Common
Names:
Shorttail stingray.
Latin
Name: Dasyatis brevicaudata
Family:
Dasyatidae
Identification:
Rhomboid
disc. Anterior disc margins almost
straight with rounded tips. Dorsum smooth and dark brown to dark grey with a
line of small white spots running down each side of body from level with the
eyes towards the tail. Ventrum pale. Tail (usually with two stings) tapers
quickly to a short thin whip. Tail shorter than disc with long ventral
finfold.
Size:
Maximum
disc width 2m.
Habitat:
Sand
and rocky bottoms often near rocky reefs and continental drop offs. Intertidal
to 476m. Observed mating in cave systems in New Zealand.
Abundance
and distribution: East
and South Africa, Australia, and New Zealand. Reports from Thailand
probably refer to the closely related Matsubara's Stingray (Dasyatis
matsubarai) from Japan.
Behavior:
Moves into shallow water at flood tide to feed. Feeds on bony fishes, bivalves,
squid, and crustaceans.
Reproduction:
Viviparous.
In NZ males have been observed biting and holding onto the much larger females
pectoral fin for hours at a time. During actual copulation the male flips upside
down under the female and inserts one clasper. He
then beats his pectoral fins up and down and in so doing moves his clasper in
and out of the females cloaca. During maturation males have been observed
nudging the female which may stimulate the birthing process.
Observations:
Photographs:
Roe Reef, Rottnest Island, Western Australia.
Similar
species:
Matsubara's Stingray (Dasyatis matsubarai) has a very similar appearance
including the rows of white spots, but is only known from Japan and possibly
Thailand.
Reaction
to divers: The shorttail stingray moves away when approached but may
ignore divers when concentrating on mating.
Diving
logistics: Although I have seen
Shorttail rays on almost every dive at Rottnest Island I found these big rays
very unapproachable. A far better location to try would be the Poor
Knights Marine Reserve off of New Zealand where hundreds of Shorttail stingrays
Congregate to mate each summer.
Other
diving locations submitted by readers:
References
and further reading:
Reef
Sharks and Rays of the World. Scott W. Michael. Sea Challengers.
Sharks
and Rays - Elasmobranch Guide of the World. Ralf M. Hennemann. IKAN.
