Squatiniformes is the scientific order that contains all angel sharks, a group of flat-bodied, bottom-dwelling sharks that look far more like rays than anything most people picture when they hear the word “shark.” The order holds a single family (Squatinidae) and a single living genus, Squatina, with roughly 22 recognized species spread across warm-temperate and tropical continental shelves worldwide. Despite their unusual shape, angel sharks are true sharks with cartilaginous skeletons and gill slits, and their evolutionary lineage is ancient. What makes them especially interesting today is a combination of strange biology, an ambush-hunting lifestyle unlike almost any other shark, and a conservation crisis so severe that several species have lost more than half their historical range.
What Angel Sharks Look Like and Why They Are Easy to Misidentify
An angel shark’s body is dorsoventrally flattened, meaning it is compressed from top to bottom rather than side to side. The pectoral fins extend outward like broad wings, and the head blends almost seamlessly into the body, giving the animal a silhouette that strongly resembles a skate or ray. The mouth is positioned at the front of the head rather than underneath it, a trait unusual among sharks and useful for snatching prey off the seafloor. The eyes sit on top of the head, and conspicuous spiracles behind them help draw water in for respiration.
This body plan is an adaptation for life on the bottom. Angel sharks spend much of their time partially buried in sand or sediment, with only their eyes and spiracles exposed. Their coloring, usually mottled brown, grey, or sandy tones with irregular spots, serves as camouflage against the substrate. Because of the flat shape and the habit of lying motionless on the seabed, divers and fishers sometimes mistake angel sharks for rays, and historically some cultures grouped them together. But angel sharks are phylogenetically distinct: molecular analyses confirm the genus Squatina is monophyletic, meaning all living angel sharks descend from a single common ancestor within the shark lineage rather than being related to rays.
Stealth Breathing
Most bottom-dwelling fish breathe by rhythmically expanding and contracting the cavity inside their mouth and throat to pump water over the gills. Angel sharks do something different. Sonographic studies of angelshark respiration found that they do not use the mouth-and-throat pumping mechanism at all. Instead, breathing motion is restricted to gill flaps on the underside of the body, which actively push water out through the gill slits from below.
This matters because it keeps the shark’s cover intact. If an angel shark lying buried in sand had to visibly open and close its mouth to breathe, predators or prey would notice the movement. By confining all respiratory motion to the ventral surface, hidden beneath the body and the sediment, the shark can breathe without giving itself away. Researchers have described this as increasing the animal’s “crypsis capacity,” which is a formal way of saying it helps the shark stay invisible.
How Angel Sharks Hunt and What They Eat
Angel sharks are ambush predators. They settle onto the seafloor, wriggle into the sediment until only their eyes are visible, and wait. When a fish or other prey animal passes within striking distance, the shark lunges upward in a rapid, jaw-extending snap that can happen in a fraction of a second. The upward-facing mouth and the protrusible jaw are key to this strike: the shark does not chase its prey so much as explode out of the sand beneath it.
Diet studies show that bony fishes make up the vast majority of what angel sharks eat. In one detailed study of the angular angel shark (Squatina guggenheim) off Uruguay and northern Argentina, bony fishes accounted for about 90% of prey items by number. The single most important prey species was the Argentine anchovy, which alone made up over half the diet. Crustaceans like shrimp and cephalopods like squid filled out most of the remainder, each contributing a few percent.
This dietary profile makes sense for a sit-and-wait predator living on continental shelves. Small schooling fish like anchovies pass over the substrate in large numbers, giving a buried shark frequent opportunities. The relatively minor contribution of crustaceans and squid suggests these are likely opportunistic catches rather than primary targets.
Reproduction and Growth
Angel sharks are ovoviviparous, meaning embryos develop inside eggs that are retained within the mother’s body until the pups are born live. This is a common reproductive mode among sharks, but the specifics vary by species in ways that matter for conservation.
In the Atlantic angel shark (Squatina dumeril) off the eastern United States, females have only one functional ovary (the left one), and average litter size is about seven pups. Gestation runs roughly 12 months, and births tend to happen in spring, from around February through June. The angular angel shark off South America has somewhat smaller litters, ranging from two to eight embryos with an average around four. In that species, larger females tend to produce more offspring, a pattern common in sharks generally.
