Is a Whale Shark a Whale or
6 November 1998
|Whale sharks are huge,
filter-feeding members of the family Rhicondontidae
and are actually sharks. They are the largest
fish in the world, even though they may seem
more "whale-like" because of their size
and the way they eat.
The whale shark (Rhiniodon typus) strains
small crustaceans and fishes out of the water with
sieves on its large gills. Some whales use similar
straining methods and are considered filter-feeders
consider it a special
treat to encounter a whale shark in the open ocean.
Whales, however, are mammals, not fish. Whales
have skin and hair, lungs and need to surface to breath
air. They are warm-blooded. Whale sharks have the tough
skin typical of other types of sharks, five gill slits and
Even though it catches its food by straining water through
its gills, the whale shark does have teeth -- several thousand
in about a dozen rows in its jaws. Each tooth is only 1/12th
of an inch long. When feeding, whale sharks sometimes stop
swimming and appear to be standing on their tails so that
they are vertical in the water. When they open their mouths
in this position, they gulp down krill and small fish.
The whale shark is gray-brown to reddish or greenish. It is distinguished by
a unique checkered color pattern made up of whitish spots
and bars. Its shape is somewhat different from other shark
species in that its head is wider than other sharks and
it has a humped back and a large lunate or crescent-shaped
tail. The whale shark probably gets its name from its size.
In 1919, a whale shark estimated at 60 feet was caught in
the Gulf of Thailand. It was so large, fishermen were unable
to haul it ashore, and no measurements were taken. The largest
accurately measured whale shark was a 40-foot, 7-inch male
caught in Bombay, India, in 1983. Its mouth was 4-feet,
6-inches wide and its pectoral fins were more than 6 feet,
6 inches long. By contrast, the blue whale, (Balaenoptera
musculus), the largest living whale and mammal, grows
to 98 feet in length.
Rhiniodon typus lives in the open sea and can be
found world wide; in the Atlantic it ranges from as far
north as New York to as far south as Brazil. It prefers
temperate or tropical waters.
The basking shark (Cetorhinus maximus) is similar
in size, but lacks the unusual color pattern. It is member
of a different family of sharks, the Cetorhinidae. Generally,
both the whale and basking sharks are considered harmless.
In fact, divers often refer to whale sharks as the "gentle