| Tiger catshark | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Carcharhiniformes |
| Family: | Pentanchidae |
| Genus: | Halaelurus |
| Species: | H. natalensis |
| Binomial name | |
| Halaelurus natalensis (Regan, 1904) | |
 | |
| Range of the tiger catshark[2] | |
| Synonyms | |
Scyllium natalenseRegan, 1904 | |
Thetiger catshark (Halaelurus natalensis) is a species ofshark belonging to thefamilyPentanchidae, the deepwater catsharks. It is found over sandy areas and nearreef peripheries offSouth Africa and perhapsMozambique, from close to shore to usually no deeper than 100 m (330 ft). Reaching a length of 50 cm (20 in), this small, slim shark has a broad, flattened head with an upturned snout tip. It can additionally be identified by its dorsal colour pattern of ten dark brown saddles on a yellowish brown background.
Bottom-dwelling and inactive, the tiger catshark feeds on a wide variety offishes andinvertebrates from on or near thesea floor. Anoviparous species, the female retains her eggs internally until theembryos are at an advanced state of development, resulting in a relatively short hatching time after laying. Between 12 and 22encapsulated eggs are produced at a time, which the female attaches to the bottom. The tiger catshark iscaught incidentally bycommercial andrecreational fishers but has no economic value. It has been listed as vulnerable by theInternational Union for Conservation of Nature (IUCN).
BritishichthyologistCharles Tate Regan described the tiger catshark in a 1904 issue of the scientific journalAnnals and Magazine of Natural History, based on two specimens presented to theBritish Museum by J. F. Queckett. He placed the species in thegenusScyllium (asynonym ofScyliorhinus) and gave it thespecific epithetnatalense, because thetype specimens were reportedly collected off theNatal coast ofSouth Africa (though there is suspicion that they were mislabelled and actually came fromAlgoa Bay).[3][4] Later authors reassigned this species to the genusHalaelurus.[5] Thelined catshark (Halaelurus lineatus) was once treated asconspecific to the tiger catshark, until it was described as a separate species in 1975.[6]
The body of the tiger catshark is slim and firm, and it grows up to 50 cm (20 in) long. The head is broad and flattened, with a distinct and upturned snout tip. The horizontally oval eyes are situated high on the head and protected by rudimentarynictitating membranes. Beneath each eye is a broad ridge, and behind is aspiracle. The medium-sized nostrils are divided by lobe-like flaps of skin on their anterior rims. The nasal flaps do not reach the large mouth, which forms a wide arch and bears short furrows around the corners. When the mouth is closed, the centre of the lower jaw falls well short of the upper, leaving the upper teeth exposed.[5] The teeth are small and 3-cusped (rarely 5-cusped), with the central cusp the longest.[6] The five pairs ofgill slits are placed higher than the level of the mouth and face somewhat upwards.[5]
Thepectoral fins are fairly large and rounded. The origin of the firstdorsal fin lies over the last third of thepelvic fin bases, while the origin of the much larger second dorsal fin lies over the rear of theanal fin. Theclaspers of adult males are moderately long and tapering,[5] though those of some individuals may be knob-shaped and spiky.[4] The anal fin is roughly equal in size to the pelvic fins, and smaller but longer-based than the second dorsal fin. The shortcaudal fin has an indistinct lower lobe and a ventral notch near the tip of the upper lobe. The skin is thick; thedermal denticles have three-pointed crowns and are widely spaced compared to other species in the genus.[5][6] Coloured yellowish brown above and cream below, this shark has a characteristic series of ten dorsal saddles from the head to the tail; each saddle is dark brown with a darker edge and a lighter middle. Unlike in the similar lined catshark, there are no spots or additional markings between the saddles.[2][4]
The tiger catshark isendemic tosouthern Africa, but the limits of its distribution are not well known. It is known to occur off theWestern andEastern Cape, South Africa, while easterly records fromKwaZulu-Natal andMozambique are uncertain due to confusion with the lined catshark. A common,bottom-dwelling inhabitant of thecontinental shelf, this shark favours sandy flats and the edges ofreefs. It is usually found from the shore to a depth of 100 m (330 ft); sharks in the eastern part of its range tend to occur in deeper water than those in the west. There are species records from as deep as 172 m (564 ft),[1] as well as a single dubious record from 355 m (1,165 ft) down on thecontinental slope. It may segregate by size, with the adults found farther from shore.[2][4]
The tiger catshark is a sluggishpredator of a diverse array ofbenthicorganisms.[4] Its diet is dominated bybony fishes andcrustaceans, and also includescephalopods,polychaete worms, smaller sharks, andscavenged fishoffal.[1][2] It has been observed at the spawning grounds of thechokka squid (Loligo vulgaris reynaudi), feeding on squid that have descended to the bottom to mate and deposit eggs.[7] Documented predators of this species include thebroadnose sevengill shark (Notorynchus cepedianus) and theragged tooth shark (Carcharias taurus).[8][9]
Reproduction in the tiger catshark isoviparous: females produce 6–11 (typically 6–9) eggs in each of their twooviducts at a time.[1] The eggs are contained in toughcapsules around 4 cm (1.6 in) long and 1.5 cm (0.59 in) across; the capsule has thick tendrils at the corners that allow it to be secured to thesea floor. The female retains the eggs internally until theembryos are substantially developed, measuring at least 4.3 cm (1.7 in) long. Thus, the eggs hatch within only one or two months of being laid, reducing the amount of time that they are exposed to predators.[4][5] Males and females begin to reachsexual maturity at lengths of 29–35 cm (11–14 in) and 30–44 cm (12–17 in) respectively.[2]
Harmless to humans,[10] the tiger catshark iscaught incidentally bybottom trawlers,recreationalanglers, and rarely squid fishers. Though edible, it is not a valued catch and is usually discarded. TheInternational Union for Conservation of Nature (IUCN) presently classifies this species as vulnerable.[1][4]
