What is a Blue Shark?

Blue sharks (prionace glauca) are considered to be dangerous and are thought to be responsible for attacks on ship and air disaster victims.

Blue Shark Statistics

The largest recorded blue shark was 3.83m, but females average 2.76m and males 2.46m.

Blue Shark Physical Description

This species has a bright blue body, with a white underside. Not to be confused with a blue whale. It has a pointed snout with long pectoral fins (on the side of the body) and a streamlined body. Blue sharks have triangular, serrated teeth and large eyes.

Blue Shark Distribution

Blue sharks inhabit deep water in tropical, subtropical, and temperate seas worldwide.

What Do Blue Sharks Eat?

Blue sharks are voracious predators, feeding on schools of fish including anchovies, sardines, herring, and squid. Squid are important prey for blue sharks, but their diet includes other invertebrates, such as cuttlefish and pelagic octopuses, as well as lobster, shrimp, crab, a large number of bony fishes, small sharks, mammalian carrion and occasional sea birds.

Blue Shark Behavior – Do blue sharks eat people?

Blue sharks are a nomadic species and can travel hundreds of miles each year. They often gather in large groups. They are considered to be one of the fastest fish. Having been known to attack humans and boats, blue sharks are considered to be a dangerous species. Twelve unprovoked attacks and four boat attacks have been documented by the International Shark Attack File.

Do Blue Sharks Sleep?

Most fish basically enter a trance-like state when they sleep.  Sharks and other large fish may still swim, albeit at a slower rate than normal, in order to keep water flowing over their gills.  Blue sharks can lie on the bottom while actively pumping water over their gills, but their eyes remain open and actively follow movement.

When a blue shark is resting, it does not use its nares, but rather its spiracles. If a blue shark tried to use its nares while resting on the ocean floor, it would “inhale” sand rather than water. Many scientists believe this is one of the reasons sharks have spiracles.  It is also possible that blue sharks sleep while having a dedicated part in their brains that helps them keep swimming when the rest of their brain has gone to sleep. This is just like humans breathing even when they are sleeping. We have a part in our brain called the respiratory center that breathes automatically for us. So even when we are asleep, this center will make sure breathing happens unimpeded.

Blue Shark Reproduction

Females give birth to 25-50 pups, (although once, a litter of 135 individuals was recorded) after a gestation period lasting 9-12 months.

Is The Blue Shark an Endangered Species?

Blue sharks are classified as Lower Risk by the 2000 IUCN Red List.

How Long Have Sharks Existed?

Sharks existed before trees. They’re the same as current sharks, though they may have been much, much larger at varying points, but basically teeth in front, propeller in the back. We believe sharks evolved about 420mya in the Silurian period and widespread trees were not until around 380mya toward the end of the Devonian period. There were plants when fish and sharks were evolving, but they were more mosses and small vascular plants. No large forests. 

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