Common thresher sharks or Alopias vulpinus belong to the kingdom Animalia and are of the order Lamniformes. Their basic visual characteristic is a very long tail fin. They are great swimmers and can swim 550 meters below the sea surface. They use their tail to kill other fish. Common thresher shark is 16-20 feet long.
The unusually long caudal fin constitutes half of the total length of the shark's body. Its eyes have no pupil, which means that thresher shark's eyes are opaque in nature. Thresher sharks have the habit of jumping out of the water many times. This species is not as aggressive as other shark species, but can be dangerous, if provoked.
They usually do not cause any harm to the divers swimming around them. Lately, their population seems to be decreasing due to overfishing. Thresher sharks have great commercial value. They are valued for their meat and fins. Shark hides are used for leather, and vitamins are extracted out using its liver oil.
This commercial bend of the species has resulted in depleting population of these sharks. Since these sharks are slow in growth and reproduction, excessive hunting of the species may lead to their extinction. Let's check out each peculiarity of this aquatic animal.
Thresher shark is dark-blue and gray colored on the upper side and has a white color beneath. They have small yet strong teeth. Their mouth is placed behind their eyes and they have 5 gill slits.
These are found in tropical as well as temperate waters. They are commonly found in the temperate region. They inhabit in the Atlantic ocean, central and eastern Pacific ocean, and Indo-Pacific region. They are found in the coastal areas as well as deep in the sea.
They come near the coast in search of food and are found extensively in the region where abundant food is available for them. Young thresher sharks are usually found in the coastal areas whereas adults reside in deep waters of the ocean.
This species feeds upon Herring and Mackerel which are varieties of schooling fish. They also feed upon seabirds and squids. Their most common meal is Bluefish and Butterfish. They relish on Bony fish, which constitutes around 97% of their meal. Thresher sharks use their long tail to hit their prey and then feed upon them using their small yet strong teeth.
These are creatures who love to live alone. They are not socially active. They do not cause harm to divers unless provoked. They are sometimes known to harm boats owing to their large size.
Thresher sharks reproduce annually. They do not have a placental attachment and show aplacental viviparity, i.e., the eggs hatch inside the female shark and grow inside her body without any physical attachment. The young ones are 1.1 to 1.6 m long and weigh around 6 kg.
A pregnant thresher shark gives birth to around 4-6 young ones. It takes around 9 months to deliver the young pups. The reproducing capacity of sharks is less compared to other aquatic fish.
They do not have any predators. Though small thresher sharks are sometimes attacked by larger sharks.
Respiratory impairment is caused due the attachment of copepods in the gill filaments. Tissue damage occurs due to the attachment and results in improper respiration through gills.
Life Span and Maturity Age
There is a vast range in life span of thresher sharks. It ranges from 19-50 years. Females reach their reproductive maturity around 4 to 5 years of age, while males reach their reproductive maturity around 3 to 6 years.
These sharks are not fit for human consumption due to high mercury levels. Women and children below 12 years of age should avoid its consumption. Men should avoid eating more than one meal per month.
Certain facts about thresher sharks must be clear by now. It is clear that this species is not so dangerous to human life. It is also evident that it is not a good sea food and hence, must be avoided. It is the responsibility of human beings to let this beautiful creature be in the ocean peacefully.