Thorny skate

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Thorny skate
Amblyraja radiata Gervais.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Rajiformes
Family: Rajidae
Genus: Amblyraja
Species:
A. radiata
Binomial name
Amblyraja radiata
(Donovan, 1808)
Synonyms
  • Raja radiata

The thorny skate (Amblyraja radiata) is a species of fish in the family Rajidae. This bottom-living skate lives in the North and south-eastern Atlantic Ocean in depths ranging from 20 to 1,000 m (66–3,281 ft) and water temperatures from −1 to 14 °C (30–57 °F). [1]

Fish vertebrate animal that lives in water and (typically) has gills

Fish are gill-bearing aquatic craniate animals that lack limbs with digits. They form a sister group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered paraphyletic by excluding the tetrapods. Because in this manner the term "fish" is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology, unless it is used in the cladistic sense, including tetrapods. The traditional term pisces is considered a typological, but not a phylogenetic classification.

Skate (fish) family of fishes

Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. More than 150 species have been described, in 17 genera. Softnose skates and pygmy skates were previously treated as subfamilies of Rajidae, but are now considered as distinct families. Alternatively, the name "skate" is used to refer to the entire order of Rajiformes.

Contents

Species description

Amblyraja radiata no.jpg

The thorny skate reaches up to 1.05 m (3.4 ft) in total length and 11.4 kg (25 lb) in weight. [1] Its underside is smooth, but the upper side, as the name suggests, is very rough with many small thorns all over and 13-17 larger ones in line from the back of the head to end of the tail. The top side is brown with possibly black spots and the underside is white. It has a hard, roughly triangular snout and a tail, which is shorter than its body. It eats crustaceans, small fishes, and worms. It produces egg capsules, which are 3.4-8.9 cm long and 2.3-6.8 cm wide, which hatch outside the body.

Egg case (Chondrichthyes) natural collagen casing found encompassing some aquatic lifeforms fertilized eggs

An egg case or egg capsule is the casing that surrounds the eggs of oviparous sharks, skates, and chimaeras. Egg cases typically contain one embryo, except for big skate and mottled skate egg cases, which contain up to 7 embryos. Oviparity is completely absent in the superorder Squalomorphii.

Conservation status

Thorny skate are taken as bycatch in some fisheries. It is a U.S. National Marine Fisheries Service species of concern, which are those species about which the U.S. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. Endangered Species Act.

National Marine Fisheries Service

The National Marine Fisheries Service (NMFS) is the United States federal agency responsible for the stewardship of national marine resources. The agency conserves and manages fisheries to promote sustainability and prevent lost economic potential associated with overfishing, declining species, and degraded habitats.

National Oceanic and Atmospheric Administration An American scientific agency within the US Department of Commerce that focuses on the oceans and the atmosphere

The National Oceanic and Atmospheric Administration is an American scientific agency within the United States Department of Commerce that focuses on the conditions of the oceans, major waterways, and the atmosphere.

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<i>Raja</i> (genus) genus of fishes

Raja is a genus of skates in the family Rajidae containing 16 species. Formerly a wastebasket genus, many species historically placed here have been moved to other genera in the family, such as Amblyraja, Beringraja, Dipturus, Leucoraja and Rostroraja. Raja are flat-bodied, cartilaginous fish with a rhombic shapes due to their large pectoral fins extending from or nearly from the snouts to the bases of their tails. Their sharp snouts are produced by a cranial projection of rostral cartilage. The mouth and gills are located on underside of the body. They may be either solid-coloured or patterned, and most skates have spiny or thorn-like structures on the upper surface, and some species contain weak electrical organs within their tails. Mating typically occurs in the spring and the female lays numerous eggs per clutch which are encapsulated in leathery cases, commonly known as "mermaid’s purses". Species vary in size, ranging from about 40 to 140 cm (1.3–4.6 ft) in length. These bottom-dwellers are active during both day and night, and typically feed on molluscs, crustaceans and fish. Raja skates are found in the East Atlantic, including the Mediterranean, and western Indian Ocean, ranging from relatively shallow water to a depth of 800 m (2,600 ft). Skates and related species have fossil records dating from the Upper Cretaceous period, thus this well adapted species is quite ancient.

Barndoor skate species of fish

The barndoor skate is a species of marine cartilaginous fish in the skate family Rajidae of the order Rajiformes. It is native to the northwestern Atlantic Ocean, and is found from the Grand Banks of Newfoundland and the southern side of the Gulf of St. Lawrence south to North Carolina. The fish is one of the largest skates found in the North Atlantic Ocean, reaching lengths up to 1.5 m (5 ft). It is carnivorous, feeding on invertebrates and other fish found near the sea floor.

Thornback ray species of fish

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The bottlenose skate, spearnose skate, or white skate is a species of skate in the family Rajidae. It is a benthic fish native to the coastal eastern Atlantic Ocean. Due to overfishing, it has been depleted or extirpated in many parts of its former range in the northeastern Atlantic and the Mediterranean Sea, and is now endangered.

Broad skate species of fish

The broad skate is a poorly known species of skate in the family Rajidae. It occurs at depths of 846 to 2,324 metres, and has been observed via remotely operated underwater vehicle by the Monterey Bay Aquarium Research Institute as deep as 3,167 metres (10,390 ft), making it one of the deepest-occurring skates known. It is sporadically distributed in the Pacific Ocean, from the Gulf of Panama to British Columbia and the Bering Sea, to the Tohoku Slope off northern Honshu and the Okhotsk Slope off Hokkaido. The species name, badia, comes from the Latin batius meaning "brown", referring to its color.

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Undulate ray species of fish

The undulate ray is a species of ray and cartilaginous fish found in the Mediterranean and East Atlantic from southern Ireland and England to the Gulf of Guinea. It is found in areas with mud or sand, and may occur as deep as 200 m (660 ft), though it prefers shallower depths. It is considered endangered due to overfishing.

The bigmouth skate is a species of fish in the family Rajidae. It lives near the bottom in deep waters in Southeast Atlantic in depths below 1000 m. Its maximum size is 77 cm. It has a hard, roughly triangular snout and smooth body with star-based thorns around its eyes, tail, and elsewhere. Its top side is dark gray and underside has white spots. As the name suggests, it has a large mouth.

Arctic skate species of fish

The Arctic skate is a species of fish in the family Rajidae. It lives near the seabed between 140 and 2,500 m deep in the Arctic Ocean and waters around Canada and northern and north-western Europe, in the northern Pacific Ocean, and in waters surrounding Antarctica and New Zealand.

Jensen's skate, also known as the shortail skate, is a poorly known species of fish discovered in 2004 during a study of bottom ichthyofauna aboard the Norwegian RV G.O. Sars, where four species were identified, including A. jensieni.

Eudactylina corrugata is a species of parasitic copepod found on the little skate and the thorny skate that is only known from St. Andrews, New Brunswick and Woods Hole, Massachusetts.

References

  1. 1 2 Froese, Rainer and Pauly, Daniel, eds. (2017). "Amblyraja radiata" in FishBase . December 2017 version.