The Taiwan angelshark (''Squatina formosa'') is an

angelshark The angelsharks are a group of sharks in the genus ''Squatina'' of the family Squatinidae. They commonly inhabit sandy seabeds close to in depth. Many species are now classified as critically endangered by the International Union for Conservat ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Squatinidae. The Taiwan angelshark is one of four species of Squatina in the waters around

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the northe ...

and Japan. It is a

demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a laye ...

, ray-like shark that grows to 1–2 meters in length.

Taxonomy

The genus '' Squatina'' is the only genus in the monogeneric family Squatinidae. The Taiwan angelshark was described in 1972 and named after the historic name for Taiwan, "

Formosa Taiwan, officially the Republic of China (ROC), is an island country located in East Asia. The main island of Taiwan, formerly known in the Western political circles, press and literature as Formosa, makes up 99% of the land area of the territori ...

Description

Taiwan angelsharks are

ray Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (gra ...

-like sharks. Since they are

sharks and spend most of their time resting on the sediment, their eyes and spiracles are located

dorsally Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

. The dorsal surface is covered in somewhat rough

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as w ...

s. The overall shape of the head is rounded and about 20 percent of the total body length. The widest part of the head is just before the gill openings. The species has

tubercle In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projection ...

s between the mouth and eyes. Its teeth are small and cone-like without serrations, forming three rows. Taiwan angel sharks have large, broad pectoral fins, spineless dorsal fins, no anal fins, and a caudal fin that is hypocercal (the lower lobe is larger and more pronounced than the upper lobe). Both dorsal fins are lobed and are approximately the same size. An adult Taiwan angel shark can grow to be up to 2 m in length. Growth is generally slow and maturity happens late in life. Reproduction is

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

. Like other benthic sharks, is dark in coloration, brown with many black and white splotches on the dorsal side. The abdomen is lighter, pale white, with black splotches.

Distribution and habitat

Taiwan angelsharks are

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

to the waters of the continental shelf off Taiwan, between

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north po ...

s 20° N and 24° N). They occur at depths of 100–300 m, sometimes in shallower waters. The species is an

ambush predator Ambush predators or sit-and-wait predators are carnivorous animals that capture or trap prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey u ...

and buries itself in the sediment to wait for prey to come into range.

Conservation

The Taiwan angelshark is classified as

Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

by the IUCN, based on suspected population declines of 50-80% within its limited range. While it is not a target of fisheries, it is a frequent and generally retained

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juven ...

bottom trawling Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is tow ...

. Its entire range coincides with the extent of Taiwan's main fisheries (including longline and gillnetting). As the species is slow-maturing and has relatively few offspring, it is thought to be heavily impacted by this constant exploitation. No active conservation measures are currently in place.

References

* {{Taxonbar, from=Q28872 Taiwan angelshark Fish of Taiwan Taiwan angelshark