Pelagic Stingray
The Pelagic Stingray, (Pteroplatytrygon violacea), is a species of stingray in the family Dasyatidae, and the sole member of its genus. The adult specimens can reach 160 cm in length (including the tail) and 80 cm in width. It is characterized by a very tapered discoidal body with large pectoral fins. The eyes, unlike of the other stingrays, are not protruding. Distributed in temperate and subtropical waters around the world; you discover it all over the Mediterranean Sea. It prefers a pelagic habitat, off the continental shelf and far from the seabed. trigone viola
In adopting a midwater lifestyle, the pelagic stingray exhibits several characteristics different from those of its bottom-dwelling relatives. While most stingrays propel themselves by undulating their disc margins, this species swims by oscillating (flapping) its pectoral fins in a manner approaching the “underwater flying” employed by eagle rays. Oscillatory fin motions generate lift, thus improving cruising efficiency in open water at a cost to maneuverability. The pelagic stingray is adept at swimming backwards, which may compensate for the lower fine control offered by its swimming mode. Vision seems to be more important to the pelagic ray in finding food than in other stingrays. Compared to other members of its family, this species has less than one-third the density of electroreceptive ampullae of Lorenzini on its underside. The ampullae also cover a smaller area, though not as small as in eagle rays, and are more evenly distributed between the ventral and dorsal surfaces. The lateral line of the pelagic stingray, a complex system of mechanoreceptors that detect nearby movement and ocean currents, remains similar to other stingrays in covering a greater area on the ventral than the dorsal surface. However, this species is less responsive to mechanical than to visual stimuli,
The diet of the pelagic stingray consists of free-swimming invertebrates and bony fishes. It is an active hunter, using its pectoral fins to trap and move food to its mouth, and has been known to take advantage of seasonal feeding opportunities such as spawning squid. Like other stingrays, it is aplacental viviparous, meaning that the embryos are sustained initially by yolk and later by histotroph (“uterine milk”). With a short gestation period of 2–4 months, females may bear two litters of 4–13 pups per year. Birthing generally occurs in warm water near the equator. Rarely encountered except by fishery workers, the pelagic stingray can inflict a severe, even fatal wound with its tail spine.
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