Family: Hexanchidae – Cow Sharks
Common Name– Cow and Frilled Sharks
Common Name– Cow Sharks
Status: IUCN Red List NEAR THREATENED
Average Size and Length: The Sharpnose Sevengill shark is usually between 2-3.9 feet in length, with a maximum recorded length of 4.6 feet.
Current Rare Mythical Sightings: The Sharpnose Sevengill shark goes by several other names such as the One-Finned shark, Perlon shark, Sevengill Cow shark, Sharpsnouted Sevengill shark or Slender Sevengill shark.
Teeth and Jaw: The mouth of the Sharpnose Sevengill shark is narrow and strongly curved, containing 9-11 teeth on either side of the upper jaw and five teeth on either side of the lower. The upper teeth are narrow and hook-shaped with small lateral cusps, while the lower teeth are broad and comb-shaped, except for a symmetrical symphysial tooth.
Head: It has a narrow, pointed head. The eyes are very large and fluoresce green in live specimens.
Denticles: The closely overlapping dermal denticles are very thin and transparent; each is longer than it is broad, bearing a distinct median ridge and two lateral ridges ending in marginal teeth.
Demographic, Distribution, Habitat, Environment and Range: The Sharpnose Sevengill shark can be found in the tropical and temperate regions of all oceans except for the northeastern Pacific Ocean. It is found from North Carolina to Cuba, including the northern Gulf of Mexico, and from Venezuela to Argentina in the western Atlantic. In the eastern Atlantic, it can be found from Morocco to Namibia, including the Mediterranean Sea. It is reported from the Indian Ocean off southwestern India, Aldabra Island, southern Mozambique, and South Africa. In the Pacific Ocean, it is known from Japan to China, Indonesia, Australia, New Zealand, and northern Chile.
The Sharpnose Sevengill shark is benthic, epibenthic, demersal to semipelagic. Usually found at a depth of 980–1,970 feet, but has been reported, but unconfirmed close to the surface or down to 3,300 feet. It is mainly found on the outer continental shelf and upper continental slope and may aggregate around seamounts.
Diet: The Sharpnose Sevengill shark feeds mainly on teleost’s and cephalopods. It feeds secondary on small cartilaginous fishes. In some locations, crustaceans make up some of its diet. Its feeding activity increases at night.
Larger sharks may prey upon the Sharpnose Sevengill shark.
Aesthetic Identification: The Sharpnose Sevengill shark has a slender, fusiform body. There are seven pairs of gill slits that extend onto the throat. It is brownish grey to olive above, and counter-shaded light underneath. Some individuals have dark blotches on the body or light posterior fin margins. Juveniles have dark blotches on the flank and dark tips on the dorsal fin and upper caudal lobe. A single small dorsal fin is located behind the pelvic fins, with a straight front margin, narrowly rounded tip, and concave rear margin. The pectoral fins are small with a weakly convex outer margin. The anal fin is small with nearly straight margins.
Biology and Reproduction: Known parasites of the Sharpnose Sevengill shark are nematodes and cestodes.
The Sharpnose Sevengill shark is ovoviviparous, with no apparent reproductive season. The females give birth to litters of 9–20 pups. The newborns measure about 10 inches long. Males mature at 2.46–2.79 feet long and females between 3.0–3.3 feet long. The onset of sexual maturation in males may be marked by the formation of mucus on the tips of the claspers.
Behavioral Traits, Sensing and Intelligence: The Sharpnose Sevengill shark is small, yet considered an aggressive, top predator.
Speed: The Sharpnose Sevengill shark is a strong swimmer.
Sharpnose Sevengill Shark Future and Conservation: Small to moderate numbers of Sharpnose Sevengill sharks are captured as bycatch in certain deepwater commercial fisheries on longlines or in trawls. They are used for fishmeal and liver oil; the meat is said to be of good quality, but the flesh is considered to be mildly poisonous to humans if eaten.
Sometimes kept in aquaria.
Sharpnose Sevengill Shark Recorded Attacks on Humans: The Sharpnose Sevengill shark is reasonably small and is located in generally deep water, and these characteristics classify this shark as harmless to humans. However, if captured or threatened, it will become aggressive and will defend itself.