The Angel Shark (Squatina) is a unique group of flattened sharks often mistaken for rays due to their broad, wing-like pectoral fins. These unusual elasmobranchs are the sole members of the order Squatiniformes, possessing a body shape unlike most other sharks. Understanding their specialized habitat preferences is intrinsically linked to their survival, as these preferences dictate their distribution and vulnerability.
Understanding the Angel Shark’s Benthic Habitat
Angel sharks are strictly benthic, meaning they are permanent bottom-dwellers. They prefer soft sediment substrates, such as sandy or muddy bottoms, which allow them to practice their specialized ambush predation strategy. During the day, they remain motionless, partially burying themselves in the substrate with only their eyes and spiracles visible. This highly effective camouflage enables them to wait for unsuspecting prey.
They are typically found in shallow coastal waters, bays, and estuaries, ranging from the surf zone down to the edge of the continental shelf. Most species inhabit depths between 1 and 200 meters, though some have been recorded as deep as 1,300 meters. This preference for flat, easily accessible shelf environments shapes their distribution and contributes to their sedentary nature and high site fidelity.
Global Distribution Across Major Ocean Basins
The Squatina genus is distributed worldwide across temperate and tropical marine environments. Angel sharks are well-represented in the Eastern Atlantic Ocean, extending from Norway southward to West Africa, including the Mediterranean Sea. The genus also has a strong presence along the coasts of the Americas in both the Eastern Pacific and Western Atlantic basins.
The genus is largely absent from the open Indian Ocean and the central regions of the Pacific Ocean. This global pattern suggests a preference for continental shelf habitats rather than deep-sea environments or trans-oceanic migration. Their presence is concentrated in coastal zones where the sea floor is relatively shallow and composed of suitable soft sediments.
Localized Ranges of Key Species
The overall distribution fragments into highly localized ranges when examined at the species level. The common Angelshark (Squatina squatina) provides a stark example of range contraction in the Eastern Atlantic. This species was historically found along the entire European coastline, from southern Scandinavia to the Mediterranean and the Black Sea. Today, this population is severely fragmented and considered locally extinct in the North Sea and much of the Mediterranean.
The last remaining stronghold for S. squatina is concentrated around the Canary Islands, where it is still regularly sighted in shallow, coastal waters. In the Eastern Pacific, the Pacific Angel Shark (Squatina californica) occupies a restricted range along the western coast of North and South America. Its distribution stretches from the Gulf of California up to Southeast Alaska, with populations most common off the coast of Southern California.
The Mediterranean Sea, which once hosted a diverse population, now contains three critically endangered species (S. squatina, S. aculeata, and S. oculata). Their persistence is limited to isolated pockets, such as the northern Adriatic and parts of the Aegean Sea. These examples highlight how ranges vary dramatically, from historical continental scales to current, highly restricted island habitats.
The Link Between Location and Conservation Status
The localized, bottom-dwelling nature of Angel Sharks is the primary reason for their extreme vulnerability to human activities. Their preference for soft sediments on the continental shelf often overlaps directly with intensive fishing grounds. Because they spend the majority of their time camouflaged and motionless on the seabed, they are exceptionally susceptible to being caught as bycatch in demersal fishing gear.
The use of bottom trawling and fixed bottom nets in coastal areas has decimated populations across their historical range. For the common Angelshark, this threat has resulted in a documented range contraction of over 80% across the Northeast Atlantic. The Canary Islands population has persisted largely because a prohibition on trawling was implemented in the region in 1986.
This highly restricted geographic existence, combined with life history traits such as slow growth and low reproductive rates, makes them vulnerable. Localized habitat degradation therefore has an immediate and severe impact on the species’ survival.