SAWBACK ANGELSHARK
Beautiful patterned angel shark with a thorny dorsal side and fins that look like wings
The Sawback angelshark (Squatina aculeata) is an Angel shark belonging to the family Squatinidae. They can be found in the eastern Atlantic and western Mediterranean. They are uncommon and critically endangered. They have flattened bodies and broad, triangular pectoral fins that gives them an unmistakable appearance. Sawback angelsharks have white and brown blotches over their bodies, and large thorns on the head and in a row along the back, giving them their common name.
Family: Squatinidae – Angel Sharks
Genus: Squatina
Species: aculeata
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Infraclass– Euselachii
Superorder– Selachimorpha
Common Name– Angel Sharks or Angelsharks
Family– Squatinidae
Common Name– Angel Sharks or Angelsharks
Genus– Squatina
Species– aculeata
Status: IUCN Red List CRITICALLY ENDANGERED
Average Size and Length: On average, mature Sawback angelsharks are around 4.1 feet. The maximum recorded has been 6.2 feet.
Teeth and Jaw: Their mouths are very large. They have expendable necks and trap-like jaws that can rapidly snap upwards and hinge shut. They have long, needle-like teeth used for gripping.
Head: Sawback angelsharks do not have ocelli. The eyes and spiracles are placed on top. There is a concave area between the eyes. The eye to spiracle distance is less than 1.5 times the eye length. The anterior nasal flaps have barbels, and both have an abundance of fringe.
Denticles: There are large thorns on the head and in a row along the back.
Tail: The lower lobe of the caudal fin is longer than the upper lobe.
Demographic, Distribution, Habitat, Environment and Range: The Sawback angelshark can be found in the eastern Atlantic and western Mediterranean between 43°N – 19°S, 18°W – 30°E; Nigeria, Gabon to Namibia. They have also been spotted in Morocco, Senegal, Guinea, and Angola. They can be found offshore on the outer continental shelf and upper slope, typically in mud between 98-1,640 feet. They are considered demersal.
Diet: They feed on bony fishes, smaller sharks, crustaceans and cuttlefish.
Ram-Suction Index: They have an RSI more towards the suction end of the scale. They lie on the bottom completely camouflaged and motionless, they lunge at passing prey, and suck prey into their mouths with negative pressure.
Aesthetic Identification: Sawback angelsharks are dark grey or light brown on the dorsal side and are scattered with irregular white and brown spots that are small. There are large dark blotches on the head, back, fin bases and the tail. These blotches are camouflage, and allow the shark to appear as it if was sandy bottom with the reflection of moving water. Sawback angelsharks do not have ocelli.
The 5 gill slits are placed on the head. They have flattened bodies and broad, triangular pectoral fins that appear like wings. Both the pectorals and the pelvic fins are large and are horizontally origin. There are two dorsal fins and no anal fin.
Biology and Reproduction: Not much is known about the biology or reproduction of the Sawback angelshark, but they are presumably ovoviviparous with a litter size of between 8-12 pups. At birth, the neonate sharks are about 12.6 inches long and weigh about 10.6 ounces.
Behavioral Traits, Sensing and Intelligence: They are ambush predators. They bury themselves in sand or mud lying while they wait for prey. They can remain still for weeks.
They 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 head to pump out water during respiration. Doing so also allows them to be more unnoticeable and prevent detection from unwanted predators.
Sawback Angelshark Future and Conservation: They are uncommon and have a slow reproduction, and are critically endangered. Their minimum population doubling time is 4.5 – 14 years, and therefore have a high to very high vulnerability. They are target in commercial fisheries, demersal and bottom trawlers, as well as caught as bycatch.
Sawback Angelshark Recorded Attacks on Humans: Sawback 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.
Capapé C, Diatta Y, Seck AA, Guélorget O, Ben Souissi J, & Zaouali J (2005). ”Reproduction of the sawback angelshark Squatina aculeata (Chondrichthyes: Squatinidae) off Senegal and Tunisia”. Cybium 29: 147-157.