There is a species of shark that is not widely researched due to their habitat, known as the Thresher shark and there are three different species of this shark; Common Thresher, Pelagic Thresher and the Big eye Thresher. The largest of these is the Common Thresher and the smallest being the Pelagic Thresher.

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Three species of Thresher shark – image credit Google

 

Morphology

The Thresher shark has an unusually large caudal fin (tail fin), as long as the sharks body itself. The fin resembles a ribbon when swimming but is extremely powerful when flicked. The Thresher shark will use its tail to stun or in most cases kill its prey, this is possible as they have the ability to “whip” their tails.

Thresher sharks vary in colour, ranging from a metallic brown to blue on their dorsal side (top part of their body) and their underside is white.

Reproduction

Thresher sharks are slow growing, will reach maturity between the ages of 8 years old and 13 years old, and will live to about 22 years old. They are viviparous produce; meaning they give live birth, the pups when born can be more than 3ft long. The litter size is small: 2- 7 pups.

Hunting

They have teeth that are small, smooth and curved yet razor sharp. Their teeth don’t have to be great in size as they are not hunters of mammals but of smaller organisms such as; squid, crustaceans, bluefish, needlefish, mackerel, sardines and other small schooling fish.

The way in which this species hunts and feeds is carried out by the shark accelerating towards a school of fish and then by twisting its pectoral fins in order to stop abruptly. It will then lower its snout, pitch its entire body forward and flex the base of its tail. By doing this it is then able to “whip” its tail through the school of fish and this will then either stun or kill the fish; the whip of a Thresher sharks tail has even been known to dismember its prey. The shark will then swim back around and eat the fish it has lashed. Even though this specific species of shark hunts in this way, they are only successful on a third of their strikes. However, they tend to kill multiple fish with one whip of their tail meaning that the don’t rely on direst hits. The way in which these sharks hunt suggest that it is more efficient than chasing after agile fauna in an unclear shoal and using valuable energy for catching prey.

Thresher sharks tend to hunt at night in the open ocean which is why there is minimal research and observations on their behavior and hunting techniques.

Adaptations

These sharks can keep their body warm unlike most sharks, allowing it to exploit habitats that other sharks can’t. They are also found all over the world, in warm and temperate waters. However, they prefer cool pelagic waters and will pursue shoals of fish to coastal waters. This gives them a distinctive advantage in a competitive ocean environment, however they commonly hunt schools of fish.  There are reports that the Monad Shoal near the Philippine Islands of Malapascua are the only place where divers arable to spot Thresher sharks on a regular basis.

Tail speciality

When Thresher sharks whip their tails, it goes through a process where bubbles form in a liquid due to rapid movement, typically by a propeller.  A Thresher shark will create this by causing the pressure in front of them to lower in turn causing the water to boil, small bubbles are then released and collapse again when the water pressure equalises. Another organism that uses cavitation to attack is the mantis shrimp. It has been recorded that the Thresher shark has the ability to whip its tail at an average speed of approximately 30 miles per hour.

 

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Thresher shark showing its long caudal fin – photo credit Google (Wikipedia)
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