Author: Müller and Henle, 1838
A small, unmistakable requiem shark, with a very long, flat, laterally expanded, spadelike snout, small eyes, small, smooth-edged bladelike teeth with oblique cusps, distal blades, and no cusplets, a stocky compressed body, short, broad triangular pectoral fins, the first dorsal fin well rearward on the back with its rear tip about over the pelvic midbases, the second dorsal fin much smaller than the first and with its origin well behind the anal origin, the anal fin muchlarger than the second dorsal and with a straight posterior margin and a base without long preanal ridges, and a caudal fin with its postventral margin only moderately concave, not deeply notched. It is bronzy grey above, white below, without conspicuous markings.
Body moderately stout. Head broad, greatly depressed, and trowel-shaped; snout parabolic or bell-shaped in dorsoventral view, very long, with preoral length greater than internarial space and mouth width; eyes small, without posterior notches; spiracles absent; no papillose gillrakers on internal gill openings; nostrils small, internarial space about 4 to 6 times nostril width; anterior nasal flaps very short, narrowly triangular, and not tubular; labial furrows very short to rudimentary, with uppers shorter than lowers and falling far behind eyes; teeth similar in upper and lower jaws, anteroposteriors with slender oblique cusps and distal blades but no cusplets or serrations; cusps of lower teeth not prominently protruding when mouth is closed; 25 to 33/24 to 34 rows of teeth. Interdorsal ridge absent or rudimentary; no dermal keels present on caudal peduncle; upper precaudal pit transverse and crescentic. First dorsal origin over or behind pectoral rear tips, its midbase much closer to pelvic bases than to pectorals and its free rear tip about over pelvic midbases; second dorsal fin much smaller than first, its height 1/3 of first dorsal height or less, its origin behind anal midbase; pectoral fins very broad and triangular, not falcate, pectoral length from origin to free rear tip about equal to pectoral anterior margin; pectoral origins under interspace between fourth and fifth gill slits; anal fin much larger than second dorsal, with shortpreanal ridges and a straight or slightly concave posterior margin. Colour light grey, yellowish or brownish grey above, without a colour pattern.
Indo-West Pacific: Tanzania, Pakistan India, Sri Lanka, Malaysia, Singapore, Thailand, Java, Borneo, China, Taiwan Island, Japan. Apparently absent from Australasia and Oceania.
Habitat and Biology:
A common tropical shark of continental and insular shelves close inshore, frequently in rocky areas. Often very abundant in its range and occurring in large schools. The spadenose shark is very common in the lower reaches of tropical rivers of Malaysia, Sumatra and Borneo, but it is uncertain if thespecies can live in perfectly fresh water for extended periods like Carcharhinus leucas. Unfortunately, salinity data for riverine records of this species is not available.
Viviparous, with an unusual columnar placenta. Fertilized eggs are unusually small, 1 mm in diameter and with little yolk. Developing embryos apparently derive very little of their nutriment from yolk, have no yolk in their developed yolk sacs, and establish a placental connection with the maternal uterus extremely early in their development. Thus embryos and fetuses are nourished by the mother during the entire gestation period, through the placenta and numerous long appendiculae on the umbilical cord. Litter sizevaries from 1 to 14, and size at birth between 13 and 15 cm. In Malaysian waters these sharks apparently can breed all year; females have embryos of various sizes, and maies have mature sperm throughout the year. From length frequency data collected from about 1900 individuals of this species landed in Bombay, Nair (1976) derived age classes and growth curves and estimated average sizes at ages from 1 to 5 years. His data indicates that both sexes mature between 1 and 2 years old and reach a maximum age of about 5 years for the largest known males and at least 6 for the largest females.
Eats small pelagic schooling and bottom-living bony fishes, including anchovies, codlets (Bregmacerotidae), burrowing gobies (Tripauchenidae) and Bombay ducks (Harpadontidae), as well as shrimp and cuttlefish. Harmless to people.
Maximum about 74 cm, but most individuals smaller; still larger individuals up to 120 cm have been reported but need to be verified; males maturing at 24 to 36 cm and reaching 58 cm; adult females maturing at 33 to 35 cm and reaching at least 69 cm; size at birth 12 to 15 cm, averaging about 14 cm.
Interest to Fisheries:
An abundant species in Indian and Pakistani waters, commonly taken in artisanal and commercial fisheries. Caught with hook-and-line, longlines, floating and bottom gillnets and set bottom nets, and traps. Utilized fresh for human consumption, processed into fishmeal, and used for bait for other sharks and bony fishes.
Holotype: A single specimen, Zoologisches Museum, Berlin, ISZZ 7830, 420 mm (stuffed specimen) was mentioned in Müller and Henle's initial account of this species (Plagiostomen, (1):27, 1838), making it the presumptive holotype; however, additional specimens preserved in alcohol in the Museum National d'Histoire Naturelle, Paris, were mentioned to their emended description of the species (Plagiostomen, (2):28, 1839). Springer (1964) selected one of these Paris specimens, MNHN 1123, 518 mm adult female, as a lectotype. Type Locality: "Aus Indien".