VELVET bELLY LANTERNSHARK

Taxonomy:

Phylum– Chordata

Class– Chondrichthyles

Subclass– Elasmobranchii

Order– Squaliformes

Common Name– Dogfish Sharks

Family– Etmopteridae

Common Name– Lantern Sharks

Genus– Etmopterus

Species– spinax

Status: IUCN Red List LEAST CONCERN

Average Size and Length: They are born between 12-14 cm/5-6 inches. Mature sharks have been recorded between 33-36 cm/1-1.2 feet. The maximum recorded has been 60 cm/2 feet, however it is rare to find them longer than 45 cm/1.5 feet.

Teeth and Jaw: The mouth has thin, smooth lips. The teeth in the upper and lower jaws differ. The upper teeth are small, with a narrow central cusp and usually fewer than 3 pairs of lateral cusplets. The lower teeth are much larger, with a strongly slanted, blade-like cusp at the top and interlocking bases.

Head: The snout of the Velvet Belly lanternshark is somewhat long. The eyes have a green shine, and the spiracles are somewhat small.

Denticles: There are no lines of lateral trunk dermal denticles. The snout is covered with dermal denticles. They have irregularly arranged, hooked, needle-shaped dermal denticles.

Tail: The tail is long and slender, leading to a long caudal fin with a small lower lobe and a low upper lobe with a prominent ventral notch near the tip.

Demographic, Distribution, Habitat, Environment and Range: The Velvet Belly lanternshark can be found in the east Atlantic from Iceland to Gabon in the western Mediterranean, the Azores the Canary Islands, and Cape Verde. It has also been reported off Cape Province, South Africa. They can be found on the outer continental shelve and upper slopes (possibly clay or mud) near, or well above the bottom between 230-6,562 feet. They are mostly found between 656-1,640 feet. In the Rockall Trough, it is only found at a depth of 1,640–2,461 feet. There is one report of a Velvet Belly lanternshark as shallow as 66 feet and anther report of one as deep as 8,170 feet.

Diet: They feed on crustaceans, small fish and squid. Young Velvet Belly lanternsharks feed mainly on krill and small bony fish, transitioning to squid and shrimp as they grow larger. Velvet Belly lanternsharks off Italy also eat small amounts of nematodes, polychaete worms, and other cartilaginous fishes. It has been speculated that smaller Velvet Belly lanternsharks may be too slow to catch fast-moving cephalopods.

The Velvet Belly lanternshark is also an important food of larger fishes such as other sharks and the longnose Skate.

Ram-Suction Index: The bite force exerted by the Velvet Belly lanternshark is only around 1 N.

Aesthetic Identification: The body of the Velvet Belly lanternshark is stout and somewhat long. It is brown in color dorsally and abruptly black ventrally. There is an elongated, narrow black mark above and behind the pelvic fins. There are more black marks at the sides of the tail. The gill slits are short.

The Velvet Belly lanternshark is bioluminescent, with light-emitting photophores forming a species-specific pattern over its flanks and abdomen that emit a blue-green light visible from 9.8–13.1 feet away. Varying densities of photophores are arranged in nine patches on the shark’s sides and belly, creating a pattern unique to the Velvet Belly lanternshark. Photophores are present along the lateral line, scattered beneath the head but excluding the mouth, evenly on the belly, and concentrated around the pectoral fins and beneath the caudal peduncle.

Both dorsal fins, have stout, grooved spines in front the second is much longer than the first and curved. The first dorsal fin originates behind the short and rounded pectoral fins. The second dorsal fin is about twice the area of the first dorsal fin and originates behind the pelvic fins. There is no anal fin.

Biology and Reproduction: The Velvet Belly lanternshark is ovoviviparous having between 6-20 pups per litter. Research suggests that birth every 3 years. Ovulation typically occurs in early autumn, fertilization in the summer (or possibly in the winter if females are capable of storing sperm), and parturition in late winter or early spring. The gestation period is under one year.

The Velvet Belly lanternshark’s bioluminescence develops before birth; the yolk sac is fluorescent before any photophores have formed, suggesting the mother transfers luminescent materials to her offspring. The first luminous tissue appears when the embryo is 2.2 inches long, and the complete pattern is laid down by the time it is 3.7 inches long. At birth, the young shark is already capable of counter-illumination with 80% of its ventral surface luminescent. (Claes, J.M. & Mallefet, J. (2008). “Early development of bioluminescence suggests camouflage by counter-illumination in the velvet belly lantern shark Etmopterus spinax (Squaloidea: Etmopteridae)“. Journal of Fish Biology. 73 (6): 1337–1350.)

Males mature sexually between 11–13 inches long and females between 13–14 inches long. The average age at maturity is 4 years for males and 4.7 years for females, though four-year-old mature individuals of both sexes have been caught in the wild, along with immature females over eight years old. Males and females 8 and 11 years old have been caught in the wild. Research suggests that the potential lifespan of the Velvet Belly lanternshark is estimated at 18 years for males and 22 years for females.

The Velvet Belly lanternshark exhibits a number of adaptations to living in the deep sea, such as specialized T-cells and liver proteins for dealing with the higher concentrations of heavy metals found there such as cadmium, copper, mercury, or zinc found in the bloodstream. The Velvet Belly lanternshark’s liver accounts for 17% of its body mass, three-quarters of which is oil, making it nearly neutrally buoyant.

Velvet Belly laternsharks are known to have an abundance of parasites. The Anelasma squalicola barnacle is typically attached near the fin spine and deep into the muscle tissue. Known internal parasites include the monogenean Squalonchocotyle spinacis, the tapeworms Aporhynchus norvegicus, Lacistorhynchus tenuis, and Phyllobothrium squali, and the nematodes Anisakis simplex and Hysterothylacium aduncum. Some of these parasites use the Velvet Belly lanternshark’s prey as intermediate hosts and are acquired through ingestion, while others use the shark itself as an intermediate host.

Behavioral Traits, Sensing and Intelligence: The bioluminescent ventral photophores are thought to function in counter-illumination and the bioluminescent flank markings may play a role in intraspecific communication.

There is evidence that individuals also move into deeper water as they age.

They have also been found in small shoals. In some areas, females may outnumber males.

Speed: The Velvet Belly lanternshark is a slow-moving shark. It is designed to remain neutrally buoyant.

Velvet Belly Lanternshark Future and Conservation: They are quite common and are of least concern. They are caught as bycatch by bottom trawlers and pelagic trawlers. They are of little commercial value, though they have been utilized for fishmeal or food. They are stable, though the one concern is their slow reproductive rates. There is some protection in the Mediterranean from a 2005 ban on bottom trawling below 1,000 m/3,300 feet. However, in the northeastern Atlantic it has been assessed as Near Threatened, as its numbers have declined by almost 20% from 1970 to 1998–2004.

Velvet Belly Lanternshark Recorded Attacks on Humans: Not a threat to humans.