| Pygmy ribbontail catshark | |
|---|---|
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Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Carcharhiniformes |
| Family: | Proscylliidae |
| Genus: | Eridacnis |
| Species: | E. radcliffei |
| Binomial name | |
| Eridacnis radcliffei H. M. Smith, 1913 | |
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| Range of the pygmy ribbontail catshark | |
| Synonyms | |
Proscyllium alcockiMisra, 1950 | |
Thepygmy ribbontail catshark (Eridacnis radcliffei) is aspecies offinback catshark,familyProscylliidae, distributed patchily in the westernIndo-Pacific fromTanzania to thePhilippines. It occurs around the edges ofcontinental and insular shelves at a depth of 71–766 m (233–2,513 ft), typically on or near mud bottoms. One of the smallest living shark species, the pygmy ribbontail catshark grows to a maximum known length of 24 cm (9.4 in). It has a slender body with a low, ribbon-liketail fin, and is dark brown in color with blackish dorsal fin markings and tail bands. This shark feeds mainly onbony fishes, followed bycrustaceans and thensquid. It isaplacental viviparous with females bearing litters of 1–2 relatively large pups. It is of minimal significance tofisheries, being caught asbycatch in some areas.
The first known specimens of the pygmy ribbontail catshark were collected during the 1907–1910 Philippine Expedition of theU.S. Fish CommissionSteamerAlbatross.Hugh McCormick Smith, Deputy Fish Commissioner and director of the expedition, published a description of this shark in a 1913 issue of theProceedings of the United States National Museum, naming it for the expedition's General Assistant and NaturalistLewis Radcliffe, and creating for it the newgenusEridacnis.[2] Thetype specimen is a 23 cm (9.1 in) long adult female caught offJolo Island in theSulu Archipelago,Philippines.[3]
By far the most widely (if sporadically) distributed member of its genus, the pygmy ribbontail catshark has been reported fromTanzania, theGulf of Aden, theGulf of Mannar, theBay of Bengal, theAndaman Islands,Vietnam, and thePhilippines. Thisbottom-dwelling shark occurs at depths of 71–766 m (233–2,513 ft) on outercontinental and insular shelves or upper slopes, commonly over mud.[3]
The pygmy ribbontail catshark has a thin body with a short, rounded snout and elongated, oval eyes bearing rudimentarynictitating membranes. Each nostril is preceded by a short, triangular flap of skin. The mouth is wide and V-shaped, without furrows at the corners and containing numerous rows of small, multi-pointed teeth that become more comb-like towards the sides. There arepapillae on the roof of the mouth and the edges of thegill arches. The twodorsal fins are of comparable size, the first positioned slightly closer to thepectoral than thepelvic fins and the second over theanal fin. Thecaudal fin is low and long, comprising a quarter of the total length or more, and lacks a lower lobe. The coloration is a plain dark brown, with black markings on the dorsal fins and darker bands on the caudal fin. The maximum recorded lengths are 23 cm (9.1 in) for a male and 24 cm (9.4 in) for a female.[3][4] One male shark 18.6 cm (7.3 in) long weighed 14 g (0.49 oz), and a pregnant female 24.2 cm (9.5 in) long weighed 37 g (1.3 oz).[5]
The pygmy ribbontail catshark is reportedly very abundant in some places, such as off southernIndia and the Philippines.[3] One study in Indian waters found that 55% of this shark's diet was composed ofbony fishes (mainlylanternfishes but alsobristlemouths and smalleels), 28% ofcrustaceans (mainlyshrimp but alsostomatopods andcrablarvae), 14% ofsquid, and the remainder of other items including abivalve.[6]
Reproduction isaplacental viviparous, with the developing young being sustained by ayolk sac until they are ready to be born. Female pygmy ribbontail catsharks are capable of becoming pregnant at 16.6 cm (6.5 in) long, though only females over 18 cm (7.1 in) long have been found with fully developedfetuses, suggesting that they grow substantially during thegestation period. One or two pups are born at a time; the newborns are extremely large relative to their mothers, measuring around 11 cm (4.3 in) in length.[3][7] Males reachsexual maturity at a length of 18–19 cm (7.1–7.5 in) and females at perhaps 15–16 cm (5.9–6.3 in).[4] This is comparable to the sizes at maturity of thespined pygmy shark (Squaliolus laticaudus) and thedwarf lanternshark (Etmopterus perryi), ranking the pygmy ribbontail catshark among the world's smallest sharks.[8] Due to the difficulties involved in assessing reproductive maturity in sharks, whether one of these species is truly smaller than the others cannot yet be definitively determined.[8]
Pygmy ribbontail catsharks are captured incidentally inbottom trawls off the Philippines, but are not known to be utilized. Its conservation status has not been evaluated by theInternational Union for Conservation of Nature (IUCN).[3]
