SAND DEVIL OR ATLANTIC ANGEL SHARK
The devil or the angel of Florida waters
The Sand Devil or Atlantic Angel shark (Squatina dumeril) is a species of shark belonging to the family Squatinidae. They can be found in the northwestern Atlantic Ocean, off the coast of the eastern United States, including right here in Florida, in the northern Gulf of Mexico, and possibly in parts of the Caribbean Sea. This bottom-dwelling shark is found in shallow inshore waters in summer and fall, and most likely deep offshore waters in winter and spring.
Family: Squatinidae – Angel Sharks
Common Name– Angel Sharks or Angelsharks
Status: IUCN Red List DATA DEFICIENT
Average Size and Length: Mature males have been measured between 92- 107 cm/ 3-3.5 feet. The maximum recorded is 152 cm/ 5 feet.
Average Weight: They weigh at least 35 pounds.
Current Rare Mythical Sightings: French naturalist Charles Alexandre Lesueur described the sand devil in an 1818 volume of Journal of the Academy of Natural Sciences of Philadelphia. Previously, it had been regarded as the same species as the European Squatina squatina. Lesueur based his account on the holotype adult male 3.9 feet long caught off the eastern United States and named the species in honor of André Marie Constant Duméril.
Phylogenetic analysis, based on mitochondrial DNA, has concluded that the Sand Devil and the Pacific Angelshark (S. californica) are sister species. The two of them in turn form a clade with other angel sharks found in the Americas. Molecular clock estimation has timed the divergence of both at c. 6.1 Ma, around the time that the Isthmus of Panama formed. The rise of the Isthmus likely split the ancestral angel shark population, leading to their becoming separate species. See the Pacific Angelshark link here for more, and references.
Teeth and Jaw: The wide mouth is positioned terminally on the head. The jaws contain 3 rows of 20 teeth on top and 18 on the bottom. The teeth are conical with broad bases and smooth edges. They are single pointed cusps.
Head: There are tapering nasal barbels that are weakly fringed or smooth anterior nasal flaps. The lateral head folds are low with no triangular lobes. The area between the eyes is strongly concave. The large eyes are placed on top of the head and have prominent spiracles behind. The eye-spiracle space is less than 1.5 times the eye length. There are five pairs of gill slits located on the sides of the head.
Denticles: There are a few discrete small thorns that are prominent on the snout, between the eyes and on the spiracles in young, maybe in clusters of 5 or 6. There are more numerous and forming patches in adults. The thorns along the back of young are reduced and inconspicuous in adults. The dermal denticles have rounded bases and three horizontal ridges. There is a distinctive band of larger thorns running along the midline of the back, from the nape to the caudal peduncle.
Tail: The lower lobe of the caudal fin is larger than the upper lobe.
Demographic, Distribution, Habitat, Environment and Range: Sand Devils or Atlantic Angel sharks can be found in the northwest Atlantic from New England to the Gulf of Mexico. There are unconfirmed sightings in Cuba, Nicaragua, Jamaica, and Venezuela. It is quite common from Massachusetts to the Florida Keys. They can be found over the continental shelf and the slope, on or near the bottom; on sandy bottoms or muddy bottoms. They are close inshore to 4,232 feet, but mostly between 131-820 feet. They will appear inshore in shallow water in spring and summer off the USA and they disappear in the winter, probably to deeper water.
The Sand Devil feeds both during the day and at night. It tends to select prey approximately 50–60% as long as its mouth is wide which yields the most efficient rate or energy return. The variety of prey taken is greatest in fall and least in winter, and smaller sharks have a more varied diet than larger ones.
Larger species of fish and marine mammals are potential predators of the Sand Devil or Atlantic Angel shark.
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. The shark presses the forward lobes of its pectoral fins against the bottom and thrusts its head upwards at up to a 90° angle. Its mouth forms a tube when opened, creating a suction force, while its jaws protrude forward to secure the prey between sharp teeth. During the strike, the eyes roll backward into the head for protection. The strike is often completed in under a tenth of a second.
Aesthetic Identification: The San Devil or Atlantic Angel shark is plain bluish to an ashy grey in color. There are no elaborate markings or ocelli. There are dusky or blackish spots irregularly present, or not there at all. The young typically have small white spots. The underside of the Sand Devil is white with red spots and reddish fin margins. The dorsal and caudal fins are darker with light bases. The dorsal rear tips are light. It has a flattened body, much like that of a skate or of a ray, except longer. It has enlarged pelvic and pectoral fins. The pectoral fins are broad and posteriorly angular with narrow rear tips. The front of the pectoral fins is broad and angular with narrow rear tips. The front of the pectoral fins is separate from the head, this is what forms the triangular lobe. The two dorsal fins are similar in size and shape and are positioned far back on the body. The anal fin is absent.
Biology and Reproduction: They are ovoviviparous having up to 25 pups per litter. Mating occurs in the spring; adult males have spines on the outer margins of their pectoral fins, which may help in gripping the female during copulation. Females reproduce no more than once every two years, perhaps longer. They are born in the summer, after a gestation period thought to be around 12 months. Birthing occurs between February and June at depths of 66–98 feet. The newborns measure 9.8–11.8 inches in length. Males and females sexually mature at around 37 and 34 inches long.
Behavioral Traits, Sensing and Intelligence: The Sand Devil is an ambush predator that spends much time buried in the bottom sediment. They lie buried still in the mud or in the sand during the day waiting to ambush prey. They are actively swimming during the 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.
The Sand Devil has 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.
Sand Devil or Atlantic Angel Shark Recorded Attacks on Humans: Sand Devils 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.