Squatina Squatina

''Squatina squatina'', the angelshark or monkfish, is a species of shark in the family Squatinidae (known generally also as angel sharks), that were 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 resemblance to a ray. This species can be identified by its broad and stout body, conical barbels, thornless back (in larger individuals), and grayish or brownish dorsal coloration with a pattern of numerous small light and dark markings (that is more vivid in juveniles). It measures up to long.

Like other members of its family, the angelshark is a nocturnal ambush predator that buries itself in sediment and waits for passing prey, mostly benthic bony fishes, but also skates and invertebrates. An aplacental viviparous species, females bear litters of seven to 25 pups every other year. The angelshark normally poses little danger to humans, though if provoked, it is quick to bite. Since the mid-20th century, intense commercial fishing across the angelshark's range has decimated its population via bycatch – it is now locally extinct or nearly so across most of its northern range, and the prospects of the remaining fragmented subpopulations are made more precarious by its slow rate of reproduction. As a result, the International Union for Conservation of Nature has assessed this species as Critically Endangered.

Taxonomy and phylogeny

The angelshark was originally described by the Swedish natural historian Carl Linnaeus, known as the "father of taxonomy", in the 1758 tenth edition of ''Systema Naturae'' as ''Squalus squatina''. He did not designate a type specimen. The word ''squatina'' is the name for skate in Latin; it was made the genus name for all angel sharks by the French zoologist André Duméril in 1806. Other common names used for this species include angel, angel fiddle fish, angel puffy fish, angel ray, angelfish, escat jueu, fiddle fish, monk, and monkfish. Stelbrink and colleagues (2010) conducted a phylogenetic study based on mitochondrial DNA, and found that the sister species of the angelshark is the sawback angelshark (''S. aculeata''). The two species formed a clade with a number of Asian angelshark species.

Description

One of the largest members of its family, female angelsharks can attain a length of and males ; the maximum reported weight is . This species shares in common with other angelsharks a flattened body and large, wing-like pectoral fins whose anterior lobes are not fused to the head. The head and body are very broad and stocky, with small eyes positioned dorsally and followed by a pair of larger spiracles. A pair of unadorned barbels occurs in front of the nares, as well as a smooth or weakly fringed flap. Folds of skin with a single triangular lobe are present on the sides of the head. The teeth are small, sharp, and of similar shape in both jaws.

The pectoral and pelvic fins are wide with rounded tips; the two dorsal fins are positioned on the muscular tail behind the pelvic fins. The anal fin is absent, and the caudal fin has a larger lower lobe than upper. The dermal denticles are small, narrow, and pointed, and cover the entire upper and most of the lower body surface. There are patches of small spines on the snout and over the eyes. Small individuals have a row of thorns down the middle of the back. The coloration is gray to reddish or greenish brown above, with many small black and white spots, and white below. Juveniles are more ornately patterned than adults, with pale lines and darker blotches. The dorsal fins have a darker leading margin and lighter trailing margin. Some individuals have a white spot on the back of the "neck".

Distribution and habitat

The angelshark occurs in the temperate waters of the northeastern Atlantic, from southern Norway and Sweden to the Western Sahara and the Canary Islands, including around the British Isles and in the Mediterranean. According to the IUCN, it is possible that it has been extirpated from the North Sea. It remains extant around the Canary Islands, Algeria, Tunisia, Libya, Israel, Turkey, northern Cyprus, eastern Greece (the Aegean Sea), the Adriatic Sea of eastern Italy, Sicily, Malta, Corsica, Ireland and western Britain/Wales
. Its modern presence in parts of the Mediterranean is unknown, such as around Madeira, the Azores, Morocco, Egypt, continental Spain and France, Crete, Syria, Sardinia, western Greece and western Italy. This benthic shark inhabits the continental shelf, preferring soft substrates such as mud or sand, and can be found from near the coast to a depth of . It sometimes enters brackish environments. Northern angelshark subpopulations migrate northward in summer and southward in winter.

Biology and ecology

During daytime, the angelshark usually lies motionless on the sea floor, buried under a layer of sediment with only its eyes showing. At night, it becomes more active, and may sometimes be seen swimming above the bottom. Aggregations numbering up to a hundred have been observed off Gran Canaria in the summer.Murch, A
Common Angel Shark Information and Pictures
Elasmodiver.com. Retrieved on July 8, 2009. Known parasites of this species include the tapeworms ''Grillotia smaris-gora'', ''G. angeli'', and '' Christianella minuta'', the fluke ''Pseudocotyle squatinae'', the monogenean ''Leptocotyle minor'', and the isopod ''Aega rosacea''.

The angelshark is an ambush predator that feeds mainly on bottom-dwelling bony fishes, especially flatfishes, though it also preys on skates and invertebrates. Prey reported taken include the hake ''Merluccius merluccius'', the bream ''Pagellus erythrinus'', grunts in the genus ''Pomadasys'', the flatfishes ''Bothus'' spp., '' Citharus linguatula'', and ''Solea solea'', the squid ''Loligo vulgaris'', the cuttlefishes ''Sepia officinalis {{redire ...