The order Squatiniformes, known by the common name angel sharks, represents a unique lineage of at least 22 distinct shark species. These animals are recognizable by their flattened bodies and broad fins, an appearance that often causes them to be confused with rays. They are bottom-dwellers that spend most of their lives on the seafloor in oceans around the globe.
Distinctive Anatomy and Appearance
Angel sharks have flattened bodies with expansive pectoral and pelvic fins that look like wings, which is the source of their common name. Despite this ray-like appearance, their pectoral fins are not fused to their heads, a trait characteristic of rays. Their five gill slits are located on the sides of the head, just in front of the fins.
Their mouth is located at the very front of the snout, a position known as terminal, which is suited for their method of feeding. The skin is covered in dermal denticles, giving it a texture similar to sandpaper, and their coloration is a mix of mottled grays and browns. This coloring provides effective camouflage against the sandy and muddy bottoms where they live. On their tail, they have two small dorsal fins but lack an anal fin.
Habitat and Hunting Behavior
These sharks are found in the benthic zones of temperate and tropical waters worldwide, living on continental shelves. They show a strong preference for habitats with soft, sandy, or muddy bottoms. They can be found in shallow coastal waters, sometimes just a few meters deep, to depths of around 150 meters.
Angel sharks are ambush predators that employ patience and camouflage. They bury themselves in the sediment, leaving only their eyes and spiracles exposed. The spiracles, located behind the eyes, are respiratory openings that allow them to pump water over their gills while remaining stationary. As primarily nocturnal hunters, they lie in wait for extended periods until suitable prey ventures too close. When a target is in range, they strike with incredible speed, their extensible jaws snapping upwards to capture the meal.
Diet and Reproduction
Angel sharks primarily consume small bony fishes, especially flatfishes, along with various crustaceans and mollusks that inhabit the seafloor. Their prey includes crabs, squid, and skates, with some regional variation in their diet based on local prey availability.
Reproduction in angel sharks occurs through ovoviviparity. This means the embryos develop inside eggs that are retained within the mother’s body, and she gives birth to live, fully-formed pups. There is no placental connection; the pups are nourished by the yolk sac of their egg. A single female can give birth to a litter ranging from seven to 25 pups.
Conservation Status and Threats
More than half of all known angel shark species are listed as endangered or critically endangered by the International Union for Conservation of Nature (IUCN). The common angel shark (Squatina squatina), once widespread, is now considered critically endangered and has vanished from large parts of its historic range, such as the North Sea. Populations have declined so severely that the family Squatinidae is considered the third most threatened family of elasmobranchs.
The primary threat to angel sharks is bycatch from commercial fishing operations. Their bottom-dwelling nature makes them particularly vulnerable to being unintentionally caught in bottom trawls and set nets. Habitat degradation from coastal development also contributes to their decline. Their low reproductive rates mean that populations are very slow to recover from these pressures, making them highly susceptible to rapid local depletions.