SQUATINIDAE ANGEL SHARKS
The Squatinidae, or common name Angel Sharks (or Angelsharks) are a family belonging to the order Squatiniformes, also known as the Angel Sharks. There is only one genus in with the family, Squatina, with around 24 species.
Squatinidae are quite unique looking. They have flattened bodies and broad, triangular pectoral fins that give them a similar appearance to rays. The rear has a muscular appearance. The eyes and spiracles are on top and the five gill slits are on its back. Both the pectorals and the pelvic fins are large and are horizontally origin. There are two dorsal fins, no anal fin and the lower lobe of the caudal fin is longer than the upper lobe. They can grow on an average of 5 feet in length.
Angel sharks have a unique way of breathing compared to most other benthic sharks and fish. They do not pump out water from the oropharyngeal cavity. Instead, they use gill flaps located on the sides of their body to pump out water during respiration. Doing so also allows them to be more unnoticeable and prevent detection from unwanted predators.
Angel sharks have very large mouths. They have nostrils with barbels on the anterior nasal flaps. Their expendable necks and trap-like jaws can rapidly snap upwards and hinge shut to capture prey. They have long, needle-like teeth perfect for gripping. Angel sharks are ambush predators, and bury themselves in sand or mud lying while they wait for prey. They eat fish, crustaceans and various types of mollusks. Angel sharks have an RSI more towards the suction end of the scale. They lie on the bottom completely camouflaged and motionless, they lunge at passing prey, and suck prey into their mouths with negative pressure. Since they must blend into their bottom environments, many have unique patterns above, and mostly pale below, making them extremely beautiful to see.
Angel sharks can be found worldwide in cool, temperate and tropical seas over continental shelves (intertidal to continental slopes). If in tropical waters, they are found to inhabit deeper water, some down as deep as 4,300 feet. They are mostly absent in the Indian Ocean and the central Pacific Ocean. Research suggests that they do not swim long distances or venture far at all.
Angel sharks are ovoviviparous, and have between 1-25 pups per litter. Not much is known about their reproduction, but research suggests there may be differences by location.
Some species are very difficult to tell apart from one another. In the past Angel sharks were known as monkfish, and before the 1980’s, one species in particular, the Pacific angelshark, was considered to be a monkfish.
Scientifically, morphological ID in the field can be to a great degree troublesome thinking about discontinuity of species for exchange or high likeness between congeneric species. DNA barcoding was utilized in an examination to track potential wrongdoings against the arrival and exchange of imperiled species along the Sao Paulo coastline, specifically Squatina guggenheim (n = 75) and S. occulta (n = 5), and also the Brazilian guitarfish Pseudobatos horkelii (n = 5). DNA barcoding uncovered the ceaseless angling and trafficking of these ensured species, subsequently giving clear proof that the present protection models and strategies for observing are not working. (“The fishing and illegal trade of the angelshark: DNA barcoding against misleading identifications“. Fisheries Research. ScienceDirect. 2018. pp. 193–197.)
Angel sharks aren’t dangerous to humans unless provoked. Because of their powerful jaws and sharp teeth, they can inflict injury on anyone or anything that may pose a threat to them. There have been cases of Angel sharks biting divers that have tried to restrain them, approach too close to the head, corner them, or grab their tails.
In 1977, Michael Wagner, a fish processor in Santa Barbara, California, in cooperation with local commercial fisherman, developed the market for angel sharks. The annual take of angel shark in 1977 was an estimated 324 pounds. By 1985, the annual take of angel shark on the central California coast had increased to more than 454 metric tons or an estimated 90,000 sharks. The population declined dramatically and is now regulated. In April 2008, the UK government presented the Angel shark full protection under the Wildlife and Countryside Act. In 2010, a once abundant species of Angel shark, the Angelshark, Squatina squatina, was labeled critically endangered. (Richards, J.B. (1987) “Developing a localized fishery: the pacific angel shark”. Sharks: An Inquiry into Biology, Behavior, Fisheries, and Use. Cook, S. (Eds.) EM 8330: 147-160).