Masked Stingaree

The pectoral fin disc of the masked stingaree is approximately as long as wide, and has a rounded shape. The anterior margins of the disc are nearly straight and converge at an obtuse angle on the fleshy, non-protruding snout. The eyes are modestly sized and immediately followed by comma-shaped spiracles with angular posterior rims. The outer margin of each nostril is enlarged into a broad, flattened lobe. Between the nostrils is a skirt-shaped curtain of skin with a fringed trailing margin, that conceals the small mouth. The lower jaw bears a patch of subtle papillae (nipple-shaped structures); there are also 3–4 papillae on the floor of the month. The small teeth have roughly oval bases. The five pairs of gill slits are short. The pelvic fins are small with rounded margins. The tail measures 67–86% as long as the disc; it has an oval cross-section and is slightly flattened at the base. There is a single serrated stinging spine on the upper surface of the tail, which is immediately preceded by a rather large dorsal fin. The tail ends in an elongated, leaf-shaped caudal fin, and lacks lateral fin folds. The skin is devoid of dermal denticles. …

Found off Western Australia from Shark Bay to Geographe Bay, the masked stingaree is one of the most abundant representatives of its family within its range, particularly in the south. This bottom-dwelling ray has been reported from the shore to a depth of 115 m (377 ft) on the continental shelf, and seems to be most common in offshore waters 20–35 m (66–115 ft) deep. It favors sandy flats and seagrass beds. There is no evidence of segregation by age or sex, or of seasonal migrations.

Polychaete worms and crustaceans are the predominant sources of food for the masked stingaree; on occasion sipunculid worms, molluscs, and echinoderms are also taken. This species preys on both sedentary polychaetes, which generally inhabit deeply buried tubes, and on errant polychaetes, which are generally more mobile and shallowly buried. The expanded lobes and sensory papillae adjacent to its mouth likely aid in locating and excavating such burrowing prey. Young rays feed mainly on crustaceans, including mysids, amphipods, cumaceans, tanaids, and shrimp. With age polychaetes are added to the diet; sedentary polychaetes are significant to rays 13–29 cm (5.1–11.4 in) across, while errant polychaetes become progressively more important such as that the largest rays eat little else. Like other stingrays, the masked stingaree is aplacental viviparous. Females have a single functional uterus (the left) and produce a single pup (rarely two) per year. Ovulation and mating occur from mid-June to mid-July; fertilized eggs are enclosed by a delicate brown capsule and maintained in a state of diapause (dormancy) within the uterus until November. …