The red Stingray ,Dasyatis akajei (1871)

Phylum : Chordata Class : Chondrichthyes Subclass : Elasmobranchii Order : Myliobatiformes Family : Dasyatidae Genus : Dasyatis Species : D. akajei

The red stingray can grow to 2 m long and 0.66 m across, though most do not exceed 1 m in length. The maximum recorded weight is 10.7 kg. It has a diamond-shaped pectoral fin disc wider than long, with nearly straight front margins converging to a triangular snout. The small eyes are slightly elevated, and followed by spiracles that are almost twice as large. There is a thick flap of skin between the large nares. The teeth are arranged with a quincunx pattern into a pavement-like surface. Females and juveniles have blunt teeth, while adult males have pointed, recurved teeth. There is a row of 3 papillae across the floor of the mouth, sometimes with up to 2 pairs of accessory papillae alongside.

The tail is whip-like and measures 1–1.5 times as long as the disc is wide. A long, serrated spine originates in the first third of the tail, and is followed by a low dorsal keel and a ventral fin fold. Young rays have smooth skin, while adults have a patch of small dermal denticles between and behind the eyes, and a row of thorns along the midline of the back. There are 1–6 tubercles in front of the tail spine, and numerous small denticles behind. This species is plain brown above, often with yellow or orange coloring before the eyes, behind the spiracles, around the disc margin, and laterally on the tail in front of the spine. The tail darkens to nearly black towards the tip and on the ventral fin fold. The underside is white with bright orange-red patches. The Mekong freshwater stingray (D. laosensis) is also characterized by orange ventral coloration and has some similar meristic counts to this species, but differs in disc shape, denticle coverage, and dorsal coloration.

As an apex predator in nearshore demersal food webs, the red stingray plays a significant ecological role. Crustaceans are the most important component of its diet, followed by small bony fishes and then annelid worms, while molluscs are seldom consumed. In Tokyo Bay, important crustacean prey species are Crangon affinis for males, Oratosquilla ijimai for females, and Anisomysis ijimai for juveniles; the most important fish prey species is Sardinops melanostictus, followed by Conger myriaster. Like other stingrays, the red stingray is aplacental viviparous. During courtship, the male follows the female and bites at her pectoral fin disc, using his pointed teeth to gain a grip for copulation. The litter size has been variously reported as only 1 or up to 10. Males mature sexually at a disc width of 35–40 cm, and females at a disc width of 50–55 cm.