Angel shark

Angel shark

Overview
The angel sharks are an unusual genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

s with flattened bodies and broad pectoral fins that give them a strong resemblance to rays
Batoidea
Batoidea is a superorder of cartilaginous fish commonly known as rays and skates, containing more than 500 described species in thirteen families...

. The more than 16 known species are in the genus Squatina, the only genus in its family, Squatinidae, and order Squatiniformes. They occur worldwide in temperate and tropical seas. Most species inhabit shallow temperate or tropical seas, but one species inhabits deeper water, down to 1300 metres (4,265.1 ft).

While the forward part of the angel shark's body is broad and flattened, the rear part retains a muscular appearance more typical of other sharks.
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Encyclopedia
The angel sharks are an unusual genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

s with flattened bodies and broad pectoral fins that give them a strong resemblance to rays
Batoidea
Batoidea is a superorder of cartilaginous fish commonly known as rays and skates, containing more than 500 described species in thirteen families...

. The more than 16 known species are in the genus Squatina, the only genus in its family, Squatinidae, and order Squatiniformes. They occur worldwide in temperate and tropical seas. Most species inhabit shallow temperate or tropical seas, but one species inhabits deeper water, down to 1300 metres (4,265.1 ft).

Appearance and biology


While the forward part of the angel shark's body is broad and flattened, the rear part retains a muscular appearance more typical of other sharks. The eyes and spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...

s are on top, and the five gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

 slits are underneath. Both the pectorals and the pelvic fins are large and held horizontally. There are two dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

s, no anal fin, and unusually for sharks, the lower lobe of the caudal fin is longer than the upper lobe. Most types grow to a length of 1.5 m (5 ft), with the Japanese angel shark
Japanese angel shark
The Japanese angelshark is a species of angel shark, family Squatinidae, found in the western Pacific from Japan, the Yellow Sea, Korea, northern China, and the Philippines between latitudes 41° N and 19° N...

, Squatina japonica, known to reach 2 m.
Angel sharks possess extensible jaws that can rapidly snap upwards to capture prey, and have long, needle-like teeth. They bury themselves in sand or mud lying in wait for prey, which includes fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, and various types of mollusks. They are ovoviviparous
Ovoviviparity
Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch...

, producing litters of up to 13 pups.

Behavior


Although this shark is a bottom dweller and appears harmless, it should be respected due to its powerful jaws and sharp teeth which can inflict painful lacerations if provoked. It may bite if a diver approaches the head or grabs the tail.
If they are left alone, they will not attack.

Commercial value


The sharks were long considered of no commercial interest, but in 1978, Michael Wagner, a fish processor in Santa Barbara, California
Santa Barbara, California
Santa Barbara is the county seat of Santa Barbara County, California, United States. Situated on an east-west trending section of coastline, the longest such section on the West Coast of the United States, the city lies between the steeply-rising Santa Ynez Mountains and the Pacific Ocean...

, began to promote angel sharks, and 310 metric tons were taken off California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 in 1984. The fishery devastated the population and is now regulated.

Angel sharks have historically been heavily fished but education has played a role in reducing overfishing
Overfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....

 of these slow-reproducing chondrichthyes. In April 2008 the UK Government afforded the angel shark full protection under the Wildlife and Countryside Act.

Species

  • Squatina aculeata Cuvier
    Georges Cuvier
    Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...

    , 1829
    (Sawback angelshark)
  • Squatina africana Regan, 1908 (African angelshark)
  • Squatina albipunctata Last & W. T. White, 2008 (Eastern angelshark)
  • Squatina argentina (Marini, 1930) (Argentine angelshark)
  • Squatina armata (Philippi {Krumweide}
    Rodolfo Amando Philippi
    Rodolfo Amando Philippi was a German-Chilean paleontologist and zoologist....

    , 1887)
    (Chilean angelshark)
  • Squatina australis Regan, 1906 (Australian angelshark)
  • Squatina caillieti
    Squatina caillieti
    Squatina caillieti is a species of angel shark, family Squatinidae, known only from a long immature female caught in the Philippines, where it is the only known representative of its family. It has a flattened body and head with greatly expanded pectoral and pelvic fins, and is greenish above with...

    Walsh, Ebert & Compagno, 2011
  • Squatina californica Ayres
    William Orville Ayres
    William Orville Ayres was an American physician and ichthyologist. Born in Connecticut, he studied to become a doctor at Yale University School of Medicine....

    , 1859
    (Pacific angelshark)
  • Squatina dumeril Lesueur
    Charles Alexandre Lesueur
    Charles Alexandre Lesueur was a French naturalist, artist and explorer.Pictured here is the oil portrait by Charles Willson Peale of Charles-Alexandre Lesueur...

    , 1818
    (Sand devil)
  • Squatina formosa S. C. Shen & W. H. Ting, 1972 (Taiwan angelshark)
  • Squatina guggenheim Marini, 1936 (Angular angel shark)
  • Squatina heteroptera Castro-Aguirre, Espinoza-Pérez & Huidobro-Campos, 2007 (Gulf angel shark)
  • Squatina japonica Bleeker
    Pieter Bleeker
    Pieter Bleeker was a Dutch medical doctor and ichthyologist, famous for his work on the fishes of East Asia – Atlas Ichthyologique des Orientales Neerlandaises – which was published 1862–1877....

    , 1858
    (Japanese angelshark)
  • Squatina legnota Last & W. T. White, 2008 (Indonesian angelshark)
  • Squatina mexicana Castro-Aguirre, Espinoza-Pérez & Huidobro-Campos, 2007 (Mexican angel shark)
  • Squatina nebulosa Regan, 1906 (Clouded angelshark)
  • Squatina occulta Vooren & K. G. da Silva, 1992 (Hidden angel shark)
  • Squatina oculata Bonaparte
    Charles Lucien Bonaparte
    Charles Lucien Jules Laurent Bonaparte, 2nd Prince of Canino and Musignano was a French naturalist and ornithologist.-Biography:...

    , 1840
    (Smoothback angelshark)
  • Squatina pseudocellata Last & W. T. White, 2008 (Western angelshark)
  • Squatina punctata
    Squatina punctata
    Squatina punctata, is an angel shark of the family Squatinidae found in the southwest Atlantic from southern Brazil to Argentina, at depths of from 10 to 80 m...

    Marini, 1936
  • Squatina squatina
    Squatina squatina
    The angelshark is a species of shark in the family Squatinidae , once widespread in the coastal waters of the northeastern Atlantic Ocean. Well-adapted for camouflaging itself on the sea floor, the angelshark has a flattened form with enlarged pectoral and pelvic fins, giving it a superficial...

    (Linnaeus
    Carolus Linnaeus
    Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...

    , 1758)
    (Angelshark)
  • Squatina tergocellata McCulloch
    Alan Riverstone McCulloch
    Alan Riverstone McCulloch was a prominent Australian ichthyologist.McCulloch was born in Sydney, and began his scientific career at the age of 13 as an unpaid assistant to Edgar Ravenswood Waite in the Australian Museum there; Waite encouraged McCulloch to study zoology...

    , 1914
    (Ornate angelshark)
  • Squatina tergocellatoides J. S. T. F. Chen, 1963 (Ocellated angelshark)

External links