African sawtail catshark

Source: Wikipedia, the free encyclopedia.

African sawtail catshark
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Carcharhiniformes
Family: Scyliorhinidae
Genus: Galeus
Species:
G. polli
Binomial name
Galeus polli
Cadenat, 1959
Range of the African sawtail catshark

The African sawtail catshark (Galeus polli) is a

caudal fin
. Its maximum known length is 46 cm (18 in).

The diet of the African sawtail catshark consists of small

fishmeal. The fisheries off Namibia, where it is most abundant, are well-managed and do not threaten its population. Given also that sharks in deeper waters are not significantly fished, the International Union for Conservation of Nature
(IUCN) has assessed this species as Vulnerable.

Taxonomy

In 1953, Belgian

zoologist Jean Cadenat to the presence of a distinct catshark species in the region. After examining more specimens from Senegal, Cadenat described the new species in a 1959 issue of the scientific journal Bulletin de l'Institut Français d'Afrique Noire (Série A) Sciences Naturelles, naming it in Poll's honor.[2]

Distribution and habitat

The African sawtail catshark is found along much of the western coast of Africa, from southern

dissolved oxygen.[3]

Description

The African sawtail catshark attains a maximum known length of 46 cm (18 in); females tend to be larger than males.[2][4] It has a slender, firm body and a slightly flattened head with a long, pointed snout. The anterior rim of each nostril bears a triangular flap of skin. The eyes are horizontally oval, equipped with rudimentary nictitating membranes (protective third eyelids), and lack strong ridges underneath. Tiny spiracles are located behind the eyes. The mouth is large, wide, and arched, with well-developed furrows at the corners. The teeth have a central cusp and 1–2 pairs of smaller lateral cusplets. There are five pairs of gill slits.[5]

The two

dermal denticles are small and overlapping, each with three-toothed crown that bears a median ridge. There is a crest of enlarged saw-like denticles along the dorsal edge of the caudal fin.[5] This species is dusky above and light below. There are typically 11 or fewer dark gray or brown saddles and/or blotches outlined in white along the back and tail. The pattern tends to fade with age, and some individuals are uniformly colored. The interior of the mouth is black.[3][4]

Biology and ecology

Small

aplacental viviparous, with females retaining eggs internally until they hatch. There is apparently no defined breeding season, and mating and birthing occur throughout the year. Adult females have two functional uteruses and produce litters of up to 12 young; litter size increases with female size. The developing embryos are initially sustained an external yolk sac, and emerge from the egg at between 2.4 and 2.8 cm (0.94 and 1.10 in) long. Pigmentation begins to develop at an embryonic length of 5 cm (2.0 in). At around 6 cm (2.4 in) long, the embryos have well-developed external gills, which largely disappear by the time they are 10 cm (3.9 in) long. Near-term fetuses weigh over twice as much as eggs, suggesting some form of secondary maternal provisioning during gestation.[2][7] The newborns measure 10–18 cm (3.9–7.1 in) long. Males and females reach sexual maturity at 30–46 cm (12–18 in) and 30–43 cm (12–17 in) long respectively.[1][4]

Human interactions

There is intensive fishing activity in the shallower portions of the African sawtail catshark's distribution, where it is

fishmeal.[1][5] Because this species is largely protected from fishing pressure in deeper water, and the Namibian fisheries operating at its center of abundance are well-regulated, the International Union for Conservation of Nature (IUCN) has listed it as Vulnerable.[1]

References

  1. ^ a b c d e Finucci, B., Derrick, D. & VanderWright, W.J. (2021). "Galeus polli". p. e.T44649A10931893.{{cite web}}: CS1 maint: multiple names: authors list (link)
  2. ^ a b c Cadenat, J. (1959). "Notes d'ichtyologie ouest-africaine. XX. Galeus polli espèce nouvelle ovovivipare de Scylliorhinidae". Bulletin de l'Institut Français d'Afrique Noire (Série A) Sciences Naturelles. 21 (1): 395–409.
  3. ^ a b c Froese, Rainer; Pauly, Daniel (eds.) (2010). "Galeus polli" in FishBase. October 2010 version.
  4. ^
    ISBN 978-0-691-12072-0
    .
  5. ^
    ISBN 92-5-101384-5. Archived from the original
    on 2016-12-16. Retrieved 2013-11-18.
  6. doi:10.11646/zootaxa.2173.1.1
    .
  7. doi:10.1016/j.icesjms.2006.04.016
    .

External links

Media related to Galeus polli at Wikimedia Commons

Retrieved from "https://en.wikipedia.org/w/index.php?title=African_sawtail_catshark&oldid=1168796444"