's purse. It is thought that egg-laying in skates is an evolutionary reversal, that is, skates are descended from ovoviviparous ancestors. [FishBase family | family = Rajidae | month = August | year = 2005]

The common skate, "Dipturus batis", is the largest found in British waters. It has a long, pointed snout. However, the most common skate in British seas is the thornback ray, "Raja clavata". They are frequently caught by trawling. Common skate and white skate are assessed as Critically Endangered by IUCN (World Conservation Union) and the fish is listed by the Marine Conservation Society as a "fish to avoid". [ [http://www.fishonline.org/advice/avoid/?item=35 "Fish to Avoid: Skate"] from the Marine Conservation Society, retrieved November 11, 2006]

The big skate, "Raja binoculata", and longnose skate, "Raja rhina", are among the most common found in the Pacific Ocean, ranging from southern Alaska to northern Mexico. The big skate , also known as the Pacific great skate, reaches a width of 2.4m (8 ft.) across.

Genera

* "Amblyraja"
* "Arhynchobatis"
* "Atlantoraja"
* "Bathyraja"
* "Breviraja"
* "Cruriraja"
* "Dactylobatus"
* "Dipturus"
* "Fenestraja"
* "Gilotea"
* "Gurgesiella"
* "Irolita"
* "Leucoraja"
* "Malacoraja"
* "Neoraja"
* "Notoraja"
* "Okamejei"
* "Pavoraja"
* "Psammobatis"
* "Pseudoraja"
* "Raja"
* "Rajella"
* "Rhinoraja"
* "Rioraja"
* "Rostroraja"
* "Sympterygia"
* "Zearaja"

Endangerment

Skates have slow growth rates and, since they mature late, low reproductive rates. As a result skates are vulnerable to overfishing and it appears that skates have been overfished and are suffering reduced population levels in many parts of the world. The barndoor skate, "Raja laevis", is currently listed with the IUCN as vulnerable due to being severely overfished. [http://www.flmnh.ufl.edu/fish/gallery/descript/bigskate/bigskate.html Florida Museum of Natural History] However, population data is lacking to determine the exploitation of the big skate at this time.

See also

* Anacanthobatidae, the family of smooth skates.
* Jenny Haniver, a fake sea monster created from a skate corpse

References

External links

* ARKive - [http://www.arkive.org/species/GES/fish/Dipturus_batis/ images and movies of the common skate "(Dipturus batis)"]
*Kliman, Todd. " [http://www.washingtonian.com/articles/bestbites/302.html Skate Goes From Trash Fish to Treasure] ", "Washingtonian", May 1 2006.