Squatinidae
Squatinidae is a family of sharks commonly known as angel sharks. These flattened sharks are well-adapted for life on the seabed and resemble rays in appearance. Angel sharks can be found in temperate and subtropical waters worldwide. They are a group of sharks that are relatively ancient, having first appeared in the Late Jurassic period.
Characteristics
Angel sharks have a distinctive flattened body shape with a broad, triangular head and large, forward-facing eyes. Their pectoral fins are broad and wing-like, giving them their common name. They have small, pointed dorsal fins, a small anal fin, and a short, stout tail. Their skin is covered with small, rough scales, and some species have a row of spines along the midline of their back. Angel sharks are typically colored in shades of brown or grey, often with mottled or spotted patterns.
Environment
Angel sharks are demersal, meaning they live on the seabed. They are found in a variety of habitats, including sandy bottoms, rocky reefs, and kelp forests. They prefer depths ranging from the shallows to over 1000 meters. Some species are known to be found in estuaries and brackish waters.
Reproduction
Angel sharks are oviparous, meaning they lay eggs. The females lay eggs encased in a tough, leathery capsule that is often attached to seaweed or rocks. The embryos develop within the egg capsule and are nourished by a yolk sac. When they hatch, they are already relatively large and capable of swimming.
Diet
Angel sharks are ambush predators that feed on a variety of fish, crustaceans, and cephalopods. They lie in wait on the seabed, camouflaged amongst the rocks or sand, and then launch a sudden attack on their prey. Their powerful jaws and sharp teeth are well-suited for crushing the shells of crustaceans and the bones of fish.
Conservation Status
Many species of angel sharks are facing threats from overfishing, habitat destruction, and pollution. Their slow reproductive rate and their tendency to congregate in shallow waters make them particularly vulnerable to fishing pressure. As a result, several angel shark species are classified as vulnerable or endangered by the International Union for Conservation of Nature (IUCN).
Species
There are currently 12 recognized species of angel sharks, divided into two genera: Squatina and Squatinella. The most common species include:
- Squatina squatina (Common angel shark)
- Squatina aculeata (Spiny angel shark)
- Squatina californica (California angel shark)
References
For further information on Squatinidae, please refer to the following websites:
- FishBase
- IUCN Red List
- Elasmo Research Organization