Thresher shark

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The thresher shark is a medium sized shark found in open ocean waters around the world. These weird sharks contain three species: the common thresher, the pelagic thresher, and the big-eye thresher. Thresher sharks are easily recognized by their large tail which can be as long as the rest of their body, and can be as much as one third of the weight of the entire body! These tails have an interesting use when it comes to hunting. The thresher shark, like the bull shark, exhibits counter-shading. This means that their top half is dark (in this species a grayish-blue) and their bottom half is white in order to blend in with the water or the sunlight. Thresher sharks are sometimes also called fox sharks. To see a video about these amazing sharks click here.

Size

Thresher sharks can grow up to 20 feet (6 m) long including their tails. This measurement is for the largest species: the common thresher shark. These sharks also weigh a lot, but the exact maximum is not known. Some individuals have been recorded weighing over 1,000 pounds (454 kg)!

Use of tail

For many years, the exact use of the thresher shark’s tail was not known. Many scientists speculated that it was used to stun fish before eating them. There had been no definite proof of that until 2010. Over twenty-seven days, a team recorded almost 11 hours of thresher sharks attacking a baited line. Fourteen of the thirty three thresher sharks that came attacked the line with their tail and hit the bait sixty-five percent of the time. The team noticed that the sharks attacked the line with two different versions of tail strikes. Some of the sharks wiggled their whole body while moving quickly forward. By the time the end of their tail got to the bait, it was travelling fast enough to hit the bait quite hard. The rest of the sharks swam until they were right alongside the bait. Not until then did they flick their tail to hit the bait.

Diet

Thresher sharks eat a variety of marine animals depending on the species. Some will use their tail to corral and stun groups of fish such as sardines. Due to their small teeth and jaws, they cannot easily capture a wriggling fish and normally stun their prey first using their tail. Along with fish, they also feed on octopus, squid, and crustaceans. In rare occasions, seabird remains have been found in a thresher shark’s stomach.

Agility

Thresher sharks are able to swim at high speeds for long periods of time even in cold water. This is thanks to a special red muscle that runs along the side of a thresher shark. This muscle rarely gets tired. They are able to swim in cold water because this same muscle contains tiny blood vessels that send heat throughout the body.  Thresher sharks also can jump a ways out of the water.

Threats

Due to their size, Thresher sharks have very few natural threats. Humans often catch thresher sharks on their lines after a long hard fight. Frequently, a thresher shark will hit the bait with its tail and then get caught by its tail.

 Birth

Although these sharks normally mate in the spring, they have been reported doing it year round. Thresher sharks are ovoviviparous meaning the young are born fully formed, not in eggs. While they are developing inside their mother, cannibalism often occurs with stronger young eating other weaker siblings. This does not always happen however and sometimes after a nine month pregnancy up to seven young, or pups, are born. 

Young, maturity, and social life

After birth, the young, which can be up to five feet (1.5 m) long, stay in a nursery for up to three years. These nurseries are made of multiple pups in a shallow area, and no adult thresher sharks are there. Even in smaller sharks, large numbers helps protect them from larger sharks which could easily eat them. Male thresher sharks start mating as early as age 9, but the females wait until age 12 or later. Most of the time thresher sharks are solitary, but they will sometimes work together to corral fish into tight groups.

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Sources:

Photo credits:

  • Thresher shark – Petter Lindgren
  • Mystery animal – public domain

One Response

  1. Lana
    Lana at |

    Quite an interesting tail!

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