Author: Bleeker, 1852
A small slender shark with a rounded, moderately long snout, large lateral eyes with nictitating eyelids, small spiracles, short gill slits about 1.3 times eye length in adults (less in young), very short, small arched mouth with teeth not protruding, upper teeth with distal cusplets but no serrations, lower teeth shaped like inverted Ys, with short, straight, smooth-edgedcusps, no cusplets, and highly arched roots, highly falcate fins, including two spineless dorsal fins and an anal fin, second dorsal about 2/3 size of first, second dorsal origin slightly ahead of anal origin, anal fin smaller than second dorsal and without preanal ridges, transverse, crescentic precaudal pits, and light grey or bronze colour with no prominent markings other than white or black fin tips and sometimes white spots on sides.
Snout rounded in dorsoventral view; gill slits short, 0.8 to 1.3 times eye length in adults; mouth broadly arched and very short, its length 31 to 43% of its width; lower jaw rounded at symphysis; ends of upper labial furrows extend in front of rear corners of eyes; no toothless space at midlines of jaws; upper anterolateral teeth with smooth mesial edges and very short cusps; lower anterolateral teeth with short, slender, unhooked cusps, and no cusplets; lower crown feet and roots deeply arched, giving teeth an inverted Y shape; lower teeth not protruding when mouth is closed; tooth row counts 25 to 34/37 to 43, 6 to 20 more lower rows than uppers; dorsal and pelvic fins and ventral caudal lobe strongly falcate; second dorsal height 3/5 or more of first dorsal height.
Indo-West Pacific: Southern India, Sri Lanka, Thailand, Singapore, Java, China (including Taiwan Island), the Philippines, Australia (Queensland, northern and Western Australia).
Habitat and Biology:
This is a small, relatively common inshore species of tropical continental seas. In Australian waters the sicklefin weasel shark has been taken at depths of 12 to 167 m on the continental shelf on or near the bottom (bottom temperature 22° to 27.6°C).
Viviparous, with a yolk-sac placenta; litters from the Australian representative of the species range from 4 to 14 fetuses. Full-term fetuses with detached umbilical cords and placentae are 23.7 to 25.6 mm.
The sicklefin weasel shark is a specialist feederon cephalopods, eating mostly octopi, cuttlefish, and squid, but also crustaceans and echinoderms.
Maximum at least 91 cm, in non-Australian sharks, with mature males from 72 to 91 cm, and adult females 85 cm. In the Australian representative of the species males mature at about 60 cm and reach 94 cm; females are adolescent or subadult and possibly sexually active between 45 and 60 cm while pregnant females are as small as 68 cm, with all females above 75 cm and up to 97.2 cm being pregnant or spent. Size at birth about 26 to 28 cm. A length-weight power curve for the Australian representatives of this species (Stevens and Cuthbert, 1983) is:
WT = 2.647 x 10 -3 TL 3.07.
Interest to Fisheries:
Taken regularly in inshore artisanal fisheries in the Indo-Pacific, but apparently not extremely abundant. Caught in gillnets and probably on line gear; meat utilized for human consumption.
Syntypes: Two specimens, 625 and 701 mm females, are mentioned in Bleeker's (1852) original description. One of these is a specimen in the British Museum (Natural History), BMNH 1818.104.22.168, 703 mm female, but the other may be lost (Dr M. Boeseman, pers. comm.). Type Locality: Batavia (Djakarta), Java.