Pyjama shark

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Pyjama shark
A gray shark with barbels and prominent horizontal stripes, lying on the sandy sea bottom surrounded by sea urchins and kelp

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Carcharhiniformes
Family: Scyliorhinidae
Genus: Poroderma
Species:
P. africanum
Binomial name
Poroderma africanum
(J. F. Gmelin, 1789)
World map with blue shading along the coast of South Africa
Range of the pyjama shark
Synonyms

Squalus africanus Gmelin, 1789
Squalus striatus Forster, 1844
Squalus vittatus Shaw, 1798

The pyjama shark or striped catshark (Poroderma africanum) is a

bottom-dwelling species can be found from the intertidal zone to a depth of around 100 m (330 ft), particularly over rocky reefs and kelp beds. With a series of thick, parallel, dark stripes running along its stout body, the pyjama shark has an unmistakable appearance. It is additionally characterized by a short head and snout with a pair of slender barbels that do not reach the mouth, and two dorsal fins
that are placed far back on the body. It can grow up to a length of 1.1 m (3.6 ft) long.

The pyjama shark is primarily

oviparous, with females laying rectangular, dark brown egg cases two at a time year-round. This small and harmless shark adapts well to captivity and is commonly displayed in public aquariums. It is often caught as a bycatch of commercial and recreational fisheries. Many are killed by fishers who regard them as pests. Although there are no data suggesting its numbers have declined, the International Union for Conservation of Nature
(IUCN) has assessed the pyjama shark as least concern.

Taxonomy

The pyjama shark was originally described as Squalus africanus by German

type specimen.[2] In 1837, Scottish physician and zoologist Andrew Smith created the new genus Poroderma for this species and the related leopard catshark (P. pantherinum, at the time believed to be multiple species).[3] In 1908, the pyjama shark was made the type species of the genus by American zoologist Henry Weed Fowler.[4]

Distribution and habitat

Kelp beds are a preferred habitat of the pyjama shark.

A

inshore waters, the pyjama shark is found off South Africa, from Table Bay off Cape Town to north of East London. It is most abundant off the Western Cape, and may venture as far as Saldanha Bay in the west and KwaZulu-Natal in the east; old records from Mauritius, Madagascar, and Zaire are almost certainly erroneous.[1][5] The pyjama shark is commonly encountered in very shallow intertidal and littoral waters no more than 5 m (16 ft) deep, though in and around Algoa Bay it occurs at depths of 50–100 m (160–330 ft) and has been reported to 108 m (354 ft).[5] It favors rocky reefs and beds of Ecklonia kelp.[1][6]

Description

Profile view of a pyjama shark, from Illustrations of the Zoology of South Africa (1838).

The pyjama shark is the larger and thicker-bodied of the two Poroderma species, growing to 1.1 m (3.6 ft) long and 7.9 kg (17 lb) or more in weight. Both sexes grow to roughly the same maximum size. The head and snout are short and slightly flattened, with a narrowly parabolic outline when viewed from above or below. Each nostril is split into tiny incurrent and excurrent openings by a flap of skin in front; the flap has a three-lobed shape with the central lobe forming a long, conical barbel. The barbels are thicker than in the leopard catshark, and do not reach the mouth. The eyes are horizontally oval and placed rather high on the head, with rudimentary nictitating membranes (protective third eyelids) and a thick ridge running underneath. The sizable mouth forms a broad arch, with short furrows extending from the corners onto both the upper and lower jaws; the upper teeth are exposed when the mouth is closed. There are 18–25 and 14–24 tooth rows on either side of the upper and lower jaws, respectively. The teeth have a slender central cusp flanked by a pair of small cusplets; those of adult males are slightly thicker than those of females.[5][7]

The body is fairly compressed from side to side and tapers towards the tail. The two

albino specimen has been recorded from False Bay.[5][7]

