sicklefin weasel shark
A Weasel shark with sickle-shaped fins
The Sicklefin Weasel shark (Hemigaleus microstoma) is an uncommon species of ground shark in the family Hemigaleidae. It is native to southern India, southern China, and parts of Southeast Asia, living in shallow waters down to a depth of 560 feet. The Sicklefin Weasel shark stays close to the ocean floor.
Family: Hemigaleidae – Weasel sharks
Common Name– Ground Sharks
Common Name– Weasel Sharks
Status: IUCN Red List VULNERABLE
Average Size and Length: The Sicklefin Weasel shark reaches 3.6 feet in length.
Teeth and Jaw: The mouth of the Sicklefin Weasel shark forms a very short, wide arch and conceals the teeth when closed. Moderately long furrows are present at the corners of the mouth. It has 25–34 upper and 37–43 lower tooth rows; the upper teeth are broad and angled with a smooth leading edge and strongly serrated trailing edge, while the lower teeth are narrow, erect, and smooth-edged.
Head: The snout of the Sicklefin Weasel shark is long and rounded, with the nostrils preceded by short skin flaps. The large, oval eyes are equipped with nictitating membranes and are followed by tiny spiracles.
Denticles: The dermal denticles are small and overlapping; each denticle has 5 horizontal ridges leading to marginal teeth.
Tail: The upper surface of the caudal peduncle has a crescent-shaped notch at the caudal fin origin. The asymmetrical caudal fin has a well-developed lower lobe and a long upper lobe with a ventral notch near the tip.
Demographic, Distribution, Habitat, Environment and Range: The Sicklefin Weasel shark can be found off southern India and Sri Lanka, as well as from southern China and Taiwan to Java and Borneo. There have been some reports (unconfirmed) Philippines and in the Red Sea. The Sicklefin Wesel shark inhabits continental and insular shelves from inshore waters to at least a depth of 560 feet, and usually swims close to the sea floor.
Diet: The diet of the Sicklefin Weasel shark is mostly cephalopods, though crustaceans and echinoderms may be occasionally eaten.
Ram-Suction Index: The Sicklefin Weasel shark’s small mouth and short gill slits may be adaptations for capturing cephalopods by suction. Its weak jaws and small teeth seem to suggest a diet of mostly soft-bodied prey.
Aesthetic Identification: The Sicklefin Weasel shark is slender. It is light grey or bronze above, often with small white spots on the sides, and counter-shaded pale below. The dorsal fins are tipped in white, which is especially obvious on the second dorsal as the remainder of fin is mostly dark. There are 5 pairs of short gill slits. The fins are falcate, particularly the dorsal fins, pelvic fins, and lower caudal fin lobe. The pectoral fins are narrow and pointed. The first dorsal fin is positioned about halfway between the pectoral and pelvic fins. The second dorsal fin is about two-thirds as tall as the first and is positioned slightly ahead of the anal fin. The anal fin is smaller than the second dorsal fin.
Biology and Reproduction: The Sicklefin Weasel shark is viviparous. Females produce 2 litters per year, suggesting a gestation period under 6 months. There are between 2 and 4 pups per litter. Newborns measure roughly 18 inches long. Males mature sexually around 29–30 inches long, and females mature around 30–31 inches long.
Sicklefin Weasel Shark Future and Conservation: It is caught by artisanal fishers throughout its range, mostly in drifting and bottom gillnets, but also in bottom trawls and on longlines. The meat is eaten, the fins are used in shark fin soup, and the offal is processed into fishmeal.
Sicklefin Weasel Shark Recorded Attacks on Humans: Not a threat to humans.