10 Blue Shark Facts

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Blue_shark_Prionace_glauca
Blue shark (Prionace glauca). Author: Mark Conlin, SWFSC Large Pelagics Program, PD image.

10 Blue Shark Facts

Blue_shark_Prionace_glauca
Blue shark (Prionace glauca). Author: Mark Conlin, SWFSC Large Pelagics Program, PD image.

Say “shark” and the fearsome great white shark immediately comes to mind. However, there are over 400 other species of sharks in the ocean, one of which is the elegant blue shark.

The blue shark is considered one of the most beautiful sharks in the world because of its slim body, long fins and cone-shaped snout. Its scientific name is Prionace glauca. Prionace comes from the Greek words prio (“saw”) and akis (“pointed”), probably referring to its teeth, and glauca comes from the Greek word glaukos, meaning “bluish gray”.

Indeed, the blue shark is not entirely blue. It is dark blue on top, which is where it gets its name from, and grayish on the underside. This countershading is meant to prevent the blue shark from being seen easily. From above, the dark skin makes it blend in with the water and from below, the lighter side seems invisible against the sunlight.

Here are some other facts about the blue shark.


1. They can grow over 6 feet (1.8 meters) long.

Blue_shark_Prionace_glauca
Blue shark (Prionace glauca). Author: NMFS, E. Hoffmayer, S. Iglésias and R. McAuley, PD image.

The blue shark is a medium-sized shark. The females grow 7 to over 10 feet (2.1 to 3 meters) long — as long as a recreational kayak — and weigh 200 to 400 pounds (91 to 181 kilograms), about as heavy as a calf. The males are 6 to 9 feet (1.8 to 2.7 meters) long and weigh 60 to 120 pounds (27 to 54 kilograms). The females are larger than the males because they have to be big enough to carry their babies. Also, females have three times’ thicker skin than males because the males tend to bite during the mating process.

The largest blue shark ever caught was 12.6 feet (3.8 meters) long and weighed over 800 pounds (363 kilograms).




2. They are the most widely distributed shark species.

Range_of_blue_shark_(Prionace glauca)
Range of blue shark (Prionace glauca). Image credit: Maplab, (CC BY-SA 3.0)

Blue sharks are pelagic sharks, which means that they are found in open waters, neither near the ocean floor nor near the shore, often spotted just below the surface in deep waters. They are found all over the world, as far north as Norway and as far south as Chile, off the coasts of every continent except Antarctica. They prefer cool waters, though, below 68 degrees Fahrenheit (20 Celsius). They are often seen off the coasts of Wales, Canada, Japan and South Africa.

Blue sharks migrate long distances in search of food, traveling from the Atlantic to the Pacific and back again. They can migrate as long as the distance from New England to South Africa.


3. They live in groups.

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An example of a Shark school (school of Scalloped hammerhead sharks). Image credit: Ryan Espanto, (CC BY 2.0)

Many sharks are solitary, but blue sharks live in small groups called schools. Some of these groups consist only of females and others consist only of males. Within each group, there is a certain order, with the largest member often being the leader of the group. They travel in these groups for protection. Long journeys can be dangerous, after all. They also hunt in groups.


4. They like to eat squid.

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Blue shark (Prionace glauca) feeding on squid, Southern California Bight. Image credit: Image credit: Jim Benante, NOAA/NMFS/NWFSC/FRAMD/MF

Blue sharks prefer to eat squid and they often travel to the squids’ breeding grounds in order to hunt. When squid is not available, though, they eat cuttlefish, octopus, lobster, crab, shrimp, smaller sharks and bony fishes. Apart from being hunters, they are scavengers, consuming dead whales and dolphins.


5. They have lots of babies.

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Female Blue shark at Banco Condor, Faial, Azores. Image credit: Patrick Doll, (CC BY-SA 3.0)

Blue sharks are viviparous, which means their young develop inside a placenta, just like in mammals, and then they are born as live young, or pups. Blue sharks are known to have large litters, from 50 to 134 — that’s large, considering that the great white shark (which is about twice their size), has only an average of ten pups. The larger the female, the more pups she is likely to have. The female blue shark carries the pups for nine months to a year, and then abandons them after they are born. Each pup is around 16 to 20 inches (41 to 51 centimeters) long.


6. There has been a two-headed blue shark.

two-headed_blue_shark

Pregnant blue sharks caught by fishermen are opened up, with some of the young thrown back into the sea. In one of these cases, a two-headed blue shark pup was found inside its mother’s belly, each head having its own set of eyes and teeth. According to scientists, this occurs when two embryos combine while developing, the same reason that Siamese twins — twins with joined bodies — are born. The two-headed pup seemed healthy at first, but it couldn’t swim properly and eventually died.


7. They are eaten by sea lions.

sea-lion
Sea lion by Unsplash, PD image.

Blue sharks have a few predators, including larger sharks such as the mako and the great white. They are also eaten by sea lions and seals, who eat just their stomach and liver!


8. They rarely attack humans.

In close to 500 years, there have only been thirteen reported attacks by the blue shark, and only four of those were fatal. That makes them less deadly than most sharks, like the great white, the tiger, the bull shark, the blacktip shark and the spotted wobbegong shark. Still, blue sharks are known to feed on shipwrecked sailors and are by no means timid — plus, as we said, they live in groups, so one must be careful around them. Blue sharks often circle before they attack, for 15 minutes or so, then give an exploratory bite.


9. They are not endangered but are widely hunted.

Peter_van_der_Sluijs_from_Spijkenisse_with_a_blue_shark_caught_in_Ireland
Peter van der Sluijs from Spijkenisse with a blue shark caught in Ireland. By Peter van der Sluijs GFDL

Currently, the blue shark is not classified as an Endangered species. Rather, its status is Near Threatened. What this means is that its population has been going down, though not yet at an alarming rate. Every year, millions of blue sharks are killed, either by hunted or being accidentally caught in nets. They are hunted for sport and like other sharks, for their skin, their fins and their liver.




10. They do not do well in captivity.

shark_aquarium
Shark aquarium by Hans, PD image.

Never seen a blue shark in an aquarium? Not to worry. The truth is that many sharks do not do well in an aquarium and the blue shark is among them. Even in spacious, circular tanks, the blue shark has only survived for as long as 7 months, dying because of stress or illness. Needless to say, you also can’t keep a blue shark for a pet.


Blue Shark Videos.

The YouTube video below contains a playlist of 5 Blue Shark videos to have a look at, the list of videos featured is underneath.

  1. Blue Shark Encounter by Scott Tucker – Awesome underwater video of blue sharks.
  2. An Afternoon with Blue Sharks by BlueOceanProductions – At least six blue sharks filmed off Anacapa Island.
  3. Charles Maxwell – HD – Blue & Mako Sharks – Charles was a 2002 Primetime Emmy Award winner in the category Outstanding Cinematography for work done for The Blue Planet.
  4. Mako bites Blue shark – Footage from Hokianga, New Zealand Feb 2012.
  5. Diving with Blue Sharks – Azores – Diving with blue sharks in the Azores off Faial island.

Sources:

http://en.wikipedia.org/wiki/Blue_shark
http://www.sharks-world.com/blue_shark/
http://www.sharksider.com/blue-shark/
http://atlanticsharks.org/shark_species_details.php?id=2

Click here to view the complete list of sources…

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