Stinging spines from two large species of stingrays. Tip of stingray spine, showing barbs. Common Stingaree, Trygonoptera testacea (Photo: Ian Banks). Bluespotted Maskray, Neotrygon kuhlii (Photo: Ian Banks).Stingrays are cartilaginous fishes that are closely related to sharks. They have a more flattened appearance than sharks, with greatly enlarged pectoral fins attached to the head in front of the gill openings, broadly forming a disc. A slender tail protrudes from the rear of the disc and may be short and lobed, or more often long and whip-like. In many species the base of the tail is armed with one or more barbed stinging spines. The stinging spines and barbs are covered by a thin layer of skin and mucus. When this is disturbed potent venom is released.
In Australian seas there are about 50 species of rays that have tails armed with spines. Of these, 21 occur in coastal waters of Queensland. Most species are found on the seabed, on sandy or muddy substrate, but a few are found higher in the water column in open waters. Rays regularly move close inshore with the rising tide to feed on yabbies, worms, small fishes and crabs. Numerous circular depressions throughout tidal flats at low tide are a tell-tale sign of the feeding activities of rays.
Most stingray stings occur as a result of swimmers or waders treading on a ray in shallow murky conditions during a rising tide. The ray is often motionless and partially buried in the bottom sediment. If trodden on, it generally thrusts the tail upward and forward in defence, sometimes forcing the spine into the foot or ankle of the victim. The spine may break free of the ray’s tail and remain embedded in the victim, particularly if penetration is deep. Numerous small backward-directed barbs along the edges of the stinging spine make its removal difficult and painful. It is recommended that sturdy footwear with ankle protection should be worn in areas likely to be frequented by stingrays. The Common Stingaree, Trygonoptera testacea, and the Bluespotted Maskray, Neotrygon kuhlii, are two common rays occurring on shallow tidal flats of eastern Queensland.
Fishers aboard commercial trawling boats often encounter rays while sorting their catches. However most stings that occur here are less serious, as the skin and mucus covering the spines has usually already been disturbed in the trawl, reducing the amount of venom entering the wound.
Divers often encounter various species of rays, some of which may reach up to 2 m in diameter. Most rays will flee if a diver approaches too closely, however large individuals in particular should be given a wide berth and no attempt should be made to grab or touch any ray. The Blotched Fantail Ray, Taeniurops meyeni, and the Cowtail Stingray, Pastinachus atrus are large and potentially dangerous species if threatened or cornered.
The Whitespotted Eagle Ray, Aetobatus ocellatus, is a pelagic species that is often observed leaping above the surface of the sea in open waters. On rare occasions it has leapt aboard boats, in the process inadvertently striking and severely injuring the occupants with its barbed spine.
Blotched Fantail Ray, Taeniurops meyeni (Photo: Ian Banks).Whitespotted Eagle Ray, Aetobatus ocellatus (Photo: Ian Banks).
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