THE STEINHART AQUARIUM - Gulf of Guinea Science ...

along the coast in estuaries, bays, and over the
continental shelf.
Appearance: Flat, diamond-shaped body with
long, pointed snout; lacks the prominent notch
on the rear edge of their pectoral fins common
to all other Pacific Coast skates. Color: ranges
from brown, gray, olive, and muddy black.
Large eyespots, one on each upper pectoral fin,
as well as bright dots and mottlings. Average
length: 1.3 m; largest known: 2.4 m.
Diet: Benthic shrimps, worms, clams, some
fishes.
Reproduction and Development: Oviparous.
Lays distinctively large (up to 30 cm) egg
capsules in pairs on substrate; sometimes on
display in the sand dollar exhibit. Capsules
contain up to 8 embryos. Eggs hatch in about
9 months and produce a small, but perfectly
formed skate.
Mortality/Longevity: Life span: c. 15 years.
Conservation Status: Because they attain
sexual maturity late and produce fewer
offspring that most fishes, sharks, skates, and
rays are especially vulnerable to overfishing.
Remarks: Usually seen hiding motionless,
buried in sediments, with only the eyes
protruding.
Like all skates, swimming occurs by the
undulations of the pectoral fins.
A small fishery for this species exists in California;
its smaller “cousin” species are even more
popular as the source of the skate “wings” (the
pectoral fins) served in fine restaurants.
Bluespotted Stingray
Dasyatis kuhlii (Dasyatidae)
Whiptail Stingrays
Distribution: Throughout the tropical Indo-
West Pacific from the Red Sea east to the
Philippines, Japan, and south to Australia.
Habitat: Sandy bottoms near coral and rocky
reefs, from intertidal zone to 50 m. Moves onto
reef flats and into shallow lagoon waters at
high tide.
Appearance: Angular disc. Dorsal color
reddish-brown to olive drab with blue spots
and smaller black spots, ventral side white. Tail
with black and white bands is about as long as
the body and usually has one stinging spine.
Maximum disc width: 50 cm.
Diet: Crabs and shrimp, also small fishes.
California Academy of Sciences
95
R e p r o d u c t i o n a n d D e v e l o p m e n t :
Ovoviviparous; eggs retained in the female’s
body; embryos receive nourishment from a
yolk sac.
Mortality/Longevity: Killer whales are known
predators; probably also taken by other marine
mammals and sharks.
Remarks: Venomous tail can deliver a painful
wound. Like many other rays that wound
humans, it most often stings only when
inadvertently stepped on: it is difficult to see
in turbid waters, especially when covered by
sand with only the eyes visible.
Caught commercially, but its meat is of limited
value due to its small size.
Javanese Cownose Ray
Rhinoptera javanica (Myliobatidae)
Eagle, Cownose and Manta Rays
Distribution: Tropical, Indo-West Pacific from
South Africa north to India and possibly Thailand,
Indonesia and southern China. Also in Okinawa,
Ryukyu Islands and possibly Australia.
Habitat: Tropical bays, estuaries, among
mangroves, and near coral reefs over sand
and mud bottoms. Can tolerate brackish water.
Description: Bat-like, swept back pectoral fins.
Double-lobed snout and indented forehead.
Long, slender tail. Brown above, white below.
Width up to 1.5 m, weight up to 45 kg.
Diet: Feeds on clams, oysters and crustaceans.
The ray sucks in sand and expels it out of its
gills, blowing off sand covering its prey.
Reproduction and Development: Ovoviviparous,
1–2 pups per litter. Females have been
known to leap out of the water and slam into the
surface; this action seems to be an aid in birthing.
Conservation Status: IUCN listed: Vulnerable.
A declining population is inferred from the
unregulated nature of inshore fisheries as well
as small litter size.
Remarks: The stinger is located at base of the tail
rather than half way or more down the tail as in
the whiptail rays. Does well in captivity and has
been known to survive for 2 years. Like its pelagic
relatives the manta and devil rays, it swims by
flapping its pectoral fins like wings, enabling
it to swim at greater speeds than most bottomdwelling
stingrays. Sometimes these “wings”
protrude above the water, bearing a frightening
resemblance to a shark.