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Blue Shark Facts and Information

[Phylum: Chordata] [Class: Chondrichthyes] [Subclass: Elasmobranchii] [Family: Carcharhinidae]

Generally they are not aggressive towards humans. But this open ocean pelagic predator shark is better known for its sleek body and ultramarine blue colouring on its back.

This section contains fun and interesting facts about blue sharks (Prionace glauca), including what they eat, where they live, and how they reproduce.

Blue Shark Habitat and Geographical Range

Prionace glauca is one of the most widespread of all 500 shark species that roam the world's oceans.

But, they thrive best in the sunlight zone (epipelagic) of temperate and tropical waters, especially:

The blue shark is one of the requiem sharks. It's a migratory species that inhabits the deep offshore waters as well as the shallow coastlines of temperate seas.

Blue sharks have the largest migration patterns of any shark species. For example, after breeding off the coasts of North America and the Caribbean, the Atlantic blue shark heads to the waters of western Europe and north Africa.

Then...

Later in the year, they return to the western Atlantic coastlines to start the breeding process again, covering a total distance of around nine thousand (9,000) kilometres.

Prionace glauca is the species name for the blue shark, and some countries refer to it as the great blue shark. But, this inquisitive creature has several other common names, including the blue dog and the blue whaler.

Blue Shark Characteristics and Behaviour

The blue shark has several distinguishing features. But, the most striking is the "countershading" that it gets from the deep blue indigo colouring on its back and the way it contrasts with its white underbelly.

In addition, this streamline shark has a slender body with a long pointed and somewhat conical snout. Despite the small mouth, it has sharp, saw-edged, triangular teeth.

The dorsal fin is small, but the pectoral fins are elongated and slimline - perfect for slicing through the water like a scythe.

Fun Fact: The blue shark (P. glauca) is one of the fastest swimming sharks in the world. Its elongated tail fins and aerodynamic agile body can reach speeds up to sixty nine (69) kilometres per hour (43 mph).

Blue Shark Size and Weight

The eyes of blue sharks are big and round. If you get close enough, you may even see the disk-like white patches that surround the eye sockets.

Behind the retina, the tapetum lucidum enhances the shark's vision in low light (e.g. in deep water and at night).

Here's the thing:

Its head contains small freckle-like pores. These are the electrosensory organs that pick up any weak bioelectrical fields given off by its prey.

At full maturity, male blue sharks usually grow up to 3 metres long (11 feet). Even so, the biggest blue shark was a female measuring more than four (4) metres long (15 feet) and weighing around 200 kilograms (454 pounds).

Scuba divers beware!

In fact, there are about thirty shark species that attack humans, including the requiem sharks. By and large, blue sharks are mostly docile, human-friendly fishes that prey on small animals. Even so, they will bite in defence and documented cases of blue sharks biting humans do exist!

Pro Tip: If you are wondering what animal kills the most humans in the world, it is definitely not the blue shark!

What Do Blue Sharks Eat?

Despite being a typical carnivore, adult blue sharks don't generally eat other sharks. But, they use their superior swimming speed to hunt and catch their favourite prey invertebrate cephalopod molluscs, most slow-moving fish species, and a variety of other animals, including:

In general, pelagic sharks are not usually a social species. But, it's common to see groups of blue sharks gathering to feed together when hunting large schools of prey.

Pro Tip: The index sections contain many more examples of vertebrates fish with extra information about how the different types of marine invertebrates influence the food chain in aquatic environments.

How Do Blue Sharks Reproduce?

The sexual dimorphism in this shark species means it's easy to identify the adult females. They are bigger than the males and they have thicker skin.

Male blue sharks reach sexual maturity from the age of five (5). Whereas, the females tend to mature a few years later and start to get sexually active after they are six years old.

And the outcome...

The mating ritual begins when a male starts to bite a female in the patch between the two dorsal fins. Hence, this is the reason why the skin on the back of female blue sharks is thick and tough.

A typical gestation period is nine to twelve months. But, being an ovoviparous species means they give birth to live pups.

An average litter size for blue shark pups is 35 to 50. But, the largest litter size ever recorded is 135. The newborn pups will be about thirty eight (38) centimetres long (15 inches) when they leave the womb.

Interesting Fact: When they're not hunting for food, juvenile blue sharks often group together in gender-specific schools, or pupping zones, maybe for protection against their natural predators.

Threats and Predators

The blue shark is quite a robust fish, and it will tolerate capture and a degree of man-handling. For this reason, the species has become an important part of several shark research and conservation projects.

Despite that fact, blue sharks are the most heavily fished of all sharks in the world (about 60%). The protection of the species is difficult because blue sharks migrate across so many international borders.

Blue Shark Lifespan

Even though most blue sharks live up to about 15 years old in the wild, it is rare for them to live beyond the age of eight (8) when kept in captivity.

Most of the severe threats for the long term survival of the species come from bycatch (overfishing by commercial fishing fleets for the meat and fins), marine garbage pollution, and from sportfishing activities.

Important: The IUCN Red List of Threatened Species is a comprehensive source of information about the global conservation status of animals, fungi, and plants. In 2018, IUCN listed the blue shark as Near Threatened (NT) - especially in the Atlantic and Indian oceans.

Related Information and Help Guides

Note: The short video [2:11 seconds] presented by "Deep Marine Scenes" contains footage of the sleek and slender blue shark swimming in its natural habitat.

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