Pink Whipray

The pectoral fin disc of the pink whipray is diamond-shaped and thick at the center, measuring about 1.1–1.2 times wider than long. The outer corners of the disc are angular. The snout forms a very obtuse angle, with the tip barely protruding. The small, widely spaced eyes are followed by larger spiracles. There is a short and broad curtain of skin with a finely fringed posterior margin between the long, thin nostrils. The mouth is fairly small and surrounded by prominent furrows; the lower jaw has a small indentation in the middle. There are two large central and two tiny lateral papillae on the floor of the mouth. The teeth are small and arranged into pavement-like surfaces. Five pairs of gill slits are located beneath the disc. The pelvic fins are small and narrow. The tail is extremely long and thin, measuring at least twice the disc length when intact. It lacks fin folds and usually bears a single serrated stinging spine. Adults have small, rounded dermal denticles covering the central dorsal surface of the disc, beginning in front of the eyes and extending to cover the entire tail; there are also small, sharp thorns on the midline, which become densest at the base of the tail. Juveniles are either smooth-skinned or have a sparser covering of flat, heart-shaped denticles. …

The exact range of the pink whipray is unclear due to confusion with the Jenkins' whipray (H. jenkinsii). It is believed to be common throughout the tropical waters of the Indo-Pacific, probably occurring all around Indian Ocean periphery from South Africa to northern Australia, from the year 2014 appears in the Red Sea. Its range extends to the Pacific Ocean, northward to the Philippines, the Ryukyu Islands, and Iriomote, and eastward to various islands including Micronesia, the Marquesas Islands, and Samoa. The pink whipray has been recorded from as deep as 200 m (660 ft), but is usually found from the intertidal zone to a depth of 70 m (230 ft). This bottom-dwelling species prefers sandy flats, lagoons, and other soft-bottomed habitats, often near cays and atolls in coral reefs. It tends to be found closer to shore during the warm season. Genetic and telemetry studies across Polynesian islands have found that individual rays tend to remain within a local area, with very little between-island movement.

Small to large gatherings of pink whiprays have been observed over sandy flats and coral reefs in Shark Bay, on the Great Barrier Reef, and in the Caroline Islands. When resting, up to ten individuals may pile atop one another, sometimes mixing with other species. On Ningaloo Reef, it has been seen "riding" on larger species of rays. The pink whipray feeds primarily on decapod crustaceans, but also takes cephalopods, and teleost fishes. In Shark Bay, penaeid prawns are by far the dominant prey type for rays of all sizes. At Rangiroa Atoll in French Polynesia, sizable feeding aggregations are known to form at night in shallow water. However, at Moorea it tends to be a solitary forager with a large home range. Like other stingrays, the pink whipray is aplacental viviparous, with the mother supplying her developing embryos with nutrient-rich histotroph ("uterine milk") through specialized uterine structures. The newborns measure 55–60 cm (22–24 in) across. Shark Bay may be a nursery area for this species. Males reach sexual maturity at 1.1–1.2 m (3.6–3.9 ft) across, while the maturation size for females is unknown. Known parasites of the pink whipray include the monogeneans Heterocotyle capricornensis, Monocotyle helicophallus, M. spiremae, M. …