One shark that is vanishing across its range
The Angelshark (Squatina squatina), is a shark belonging to the family Squatinidae. The Angelshark was called the Monkfish in the past. They were once widespread in the coastal waters of the northeastern Atlantic Ocean, but now are critically endangered due to a radical and rapid population decline and disappearance in some of its range locations. The Angelshark looks much like a ray or skate, but mostly like an angel due to its broad and flattened body, and enlarged pelvic and pectoral fins that look like wings. It is an ambush predator, and well-adapted to camouflage itself on the sea floor in sand or mud. This species can be identified by its broad and stout body, conical barbels, thorn-less back (in larger individuals), and grayish-red or brownish-green dorsal coloration with a pattern of numerous small light and dark markings (that is more vivid in juveniles). The Angelshark is much more nocturnally active than in the day.
Family: Squatinidae – Angel Sharks
Common Name– Angel Sharks or Angelsharks
Average Size and Length: The Angelshark is one of the largest members of its family. They are born between 9.4-11.8 inches. Mature females have been measured between 4.1-5.5 feet. The maximum recorded for a male has been recorded at 183 cm/ 6 feet. Research suggests females may reach 244 cm/ 8 feet.
Average Weight: The maximum reported weight is 180 pounds.
Current Rare Mythical Sightings: The Angelshark was originally described by the Swedish natural historian Carl Linnaeus, known as the “father of taxonomy”, in the 1758 tenth edition of Systema Naturae as Squalus squatina (later changed to Squatina squatina). He did not designate a type specimen. Squatina is the Latin word for skate. Bjorn Stelbrink and team in 2010 conducted a phylogenetic study based on mitochondrial DNA, and found that the sister species of the Angelshark is the Sawback angelshark (S. aculeata). The two species formed a clade with a number of Asian angelshark species.
Teeth and Jaw: The mouth is very wide and placed terminally. They have expendable necks and trap-like jaws that can rapidly snap upwards and hinge shut. They have long, needle-like teeth in the upper and in the lower jaws used for gripping.
Head: The nasal barbels have straight or spatulate tips. There are smooth or weakly fringed anterior nasal flaps. The lateral head folds have a singular triangular lobe on each side. The anterior lobes are not fused to the head. There are small eyes positioned dorsally and followed by a pair of larger spiracles. The gill openings are on the sides of the head.
Denticles: The dermal denticles are small, narrow, and pointed, and cover the entire upper and most of the lower body surface. There are small thorns on the middle of the snout and between the eyes.
Tail: The caudal fin has a larger lower lobe than upper.
Demographic, Distribution, Habitat, Environment and Range: The Angelshark can be found in the northeast Atlantic. Historically, they could be found from Norway to Mauritania, the Canary Islands, Mediterranean and the Black Sea (63°N – 21°N, 19°W – 42°E). However, due to population decline, they have disappeared from some of these areas within its range. They can be found in the mud or sand inshore around 16 feet on coasts and estuaries to greater than 492 feet on the continental shelf. They are considered marine, brackish, benthic, demersal and oceanodromous in temperate waters.
They are seasonally migratory in colder water, moving farther north in the summer. Aggregations numbering up to a hundred have been observed, but not confirmed, off Gran Canaria in the summer.
Diet: They eat flatfish, crustaceans, skates, and mollusks. There has been one record of an Angelshark swallowing a cormorant.
Ram-Suction Index: They have an RSI more towards the suction end of the scale. They lay flat and still on the bottom, when the time comes, they lung at prey and suck it into their mouths with negative pressure.
Aesthetic Identification: The Angelshark is one of the largest sharks of its family and is very stalky. It is grey to reddish or even greenish-brown dorsally, with scattered small white spots and blackish dots and spots. A white nuchal spot may be present. There are no ocelli. Juvenile sharks have white reticulations and large dark blotches. The adult sharks are much plainer in appearance. The dorsal fins have dark leading edges, with pale trailing edges. There are very high, broad pectoral fins. The pectoral and pelvic fins are wide with rounded tips; the two dorsal fins are positioned on the muscular tail behind the pelvic fins. The anal fin is absent.
Biology and Reproduction: The Angelshark is ovoviviparous, having between 7-25 pups per litter. The size of the litter is correlated with the size of the female, increasing with size. Gestation is anywhere between 8-10 months. Pups are born in December-February in the Mediterranean, and July in England. There are some suggestions that the reproductive cycle is 2 years, however this is not confirmed. The newborns measure between 9.4–11.8 inches long. Males and females mature at lengths of 2.6–4.3 feet and 4.3–5.6 feet.
The marine leech, Stibarobdella macrothela is a common parasite, and the isopod Aegapheles deshaysiana a common micropredator for this shark in the Canary Islands.
Behavioral Traits, Sensing and Intelligence: The Angelshark is lethargic by day and lies buried still in the mud or in the sand mud with only their eyes distended out, waiting to ambush prey. They are nocturnally active, energetically and strongly swimming at night.
Individual sharks actively choose ideal ambush sites, where they stay for several days before moving on to a new one. The prey learns to avoid the areas.
They detect weak electric fields generated by other organisms.
Angelsharks have a unique way of breathing compared to most other benthic sharks and fish. They do not pump out water from the oropharyngeal cavity. Instead, they use gill flaps located on the sides of their body to pump out water during respiration. Doing so also allows them to be more unnoticeable and prevent detection from unwanted predators.
Angelshark Future and Conservation: Since the mid-20th century, the Angelshark has been heavily commercially fished, and taken as bycatch. The Angelshark is considered highly valuable. They are slow to reproduce. Due to the heavy population decline in much of its range, the Angelshark population is unstable, and they are critically endangered. In Britain it is legally protected. In 2008, the Angelshark received full legal protection from human activities in the waters off England and Wales from the coast to a distance of 6.8 miles, under the UK Wildlife and Countryside Act. Since 2010, it has been illegal to keep Angelsharks caught in waters of the European Union (if caught, it must be released). The United Kingdom and Belgium have pushed, unsuccessfully, for this species to be listed on the Convention for the Protection of the Marine Environment of the North-East Atlantic Priority List of Threatened and Endangered Species. A captive breeding program has been initiated at Deep Sea World, North Queensferry, with the first live pups born in 2011. In 2019, a population of Angelsharks was discovered off the coast of Wales, indicating that the species had begun a potential return to the region.
People have used the Angelshark for thousands of years. Ancient Greek authors, such as Diphilus and Mnesitheus, described its meat as “light” and “easily digestible”, and Pliny the Elder noted in his Naturalis Historia (77–79 AD) that its rough skin was valued by craftsmen for polishing wood and ivory. Aristotle recorded elements of its natural history, including that it bore live young, and correctly recognized that it was a shark despite its resemblance to rays and skates. The use of Angelsharks for food has continued into modern times; it is sold fresh or dried and salted, often under the name “monkfish” (which also refers to the goosefishes of the genus Lophius). The Angelshark may also be a source for shark liver oil and fishmeal.
Angelshark Recorded Attacks on Humans: Angelsharks aren’t dangerous to humans unless provoked. Because of their powerful jaws and sharp teeth, they can inflict injury on anyone or anything that may pose a threat to them. There have been cases of Angel sharks biting divers that have tried to restrain them, approach too close to the head, corner them, or grab their tails.