| Bluegrey carpetshark | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Orectolobiformes |
| Family: | Brachaeluridae |
| Genus: | Brachaelurus |
| Species: | B. colcloughi |
| Binomial name | |
| Brachaelurus colcloughi (J. D. Ogilby, 1908) | |
 | |
| Range of the bluegrey carpetshark | |
| Synonyms | |
Heteroscyllium colcloughiJ. D. Ogilby, 1908 | |
Thebluegrey carpetshark (Brachaelurus colcloughi) orColclough's shark, is an uncommonspecies ofcarpet sharkendemic to shallow inshore waters off northeasternAustralia. It is one of the two extant members of thefamilyBrachaeluridae. The bluegrey carpetshark has a stocky body with a wide, slightly flattened head, dorsally placed eyes, and a pair of long barbels with posterior skin flaps. It has largepectoral fins, twodorsal fins of unequal size placed far back on the body, and a sizeable space between theanal fin and the base of thecaudal fin. Growing to 76 cm (30 in) long, this species has a black-and-white colour pattern as a juvenile, which largely fades with age such as that adults are brownish.
When removed from the water, the bluegrey carpetshark will close its eyes like the relatedblind shark (Brachaelurus waddi). It feeds onbenthicinvertebrates andbony fishes, and isaplacental viviparous with females bearing litters of 6–7 pups. TheInternational Union for Conservation of Nature (IUCN) has assessed this species asVulnerable, given its rarity and restricted occurrence in heavily utilized waters. It is taken in small numbers bycommercial andrecreational fisheries, and for theaquarium trade.
The bluegrey carpetshark was described by AustralianichthyologistJames Douglas Ogilby as a species ofBrachaelurus, in a 1908 issue ofProceedings of theRoyal Society of Queensland. He named the shark after his friend John Colclough, and based his account on two immature males about 46 cm (18 in) long fromMoreton Bay inQueensland, one of which was later "accidentally destroyed".[2][3]
In 1940,Gilbert Percy Whitley published the first illustrations of the bluegrey carpetshark, but unfortunately they were inaccurate in some respects, particularly on omitting a midline groove on the chin. Much taxonomic confusion then resulted, on whether the bluegrey carpetshark and the blind shark belonged to separate genera or even constituted separate species, that were not resolved until theQueensland Museum obtained new specimens for study.[3] Other common names for this species include blue-grey catshark, bluegrey shark, and southern blind shark.[4] The genus Heteroscyllium is a synonym of Brachaelurus.[5]
Rare to uncommon, the bluegrey carpetshark occurs along the northeastern coast ofAustralia fromGladstone, Queensland toBallina, New South Wales, with most records coming fromMoreton Bay. There are also a handful of reports from off theCape York Peninsula, and this species may be more widely distributed on theGreat Barrier Reef.[3][6]Demersal in nature, the bluegrey carpet shark is usually found close to shore in water less than 6 m (240 in) deep, though it has been recorded as far down as 100 m (330 ft).[6] It inhabits soft-bottomed habitats and has also been reported aroundshipwrecks.[3]
The bluegrey carpetshark has a stout body with a long, slightly flattened head. The snout is blunt and looks wedge-shaped from the side. The large eyes are horizontally oval and placed high on the head, each with a strong ridge underneath and a large, roundspiracles following immediately behind and below. Thenostrils are preceded by a pair of long barbels, which have an enlarged posterior flap halfway along their lengths. There are well-developed skin flaps and grooves around the incurrent nostril opening, as well as a pair of grooves connecting them to the small, almost transverse mouth. The tooth rows number 32–34 in the upper jaw and 21–29 in the lower jaw; each tooth has an upright, awl-like central cusp and two lateral cusplets. The five pairs ofgill slits are short, with the fourth and fifth pairs more closely spaced than the others.[3][6]
Thepectoral andpelvic fins are broad and rounded, with the former larger than the latter. The twodorsal fin have rounded apices and are placed far back, with the first originating over the pelvic fin bases. The second dorsal fin is noticeably smaller than the first. Theanal fin is less than half the size of the first dorsal fin and placed so that its free rear tip just reaches the base of thecaudal fin. The caudal fin is long and low and comprises about a quarter of the total length, with no lower lobe and a strong ventral notch near the tip of the upper lobe. Thedermal denticles are tiny, smooth, and non-overlapping. Adults are grayish to golden brown above and white below, with faint darker saddles and white patches on the dorsal fins. Juveniles have a striking pattern of large black markings on a white background.[3][6] This species can grow up to 76 cm (30 in) long.[4]
Like the blind shark, the bluegrey carpetshark shuts its lowereyelids when taken out of the water.[3] It feeds on smallbenthicinvertebrates andbony fishes.[3][6] This species isaplacental viviparous, with the unborn young losing theiregg cases early in development and being sustained byyolk sacs. Females bear litters of 6–7 young; the newborns measure around 17–18 cm (6.7–7.1 in) long.[3]
Harmless to humans, the bluegrey carpetshark is occasionallycaptured incidentally bycommercial fisheries or hooked byrecreational anglers. Small numbers are collected for theprivate aquarium trade, as it is attractive (especially young sharks) and probably adapts well to captivity.[3] TheInternational Union for Conservation of Nature has assessed this species asVulnerable, citing its narrow habitat preferences, limited range in a heavily populated region, and apparent rarity.[1]
