Angel sharks are a distinctive group of cartilaginous fish, recognized by their remarkably flattened bodies and broad, wing-like pectoral and pelvic fins, which give them a resemblance to rays. Their eyes are positioned on the top of their wide heads, and their gill slits are located in front of their pectoral fins. These unique sharks are specialized ambush predators, relying on their appearance and behavior to capture prey. They typically remain motionless, often partially or fully buried in sand or mud, using their camouflage to blend with the seabed as they await unsuspecting prey.
Geographic Distribution
Angel sharks occur across the globe in both temperate and tropical marine environments, primarily inhabiting continental shelves. The common angel shark (Squatina squatina) has a historical distribution spanning the northeastern Atlantic Ocean, from the southern coasts of Norway and the British Isles, throughout the Mediterranean Sea, and south to Morocco. While historically widespread, intense fishing pressures have caused a significant contraction of its range, with the Canary Islands now serving as a crucial refuge where the species is still regularly encountered.
The Pacific angel shark (Squatina californica) is found along the eastern Pacific Ocean, with its range extending from southeastern Alaska to the Gulf of California, and potentially as far south as Ecuador and Chile. The sawback angel shark (Squatina aculeata) also inhabits the Mediterranean Sea and eastern Atlantic from Morocco to Angola. While some angel shark species possess broad geographical ranges, many others exhibit more localized distributions, often linked to their sedentary, bottom-dwelling habits, which make extensive trans-oceanic migrations unlikely.
Specific Habitat Preferences
Angel sharks are predominantly bottom-dwelling creatures, favoring specific seafloor characteristics that support their predatory lifestyle. They commonly inhabit sandy, muddy, or gravelly bottoms, and can also be found in seagrass beds or near rocky reefs. Their flattened body shape and mottled coloration provide exceptional camouflage, allowing them to lie nearly invisible against the ocean floor. They often bury themselves in the sediment, with only their eyes and specialized gill openings (spiracles) exposed, patiently waiting to ambush prey.
These sharks maintain their stationary position by continuously pumping water over their gills, enabling them to remain perfectly still for extended periods. They are typically found in shallow coastal waters, with most species residing at depths ranging from a few meters down to about 150 meters. However, some angel shark species can inhabit much deeper environments, descending to depths of up to 1,300 meters. Their preferred habitats include bays, estuaries, and coastal shelves, where water temperatures are generally temperate or tropical. Water temperature influences their behavior; for instance, female common angel sharks may avoid mating grounds if temperatures exceed 22.5°C.
Regional Species Diversity
The genus Squatina encompasses at least 22 to 24 distinct species of angel sharks, each with its own specific, though sometimes overlapping, regional distributions. This extensive diversity means different species have adapted to varied ecological niches and habitats.
For instance, the Pacific angel shark (Squatina californica), while broadly distributed along the eastern Pacific, is particularly common off the coasts of central and southern California, often favoring habitats near rocky reefs and kelp forests. This contrasts with species like the sawback angel shark (Squatina aculeata), which typically prefers deeper continental shelf and upper slope sediment habitats. The sawback is commonly found between 30 and 500 meters, though it has been recorded at depths of 1,400 meters, showcasing the significant depth preferences among angel shark species. Understanding these specific habitat preferences is crucial for conservation efforts, as each species may face unique threats within its specialized environment.