These numbers point to a fundamental vulnerability. A species that produces only a handful of young per year, after a full year of gestation, cannot bounce back quickly from population declines. Compare that to a bony fish that might release hundreds of thousands of eggs in a single spawning event. When fishing pressure or habitat loss reduces angel shark numbers, recovery takes decades even under ideal conditions.
Where Angel Sharks Live
Angel sharks are found in warm-temperate to tropical waters on continental shelves around the world, including the eastern Atlantic, the Mediterranean, the western Atlantic from New England to Argentina, and parts of the western Pacific and Australian waters. Many species exhibit seasonal inshore-offshore migrations, moving into shallower coastal waters to give birth and then retreating to deeper shelf waters afterward.
The common angelshark (Squatina squatina) has the northernmost range of any angel shark species, historically extending from Scandinavia and the British Isles down through the Mediterranean and along the West African coast. A detailed study of this species in Welsh coastal waters compiled over 2,200 records dating back to 1812 and found that the overwhelming majority of sightings occurred within about 11 kilometers of the coast. Distribution modeling identified depth, sea surface temperature, salinity, and chlorophyll concentration as the key environmental factors influencing where the sharks showed up, and the data suggested a seasonal pattern: angel sharks moved into shallower, warmer, less saline coastal waters during spring and summer.
A Conservation Crisis
Several angel shark species are among the most threatened sharks on Earth. Three species in the eastern Atlantic and Mediterranean, the common angelshark (Squatina squatina), the sawback angelshark (S. aculeata), and the smoothback angelshark (S. oculata), are all classified as Critically Endangered by the IUCN. Research mapping their historical versus contemporary distributions found that severe population declines have led to a near-halving of the geographic range of all three species. The common angelshark lost an estimated 58% of its range, the sawback about 51%, and the smoothback about 48%.
The primary driver of these declines is fishing, particularly bycatch. Angel sharks were historically caught both as target species and as unintended bycatch in bottom trawls, gillnets, and longlines. Their habit of lying flat on the seafloor makes them especially vulnerable to trawl nets that scrape along the bottom. A survey of artisanal fishers in Libya found that trawling was the gear type most commonly associated with angel shark capture, cited by over 43% of respondents, followed by bottom gillnets at about 36% and longlines at roughly 21%. Because angel sharks reproduce slowly, even moderate, sustained fishing mortality can push populations into decline.
Protective measures have been growing. An inventory of legal protections found that the common angelshark alone is subject to 20 international, regional, and national protection measures, though the sawback and smoothback lag behind, covered by only about 11 such measures. However, paper protections do not always translate into on-the-water enforcement, and bycatch remains difficult to eliminate as long as the fishing gears that catch angel sharks are still in use in their habitats.
The Canary Islands as a Last Stronghold
For the common angelshark, the Canary Islands off the northwest coast of Africa have emerged as the most important remaining population center globally. Citizen science programs in the archipelago have gathered extensive sighting data, revealing that the islands host both adults and neonates, with larger individuals and newborns most commonly observed from April through July during the pupping season. Very small angel sharks, the neonates, were found exclusively in shallow water less than 25 meters deep.
Specific beaches have been identified as nursery habitat. Long-term monitoring at Las Teresitas on Tenerife found year-round presence of newborn and young-of-the-year angel sharks, with repeated recaptures and extended use of the site by individual animals. This provides strong evidence that the beach functions as a genuine nursery, a place where pups are born and spend their early life rather than just passing through. Protecting these nursery areas has been identified as a high-priority conservation action because maintaining recruitment of young sharks into the population is essential for any chance of recovery.
Researchers have also focused on identifying and safeguarding juvenile habitat across the Canary Islands more broadly, recognizing that the loss of even one key nursery site could undermine the population’s ability to sustain itself.
Genetic Fragmentation Between Islands
One of the more concerning findings from recent research is that angel shark populations in the Canary Islands are not one big, well-connected group. Genetic studies using both mitochondrial and nuclear markers have identified at least three distinct management units within the archipelago: one around Tenerife, one around Gran Canaria, and one spanning the easternmost islands of La Graciosa, Lanzarote, and Fuerteventura. There is significant genetic differentiation between these units, meaning the sharks from different island groups are not interbreeding freely.
