Coloring in any animal depends upon whether the animal is a predator or prey species, whether it's venomous, poisonous or essentially harmless. Because sharks tend to be top-of-the-food-chain predators, their colors are not usually flashy. For the most part, sharks depend upon counter-shading to blend with darker, murky colors of deep water when viewed from above, and lighter colors of sky and shallow water when viewed from below, to help catch their prey by surprise.
Just as we tend to wear neutral colors when we don't want to stand out, so sharks depend upon understated colors to keep them as unobtrusive as possible. Many more recognizable sharks around the world fit this category. The great white shark (Carcharodon carcharias), bull shark (Carcharhinus leucas) and bronze whalers (Carcharhinus brachyurus) are examples of sharks that lean toward neutral grays with creamy underbellies -- employing counter-shading as insurance against detection from above or below. All three species inhabit coastal waters and prefer hunting near shorelines. The bull shark is also sometimes found in freshwater -- traveling far up rivers from ocean outlets.
A Bit of Flair
Some sharks jazz up the basic color schemes -- gray, brown, tan or white -- with added stripes, spots or other patterns. Not that these embellishments are particularly flashy -- most are practically unnoticeable as only slightly darker or lighter shades of the overall body coloring -- but they serve as distinguishing marks for identification. They also break up the shark's body lines to mimic nearby substrate, which helps the shark blend into the background. Tiger sharks (Galeocerdo cuvier) and broadnose seven-gill sharks (Notorynchus cepedianus) are good examples of this sort of faint, same-color patterning. The broadnose, in particular, is interesting because its varied-sized speckles and spots look like the sandy bottoms and rocky shorelines that it frequents while hunting.
Not many sharks go all out for colors and patterns, but among those that do, some are real show-stoppers. For general elaborateness of ornament it would be hard to beat the wobbegongs of the Australian coral reefs. Their assorted green, yellow or brown blotches, lines, squiggles, spots and O-shaped rings are decorative enough, but with the oddly-shaped fleshy protuberances around their bodies, they look like something between a fringed rug and an entire coral reef. The ornate wobbegong (Orectolobus ornatus) and the tassled wobbegong (Eucrossorhinus dasypogonare) are especially distinctive members of the unusual shark family Orectolobidae.
Dazzling Light Show
An inconspicuous tan-colored wallflower by day, the cookie-cutter shark (Isistius brasiliensis) pulls out all stops at night. One of the rare sharks to display bioluminescence, it uses its built-in light show to lure much larger animals close in where it can take a bite out of them. It does this by lighting up its belly in a greenish glow using special light-emitting organs called photophores. The entire underside glows except for one small fish-shaped area. When a predator comes close to eat the “fish” -- highlighted from behind by what appears to be sky -- the sneaky cookie-cutter shark bites, twists and dashes away with its meaty prize -- leaving a deep, circular, cookie-cutter-shaped wound on its victim. Many whales, porpoises, sharks and other marine mammals bear distinctive circular scars from the work of this clever, hit-and-run shark.
Saving the Best For Last
When you're the largest fish in the sea, you're going to get noticed anyway, so you might as well look good. The whale shark's (Rhincodon typus) all over white stripes and dots on a dark, gray-brown background are so precisely delineated they look beautifully painted on and anything but understated.
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