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Tuesday, October 16, 2018

Maritime Logistics Professional

Whale shark

Posted to Maritime Musings (by on October 12, 2012

The world’s largest fish

The whale shark is found in all the tropical and temperate marine waters except, so far as is known, the Mediterranean Sea and the Black Sea.  It grows up to 20 meters in length and can weigh up to 30 tonnes.  It is the largest living non-mammalian vertebrate (exceeded only by the blue whale) and nearly as heavy as a large dinosaur.  It was first scientifically described based on a specimen that was harpooned in Table Bay, South Africa in 1848.  The whale shark has a streamlined body and a depressed, broad, and flattened head.  It features a unique checkerboard color pattern of light-colored stripes and spots on a dark gray background.  The whale shark, belying its huge size, feeds almost exclusively on plankton, small crustacean, and small fish.  Unlike most other filter-feeders, though, it actively sucks its food into its large mouth and then forces the filtered water out through its gills.  Most other filter feeders depend on a slow forward movement through the water to conduct the filtering.  The whale shark can feed while virtually still in the water, moving only its mouth and gills.  The female whale shark is ovoviviparous, giving birth to up to 300 live young at a time.  The gestation period is presently unknown.  Commercial fishing of whale sharks is carried on at a minimal level in waters off Taiwan and the Philippines.  The whale shark is listed as vulnerable by the International Union for Conservation of Nature and Natural Resources (IUCN).  A recent threat to the whale shark is the growth of shark tourism.  In certain areas, such as Western Australia and near Cancun, tourists can now pay for excursions to see these creatures in the wild.  This presents several problems.  The activity disturbs the whale shark and its usual food sources.  Also, some tour boat operators have been known to dump shark food into the water to attract the whale sharks.  This may lead to sharks to become dependent upon the artificial food source.  The whale shark is harmless to man.  Unfortunately, the opposite is not true.


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