60 Sharks: The Animal Answer Guideback, including on its pelvic fins and the base of its tail. The spotting may
continue onto the outer margins on the undersides of the wings. Individu-
als can apparently be told apart by their spot patterns. (Researchers also
recognize manta ray individuals by the black spots on their otherwise white
bellies.) Unlike most other stingrays, Spotted Eagle Rays spend little time
resting on the bottom and much time “flying” around a reef.
Several chimaeras are relatively colorful, with deep reds, purples, and
blues, colors seldom found in elasmobranchs. Their names reflect these
color patterns: the Giant Purple Chimaera (Chimaera lignaria), the Purple
Chimaera (Hydrolagus purpurescens), and the Pointy-nosed Blue Chimaera.
How this coloration might interact with habitat and color vision remains a
mystery.
Color usually comes from pigments or structures that reflect light of
particular wavelengths (see “What causes the different colors of sharks?”
below). But at least six different evolutionary lineages of deep-sea squaloid
sharks have light organs on their sides that emit a greenish-yellow light,
often in patterns specific to a species. Examples include the Velvet Belly
Lantern Shark (Etmopterus spinax) and the dalatiid Cookiecutter sharks, the
latter discussed in chapter 2 with respect to teeth and in chapter 7 on feed-
ing habits. Cookiecutters can be considered micropredators or megapara-
sites, depending on your thinking. They live at middle ocean depths, where
many squid, shrimp, and deep-sea fishes also have light organs. Tunas, dol-
phins, sperm whales, Megamouth Sharks, White Sharks, and other pred-
ators descend into this cloud of illuminated prey to feed. Cookiecutters
are thought to hide among these other light producers, blending into the
background of flickering bioluminescence, then sneaking up on the larger
predators and removing plugs of flesh.Spotted Eagle Rays are among the
few rays that occur in tropical Pa-
cific, Atlantic, and Indian Ocean
waters. Often seen in small groups
in relatively shallow water, these
graceful, active rays are a favorite
among divers. Photo by John Norton,
Wikimedia Commons, http://en.wikipedia
.org/wiki/File:Spotted_EagleRay(Aetoba
tus_narinari) 2 .jpg
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