Biology and ecology

Rather slow-swimming, the pyjama shark spends most of the day resting in caves or crevices or amongst kelp, emerging at night to actively forage for food. Many individuals may congregate at a single spot, particularly in summer.

nitrogenous wastes. Experiments have shown that the shark's capacity for osmoregulation is dependent on how well it has fed.[6]

The pyjama shark feeds on a wide variety of small animals, including

chokka squid (Loligo vulgaris reynaudi), which occur unpredictably year-round but peak from October to December, pyjama sharks deviate from their nocturnal habits and gather in substantial numbers inside the squids' "egg beds" during daytime. The sharks conceal their heads amongst the egg masses, while their stripes break up the outlines of their bodies. As the female squid descend to the sea floor to attach their eggs, guarded by the males, they become vulnerable to the sharks' ambush attacks.[6][9][16]

Close view of a brown, vase-shaped egg case cradled by feathery gorgonian branches
Female pyjama sharks lay dark brown egg capsules, which are attached to structures on the sea floor.

An

gorgonians. Eggs maintained in aquariums hatch in approximately five and a half months, with the hatching shark measuring 14–15 cm (5.5–5.9 in) long.[1][13] Males and females begin to mature sexually at 78–81 cm (31–32 in) and 79–83 cm (31–33 in) long respectively, and all sharks are adult by a length of 89 cm (35 in).[1]

Human interactions

Among the most common South African catsharks,

bottom trawls; they are also readily hooked by recreational anglers, especially during the summer when they aggregate. Although edible, most are discarded while some are used for lobster bait.[1][8] The toll taken by fishery bycatch is likely greatly underestimated, as many fishers who use line gear regard pyjama sharks as pests that "steal" bait, and kill them before discarding them.[5]

The International Union for Conservation of Nature (IUCN) has listed the pyjama shark as least concern, citing its small distribution and a recent increase in fishing pressure on small sharks in the region. However, there is no evidence to suggest that its population has declined. There are no specific conservation measures in place for this species, though its range encompasses two marine reserves. The South African Sea Fisheries Research Institute is considering legally decommercializing the pyjama shark, which would limit the degree to which it can be targeted by commercial fisheries.[1]

References

  1. ^
    doi:10.2305/IUCN.UK.2020-2.RLTS.T39348A124404008.en
    . Retrieved 19 November 2021.
  2. ^ Gmelin, J.F. (1789). Amphibia. Pisces. Caroli a Linné. Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species; cum characteribus, differentiis, synonymis, locis. Editio decimo tertia, aucta, reformata. Lipsiae. Tome I. Pars III. pp. 1033–1125.
  3. ^ Smith, A. (1837). "On the necessity for a revision of the groups included in the Linnean genus Squalus". Proceedings of the Zoological Society of London. 1837 (5): 85–86.
  4. ^ Fowler, H.W. (1908). "Notes on sharks". Proceedings of the Academy of Natural Sciences of Philadelphia. 60: 52–70.
  5. ^
    doi:10.11646/zootaxa.1229.1.1
    .
  6. ^ a b c d e Martin, R.A. Kelp Forests: Pyjama Catshark. ReefQuest Centre for Shark Research. Retrieved on May 17, 2010.
  7. ^
    ISBN 92-5-101384-5
    .
  8. ^
    ISBN 1868253945
    .
  9. ^
    S2CID 86060081
    .
  10. ^ Bester, C. Biological Profiles: Striped Catshark. Florida Museum of Natural History Ichthyology Department. Retrieved on May 17, 2010.
  11. doi:10.2989/025776191784287547
    .
  12. doi:10.11646/zootaxa.1451.1.1
    .
  13. ^
    doi:10.1080/02541858.1997.11448441
    .
  14. ISBN 978-0-691-12072-0
    .
  15. ^ a b Lechanteur, Y.A.R.G. & Griffiths, C.L. (October 2003). "Diets of common suprabenthic reef fish in False Bay, South Africa". African Zoology. 38 (2): 213–227.
  16. S2CID 85274789
    .

External links

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