The likely barrier is the deep water between islands. Angel sharks are bottom-dwellers that stick to continental shelf depths, and the abyssal channels separating some Canary Islands may be effectively uncrossable for them. Seasonal upwelling patterns and the varying geological history of each island also play a role in shaping connectivity. The practical implication is that conservation plans cannot treat the Canary Islands as a single population. If the Tenerife group declines, it cannot be easily “rescued” by immigrants from Gran Canaria or Lanzarote, because those sharks rarely if ever make the crossing.
A similar picture of genetic vulnerability has emerged from the Mediterranean. Genomic analysis of angel sharks off Corsica, another key refuge, found relatively low genetic diversity in that population, with observed heterozygosity around 0.115 across 100 sampled individuals. Low diversity suggests a small effective population size, which makes the population more susceptible to inbreeding depression and less able to adapt to changing conditions. The finding reinforces the idea that these isolated refuges, while critically important, are also fragile.
Marine Protected Areas and the Gap in Coverage
On paper, angel sharks benefit from a growing web of international and regional protections. In practice, the overlap between where angel sharks actually live and where marine protected areas (MPAs) exist is often poor. A spatial conservation analysis in the northeastern Mediterranean, focusing on the Aegean Sea and waters around Crete, found low overlap between the existing MPA network and the areas most critical for angel shark distribution, particularly in Greek and Turkish waters. About 20% of the critical areas for angel shark distribution overlapped with Fisheries Restricted Areas, but dedicated shark-focused MPAs in the Mediterranean are essentially nonexistent.
The Regional Action Plan for Mediterranean Angel Sharks has identified the Aegean Sea and Crete as critical areas for all three eastern Atlantic and Mediterranean species. But identifying priority areas and actually protecting them are different things. The policy recommendations from researchers consistently call for creating MPAs specifically designed around angel shark habitat, enforcing existing fishing restrictions more rigorously, and engaging local fishing communities as stakeholders in conservation rather than treating them as adversaries. Whether those recommendations translate into action quickly enough to prevent further range loss remains an open question.
Angel Sharks and Humans
Angel sharks pose virtually no danger to people. They are not aggressive, and encounters are rare since the animals spend most of their time buried and invisible. The main risk is accidentally stepping on one in shallow water, which can provoke a defensive bite. Those bites, while painful and capable of causing a wound, are not life-threatening. Divers who spot angel sharks on the sand are generally advised to keep a respectful distance and avoid disturbing the animal.
Historically, angel sharks were fished commercially in several parts of their range. In California, the Pacific angel shark (Squatina californica) supported a substantial fishery in the 1980s before catches declined and regulations were imposed. In the Mediterranean, angel sharks were caught in mixed-species bottom trawl fisheries for centuries. The animals’ flat shape made their skin useful as a rough abrasive material, sometimes called “shagreen,” which was used for polishing wood and other surfaces before sandpaper became widely available. The name “angel shark” itself likely comes from the wing-like pectoral fins, though some historical sources suggest it derives from monkish associations, and the French name “ange de mer” (sea angel) reinforces the wing imagery.
Parasites and What They Reveal
Like most marine animals, angel sharks host parasites, and studying those parasites can offer indirect insights into the sharks’ ecology. One documented parasite is the marine leech Stibarobdella moorei, which has been collected from angel sharks caught by trawl vessels in Antalya Bay, Turkey, at depths around 50 meters. The leeches attach to the dorsal surface and create two types of lesions on the skin: a larger wound from the oral sucker and a smaller one from the caudal sucker. This particular leech species had not previously been reported from elasmobranchs in Turkish Mediterranean waters, so the finding expanded the known host-parasite range for both species.
Parasite records like this are more useful than they might seem. They confirm where angel sharks are present (the Antalya Bay finding adds a data point for Mediterranean distribution), and they reveal something about the sharks’ benthic lifestyle: parasites that attach to the upper body surface are consistent with an animal that spends long periods lying still on the bottom, exposed dorsal-side-up. Parasite diversity and load can also serve as rough indicators of population health, though that line of research is still in its early stages for angel sharks.