Velvet Belly Lanternshark

Velvet belly lanternshark is a species of deepwater sharks belonging to the family Etmopteridae. They belong to he order of dogfish sharks most commonly found in the northeastern Atlantic Ocean.

These sharks get their common name due to a dark velvet patch on their ventral surface, which differs from their general body color. Carl Linnaeus, Swedish botanist, and the father of taxonomy, was the first person to describe these sharks in 1758 in his 10th edition of Systema Naturae.

Velvet Belly Lanternshark Scientific Classification

Kingdom Animalia
Phylum Chordata
Class Chondrichthyes
Order Squaliformes
Family Triakidae
Genus Etmopterus
Scientific Name Etmopterus spinax

Description

Females of this species of sharks are bigger than the males. The average size of a mature velvet belly lanternshark is 1-1.2 feet. The biggest specimen ever recorded measured 2 feet in total body length. That said, to spot a lanternshark longer than 1.5 feet is scarce.

They have a brown-colored upper body which transitions into a blackish hue on their underside. Thin black marks are located above and behind the pelvic fins and along the surface of the caudal fin. The sides of the lanternshark, along with its velvet, pouch-like belly, consist of numerous photophores arranged in nine patches, emitting a blue-green light visible from quite a distance. The photophores are present all along the ventral part of the lateral line.

They have a long and flattened snout covered with dermal denticles, which are sharp, hooked, and haphazardly scattered. Their large eyes display a greenish shine and behind them are present small spiracles.

The mouth of this shark consists of thin and smooth upper lips. The upper jaw has small teeth of a single central cusp flanked by less than three pairs of lateral cusplets. The lower teeth are slanted with singular, narrow, sharp cusps at their tops and interlocked bases and are comparatively much larger.

They have five pairs of small gill slits about the same size as the spiracles. While the second dorsal fin (which originates behind the pelvic fins) is twice as long and curved as the first (which forms behind the short pectoral fins), both bear strong spines at the front. These sharks do not possess an anal fin but have a slender-looking tail which leads to a tall caudal fin. The caudal fin consists of a low upper lobe with a distinct ventral notch at the tip and a small lower lobe.

Where do they live

The eastern Atlantic Ocean is the natural home of these sharks, where its numbers are found across a wide range of habitation. They are found in Iceland and Norway in the North, the Mediterranean Sea, the Azores, the Canary Islands, and Cape Verde. It is also spotted  in Gabon and Cape Province on the western and southern coast of Africa, respectively.

They prefer continental and insular shelves, which are close to or located at the center of water columns. They generally live in waters of great depths ranging from 660-1640 ft. These fishes have been spotted in shallow waters having a depth of 66 ft. to deep oceanic waters of 8170 ft.

Behavior

Dietary

The velvet belly lanternsharks have a general diet and feed on various prey. Their diet consists of cephalopods such as squids, crustaceans like shrimps and krills, and bony fishes like barracudinas, pouts, and lanternfishes. Sharks living near Italian shores have also been known to feed on cartilaginous fishes, nematodes, and polychaete worms.

These sharks develop a taste for a wide variety of prey when they start maturing and growing in size.

Reproductory

Velvet belly lanternsharks follow an ovoviviparous mode of reproduction.

The bioluminescence factor of these sharks begins right from the yolk sac. Even when no photophores have developed in the embryo, the egg sac is fluorescent in appearance, suggesting that the mother provides the necessary materials her offspring needs to have a luminescent body. By the time the embryo is 2.2 inches long, the first luminous tissue appears; by the time they are 3.7 inches long, the pattern is complete. At the time of birth, a significant part of a pup’s underside is capable of being luminescent.

Ovulation begins in early autumn, while mating and egg fertilization occur in summer. The females give birth every three years, from late winter to spring, with each litter size containing 6-20 pups. Females are pregnant for about under a year.

Males reach sexual maturity at four, with a body length of 11-13 inches. Females become sexually mature at 4.7 years when they are 13–14 inches long.

The lifespan of these lanternsharks varies, with the males estimated to live up to 18 years and females capable of surviving to 22 years.

Adaptations

The velvet belly lanternshark has a contaminated bloodstream highly concetrated with metals such as cadmium, copper, mercury, or zinc. These metals come from the indigestion of fishes in the deep sea. To deal with this, these sharks have specialized T-cells and liver proteins to help them eliminate the toxic metals.

Another adaptation is its liver which takes up about 17% of its body mass and is filled three-quarters with oil, making the buoyancy levels of these sharks nearly balanced.

Interactions with humans

These small sharks are harmless to humans. Their numbers are incidentally caught as bycatch in nets set for capturing other marine animals of more excellent commercial value. Except for some instances where they are dried, salted, and used for fishmeal, these sharks are invariably killed off.

Although its numbers are still stable in its natural habitat range, the IUCN has listed the sharks as a ”Vulnerable” species due to the constant threats of overfishing and its low reproductive rate. From 1970 to 1998–2004, its numbers have seen a 20% decline.

Sources

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