Planketa Velveteen Spiny Shark (Proscymnodon Plunketi)

2023 Author: Molly Page | [email protected]. Last modified: 2023-11-27 22:49

The corduroy spiny shark Planketa, or White's corduroy shark, has a stocky body, sharply tapering to the head from the pectoral fins. Young and adults have different placoid scales. The body is gray-brown in color. The belly and fins are almost black. The body length of adult males is approximately 125-131 cm. It is found only in the Southwest Pacific Ocean near New Zealand, the southeastern coasts of Australia …

Description

The length from the tip of the snout to the cloaca is 65-66% of the total length of the shark. The muzzle is short, wide, reaching its greatest width at the level of the gill slits. The length of the muzzle is approximately equal to half the distance from the eye to the first branchial slit. The snout is also short. The eyes are large, yellow-green in color, oval, the length is 2 times longer than the height. The branchial slits are short and nearly vertical, in line with the pectoral fins. The intervals between the 1st and 2nd and 2nd and 3rd branchial slits are almost equal and slightly larger than between the 3rd and 4th slits, the distance between the 3rd and 4th slits, in turn, greater than the distance between 4th and 5th. The nostrils are oblique and are located at the tip of the muzzle. The mouth is wide and slightly arched. The upper lip is narrow and rough, the lower lip is smooth and wide. The lips are not fleshy.

Caudal peduncle without lateral carinae or appendages. The second dorsal fin is slightly larger than the first. Both dorsal fins have short spines. The pectoral fins are large. The pelvic fins are smaller than the dorsal ones. There is no anal fin. The lower lobe of the caudal fin is almost undeveloped. There is a well-defined concavity on the lower edge of the caudal fin. Planketa's corduroy spiny sharks have rounded pectoral fins.

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Young and adult Planket velveteen spiny sharks have different placoid scales. Immature individuals have concave placoid scales of medium size with three sharp apices. In adult sharks, the scales are larger, with three blunt tops, concave, with low longitudinal ridges, and very ribbed. Because of these differences, for a long time, juveniles were considered to belong to the species Centroscymnus waitei, and adults to the species, Centroscymnus plunketi. In individuals of any age, the scales adhere tightly to each other and cover the entire body, with the exception of the fins and the edge of the lower lip.

Teeth

The dental formula of females is 48 / 17-18 (1417 mm - the body length of the measured sample) and 23-1-24 / 17-15 in males (1197 mm). The upper teeth are pointed, resemble a triangle in shape, and have forked roots. The lower teeth have a wide base and a sharp triangular oblique apex. The lower teeth are not the same. In the upper central part of the mouth, 3-4 rows of teeth function, on the sides - 2-3, on the lower jaw only one row functions.

Color

The body of the Planketa velveteen spiny shark is gray-brown in color. The belly and fins are almost black.

The size

The body length of adult males is about 125-131 cm. Females are larger than males, they grow up to about 170 cm. Newborn sharks have a body length of about 32-36 cm.

Area

The habitat of sharks of this species is very limited. They are found only in the Southwest Pacific Ocean near New Zealand, the southeastern shores of Australia (New South Wales) and sometimes off the southern coast of Tasmania. According to some reports, Planketa velveteen sharks were caught off the coast of the South African Republic. This information has not been confirmed, but it is quite possible that the habitat of sharks of this species is wider than is now known.

Habitat

The Planketa Spiny Sharks are deep-sea bottom fish that are found on continental slopes. The characteristic depth range is 219-1550 meters, but most often they live at a depth of 550-732 m. Differentiation of depths by sex and size of individuals was noticed.

Nutrition

Sharks of this species feed on cephalopods and bony fish.

Behavior

Sharks Planket are quite active.

Social structure

Most of their life, Planket's corduroy sharks spend alone. However, cases are known when they formed small groups consisting of individuals of the same sex and approximately the same size, which can be explained by the same differentiation of depths.

Enemies

May be threatened by large predatory fish living in a similar environment.

© Paul Clerkin, Pacific Shark Research Center

Reproduction

The corduroy spiny shark Planketa is ovoviviparous.

Breeding period

There are no reliable data on the breeding season, but females with well-developed embryos were captured in July, August and December. There is also an assumption that reproduction occurs once every 2 years.

Puberty

In males, it occurs with a body length of 100 cm, in females - at least 129 cm.

Offspring

The eggs are large (about 5 mm in diameter). Cubs are born independent, their length is usually more than 30 cm. One litter can have up to 36 cubs.

Related article Giant Shark (Cetorhinus maximus)

Benefits for humans

Sharks of this species have no commercial value, but they regularly enter the nets. They are used to make fishmeal and to obtain squalene. Planketa velveteen shark liver has a high oil content (84 g oil / 100 g fresh liver), but low vitamin A content (370 IU / g oil).

Harm to humans

They are not dangerous to humans, but sharp thorns and placoid scales can cause injury.

Population

This type of shark has low resistance to external influences. The estimated minimum doubling time of the population is 4.5-14 years (Fec = 36).

Conservation status

The Planketa spiny shark is not included in the IUCN International Red List, but has a conservation status of "NT (near threatened)", which means that the species is in a state close to the status of "endangered."

Diseases and parasites

The parasites of this shark species include tapeworms and trematodes.

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