"Creature of the Month"
                                                                        

                                                                                              August 2004
 
 
 
 
 

The Tiger Shark

Order                                         Family                                   Genus and Species
Carcharhiniformes                     Carcharhinidae                       Galeocerdo cuvier

Tiger sharks are large, powerful sharks which are solitary hunters and live in the warm coastal
waters of the worlds tropical seas.  It is not uncommon for this species to swim up to 55 miles
per day in search of food,  but the streamlined features and fluid, effortless swimming style of
the tiger shark makes the need for frequent rest periods a needless undertaking.

Tiger sharks are so named for the dark stripes along their backs which somewhat resemble a
tigers stripes.  As the shark matures, the stripes will eventually fade.  These sharks do not like
cold water and will follow warm water currents as far south as New Zealand and the upper
United States.  In winter, tiger sharks live and feed in deep water around coral reefs.

This shark species will eat anything, with an emphasis on anything.  Tiger sharks, when cut
open have been known to have eaten shoes, license plates, lengths of rope and chain and
other indigestable objects.  Their main diet consists of squid, fish, smaller sharks and seals.
They are dangerous because they will attack anything in the water are are definite maneaters.
They rank #2 on the list of known attacks against humans, right behind the Great White which
ranks #1, but they rank#1 when discussing fatal attacks against humans.

It has an extraordinary sense of smell, and almost two-thirds of its brain is dedicated to the
processing of information relating to scents.  Their sense of smell is so advanced and keen
that they can "smell" blood in the water from over a mile away.  It is also sensitive to the
slightest low-frequency pressure waves created by someone or something thrashing around
in the water.  Sensitive electro-receptors (pits located between the eyes and mouth) can
home in on the slightest movement in water and can locate their prey even in total darkness.

When a tiger shark loses one of its teeth, it will grow another one to replace the lost or broken
tooth. Its wedge shaped head makes it easy for the shark to turn quickly from one side to the
other.. It can weigh up to 2,200 pounds, on average, and is usually 10 to 16 feet long, but can
grow up to 23 feet long. It has a long upper tail lobe that helps to propel it swiftly through the
water when it is trying to capture prey.  The gestation period for tiger sharks is around 9 months.
This species has a lifespan of between 30 and 40 years.

Sharks need to keep up a forward movement to keep fresh aerated water flowing across it's
gills (numerous slits along the sides of the shark in front of, and slightly above,  the pectoral fins)
These are the respiratory organ of most aquatic animals that breathe water to obtain oxygen,
consisting of a filamentous structure of vascular membranes across which dissolved gases are
exchanged.

The tiger shark does not have as much commercial value as other sharks and,  although they are
sometimes hunted as a sport fish, there is immediate threat of their being added to the endangered
species list.  The female diver in the above graphic evidently has lots of nerve...tiger sharks are
very unpredictable and will sometimes turn on divers who are trying to tag or interact with them.

The area of the world where tiger sharks are located is shown in dark blue in the following graphic.

Check back for September's "Creature of the Month"....The American Harpy Eagle.

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