Latin name

Himantura uarnak

Other name

Honeycomb stingray

Identification

The anterior margin of the Reticulate whipray is curved, the triangular snout is slightly elongated and the tip protrudes beyond the edges of the disc. In juveniles, the width and length of the disc are approximately equal, the "wings" are more rounded, and the snout converges at a more obtuse angle. Behind the small eyes are the spatulae. On the ventral surface of the disc are 5 pairs of S-shaped gill slits, a mouth and thin, long nostrils. A flap of skin with a fringed lower edge runs between the nostrils. The mouth is arched with shallow furrows at the corners. There are 4-5 protuberances on the floor of the mouth. Small, blunt teeth are staggered to form a flat surface. There are 26-40 upper teeth and 27-44 lower teeth in the mouth. The whip-shaped, slender tail is 3-3.5 times as long as the disc. Skin folds on the caudal peduncle are absent. On the dorsal surface of the caudal peduncle there is a thin, serrated spike some distance from the base, which is connected by ducts to the venom gland. The average length of the spike is 63 mm in males and 55 mm in females, and the number of serrations is 92 and 73, respectively.

The dorsal surface of the disc is densely covered with tiny heart-shaped scales arranged in a broad band from the area between the eyes to the tail. This band is well developed by the time the disc reaches a width of 50 cm. With age, the density of the coating increases and a pair of large, pearl-like barbs appear in the centre of the disc. Behind the barb, the caudal peduncle is covered with spines. The lateral line is well developed on the dorsal and ventral sides of the disc. 

Features of fish fins

Dorsal spines (total): 0; Anal spines: 0.

The pectoral fins of these rays fuse with the head to form a diamond-shaped disc that is wider than it is long. The edges of the fins are rounded. The pelvic fins are rather small and triangular. 

Fish colouring

The colouration of the dorsal surface of the disc varies with geographical habitat and age. In general, the adult disc is covered with numerous dark spots scattered over a beige or yellow-brown background that darkens behind the spine. The ventral surface of the disc is pale and unmarked. The colouration of juveniles is lighter, the spots are flatter and more densely packed, there are 7 spots on the line between the spiracles, and there are also 3 rows of spots in front of the spike. 

Distribution

They are found in the tropical waters of the Indo-Pacific. They live from the east coast of South Africa to the Arabian Peninsula and further along India to Southeast Asia, including Taiwan and the Ryukyu Islands in the north and New Guinea and northern Australia in the southeast. They have reached the Mediterranean through the Suez Canal. They are only widespread in Australian waters, where they can be found from Shark Bay to Brisbane.

Habitat

Subtropical marine amphidromous species. These bottom-dwelling fish are found close to shore on sandy bottoms in lagoons and around coral reefs from the surf zone to depths of 50m and beyond. In Shark Bay, they are often found in the surf zone during the warm season and move into deeper water in the algae thickets as the cold weather sets in. Stingrays of this species can tolerate lower salinity and swim into estuaries of rivers and mangroves, although records of their presence in freshwaters of Southeast Asia may be erroneous. They prefer water temperatures of 23-26°C.

Size

The maximum registered width of the disc is 2m, the total length is 6m and the weight is 120kg.

Behavior

During the day these stingrays usually lie motionless on the bottom, sometimes burrowing into the sand. At Shark Bay, these stingrays can be found at high tide, alone or in groups in shallow water. They have a lateral line that extends to the tip of their long tails, allowing them to sense the approach of predators. Stingrays can form interspecific groups by arranging themselves radially in a 'rosette' shape, with their tails exposed as sensitive 'antennae'.

Food and feeding habits

They prey on benthic and spawning organisms including crabs, shrimps, snails, mussels, worms, jellyfish and small bony fish. In the western Indian Ocean, 2/3 of their diet consists of fish such as sardines and anchovies. Shrimp and other crustaceans are a secondary food source. In Australian waters they almost never prey on fish and feed mainly on shrimp of the Penaeidae family.

Reproduction

It is an egg-laying fish. The embryos develop in the womb and feed on egg yolk and histotrophs. There can be up to 4 newborns in a litter. Pregnancy lasts about 1 year. Off the coast of South Africa, stingrays are 28-30 cm across at birth and reach sexual maturity at a disc width of about 1 m, corresponding to an age of 4-5 years. In Australian waters, newborn rays are 21-28 cm in length and mature at a disc width of 82-84 cm. Juveniles of H. leoparda and H. undulata differ from juveniles of Himantura uarnak in size, disc shape, scale development and number of spots. These differences are more pronounced than in adults. It is likely that Shark Bay serves as a natural nursery for the reticulated whipray. Fishing

Reticulated whipray is targeted by both artisanal and commercial fisheries. In Southeast Asia and parts of the Indian Ocean, they are caught using bottom trawls, gillnets, seines and longlines. 

Relationship with a person

Traumatogenic. An extremely poisonous sting makes these rays potentially dangerous to humans. Their meat, skin and cartilage are used for human consumption. The flavour of the meat is not highly regarded. These rays are also used in Chinese medicine.