Nocturnally active shark with thorn-like denticles that performs diel vertical migrations
The Prickly shark (Echinorhinus cookei) is a shark in the family Echinorhinidae. It is found in the Pacific Ocean over continental and insular shelves and slopes, and in submarine canyons. It is generally bottom-dwelling and inhabits cool waters 330–3,610 feet deep, but it also frequently enters shallower water in areas such as Monterey Bay off California. Nocturnally active, the Prickly shark rests during the day in deeper offshore waters and performs a diel vertical migration to shallower inshore waters at dusk. Individual sharks have a small home range and tend to remain within a given local area. They are high suction on the RSI, and consumes a variety of bony and cartilaginous fishes, and cephalopods. They are dark in color, stalky and have dense thorn-like dermal denticles. They can grow to 13.1 feet long. Based on research, Prickly sharks produce large litters.
Family: Carcharhinidae – Requiem sharks
Common Name– Dogfish Sharks
Common Name– Bramble Sharks
Status: IUCN Red List DATA DEFICIENT
Average Size and Length: Prickly sharks are born at 1.5 feet. Mature males are anywhere from 5.9 feet to 7.5 feet in length. Females are on average 8.3 feet in length. The maximum recorded length is 13.1 feet.
Average Weight: The maximum recorded weight of a Prickly shark is 586 pounds for a 10-foot-long female.
Teeth and Jaw: The mouth of the Prickly shark forms a broad arch, with very short furrows at the corners. There are 21–25 and 20–27 tooth rows in the upper and lower jaws. The knife-like teeth each have a strongly angled main cusp flanked by up to three smaller cusplets on either side; the lateral cusplets are absent in young sharks.
Head: The Prickly shark has a short, moderately flattened head. The nostrils are placed far apart and preceded by small flaps of skin. The spiracles are tiny and positioned well behind the eyes, which lack nictitating membranes.
Denticles: The skin has a dense, uniform covering of non-overlapping dermal denticles measuring up to 0.4 cm across. Unlike the Bramble shark, they aren’t fused together. Each denticle is thorn-like, with strong ridges running down the central spine and radiating out over the star-shaped base. The denticles beneath the snout are very fine in adults.
Tail: The caudal fin of the Prickly shark has a longer upper lobe without a notch in the trailing margin, and an indistinct lower lobe. The caudal peduncle is stout does not have depressions at the caudal fin origins.
Demographic, Distribution, Habitat, Environment and Range: The Prickly shark is widely circulated around the Pacific Ocean. In the western and central Pacific, it has been reported off Japan, Taiwan, Victoria and Queensland in Australia, and New Zealand, as well as around the islands of Palau, New Caledonia, Tonga, Hawaii, and possibly the Gilberts. In the eastern Pacific, it is known to occur from Oregon to El Salvador (including the Gulf of California), around the Cocos and Galapagos Islands, and off Peru and Chile. The one place that the Prickly shark is abundant year-round is Monterey Canyon off California.
The Prickly shark prefers cool waters ranging from 41.9–51.8 °F. Their average depths are below 330–660 feet in the tropics. However, they are known to range shallow inshore waters from 36 feet down to deep depths of 3,610 feet across continental and insular shelves and slopes towards the bottom. Some researchers believe they may go as deep as 4,900 feet. In Monterey Canyon, Prickly sharks are found consistently at 49-115 feet long and Moss Landing at 13 feet deep. It can also be found inside submarine canyons, close to the walls. It prefers areas with a muddy or sandy substrate. The Prickly shark is tolerant of low dissolved oxygen levels, allowing it to inhabit oceanic basins inaccessible to other sharks.
Nocturnally active, the Prickly shark rests during the day in deeper offshore waters and performs a diel vertical migration to shallower inshore waters at dusk. Individual sharks have a small home range and tend to remain within a given local area.
Diet: Their primary diet consists of a variety of benthic and pelagic bony fishes, including hake, flounders, rockfishes, lingcod, topsmelt, mackerel, and herring, and on cartilaginous fishes, including Elephantfishes, Spiny Dogfish, young Bluntnose Sixgill sharks, and Ghost Catshark egg cases. Secondary prey items include octopuses and squid.
Adult Bluntnose Sixgill sharks may prey upon young Prickly sharks.
Ram-Suction Index: They are high on the suction side of the RSI. The size and structure of the prickly shark’s mouth and pharynx suggests that it uses suction to capture prey.
Aesthetic Identification: The Prickly shark has a cylindrical body that is a bit flabby. The adults do appear bulkier than juvenile sharks. There are five pairs of gill slits, with the fifth pair the longest. The Prickly shark is plain brown or gray, often with a purplish tint, and has black trailing margins on the fins. The underside is counter-shaded paler, most obviously on the snout and around the mouth. The lateral line runs along each side of body in a conspicuous furrow. The pectoral fins are short, while the pelvic fins are relatively large with long bases. The first dorsal fin is small and originates at or behind the level of the pelvic fin origins; the second dorsal fin is similar to the first and positioned close behind. The anal fin is absent.
Biology and Reproduction: The Prickly shark is ovoviviparous. There is only one known record of a pregnant female, which was gestating 114 embryos. This is one of the largest recorded litters of all sharks. More than likely, the young are under 16 inches long at birth. Research suggests that males reach sexual maturity around 6.6 feet and females between 8.2-9.8 feet long.
Behavioral Traits, Sensing and Intelligence: Prickly sharks have been studied extensively about their diel vertical migration patterns, and studies show active duck to nocturnal consistency as well as local vicinity. It is thought that this movement is related to feeding on schooling fish. These studied groups in Monterey Canyon also regularly form aggregations. Some numbering over 30 Prickly sharks.
Speed: The Prickly shark is a slow swimmer and has been observed hovering just above the sea floor.
Prickly Shark Future and Conservation: They have been accidently captured and are susceptible then to commercial bottom trawls, gillnets, or line gear. This is only bycatch though because there is little commercial value of the soft meat. There just isn’t enough data to evaluate them accurately.
Prickly Shark Recorded Attacks on Humans: Prickly sharks are harmless to humans. They have been innocently curious about divers.