Shark Colors 59
goatfishes, and sweetlips, but how this color helps these fishes remains a
matter of debate.
Perhaps strangest of all is the Goblin Shark (Mitsukurina owstoni), with
its long, daggerlike snout, protrusible jaws, and slender, fanglike teeth.
This deepwater (around 500 m) rare lamniform has a body that is soft pink
to purple-gray, with blue-edged fins. Its color is due neither to pigments
nor structural iridescence but to blood vessels that lie close beneath the
skin, which is itself fairly transparent.
Rajid skates as a group are plainly colored, except for those with paired
bull’s eyes on their pectoral fins and backs. Many other skates, including
the Spotback Skate, Atlantoraja castelnaui, have small black spots. Others,
such as the Undulate Ray (Raja undulata) and the Sydney Skate (Dipturus
australis), sport wavy lines and white spots reminiscent of Australian Ab-
original bark paintings, which may have been inspired by these batoids or
by the color patterns on a Whale Shark.
Colorful stingrays are also the exception. Interestingly, several of these
have blue spots and stripes. Blue is a pigment almost entirely absent from
the selachian sharks, except for some open-water species like Blue Sharks
and makos, whose countershading includes deep-blue backs. The Blue-
spotted Stingray (Dasyatis kuhlii) of the tropical Pacific has blue spots on a
greenish background. It is also one of the few rays thought to be able to see
colors (see “Can sharks see color?” in chapter 2). The Bluespotted Ribbon-
tail Ray (Taeniura lymma), also a tropical western Pacific reef species, has
electric blue spots on a yellow background, with two blue stripes running
the length of the tail. Some of the most colorful rays are the potamotrygo-
nid freshwater stingrays of the Amazon Basin. The backs of these animals
are spotted and streaked, often in (again) bright blue. Freshwater stingrays
have powerful venom in their tail barbs, tempting an interpretation that
their bright, contrasting colors serve to warn potential predators of these
effective defenses.
One species of electric ray, the Ornate Sleeper Ray (Electrolux addisoni)
of South Africa has a dark brown back with small yellow spots and curving,
concentric black stripes. When it is approached by a diver, the ray arches
its back, curls its disk, and raises its tail in what might be a threat display.
Bold, obvious “warning” coloration and conspicuous body postures occur
in a wide variety of animals with toxic properties, from wasps to caterpil-
lars, poison dart frogs, and skunks. Electrolux addisoni also holds the distinc-
tion of probably being the only elasmobranch (or any animal?) whose ge-
nus name honors a brand of vacuum cleaner and reflects both its electrical
traits and its suction-feeding behavior.
The large, graceful Spotted Eagle Ray has distinctive white, bluish-
white, greenish, pearly, or yellow spots on a black background across its