The Porbeagle Shark Hunts With Dogged Determination

Many creatures depend on their environment to warm their bodies. When these animals get too cold, they'll often need to heat up by physically relocating to warmer places. Failure to do so can have dire consequences.

Some heat is naturally produced by exercising certain muscles. However, in most known sharks, that muscle-made warmth rapidly exits the body and dissipates into the surrounding water.

Porbeagles and great whites are some of the few sharks with a built-in countermeasure. Namely, they've got a distinctive system of branching veins and arteries that run parallel to each other.

The apparatus is called the rete mirabile, which means "wonderful net" in Latin. Its job is to redirect the heat that muscles and organs generate as a byproduct. Instead of leaving the shark altogether, this precious warmth is rerouted to colder parts of the body.

Therefore, porbeagles — much like great whites — can maintain a core body temperature that's around 5 to 14 degrees Fahrenheit (or 3 to 8 degrees Celsius) warmer than the water they happen to be swimming around in.

Porbeagles like it cool; the species can tolerate water temperatures of 73 degrees Fahrenheit (23 degrees Celsius), but it tends to favor colder habitats.

Above the equator, you'll find no porbeagles in the Pacific Ocean — although a similar species, the salmon shark, does frequent those waters.

Elsewhere in the world, porbeagles are widespread across the North Atlantic and the Mediterranean Sea. They also hang out along the southern coasts of Africa, Australia and South America. New Zealand is another porbeagle hotspot.

An athletic killer, the porbeagle will chase down everything from mackerels and herring to dogfish and squids. Sometimes, these predators break the water's surface and go airborne while hunting.

The average natural life expectancy of Lamna nasus is 30 to 40 years. Female sharks are ready to breed at age 13 or so; males mature a little faster (imagine that).

Developing embryos consume egg yolk inside the uterus. Babies are subsequently born live in litters of one to five pups. And yes, in case you hadn't heard, a baby shark is called a "pup."

At birth, infant porbeagles are a meager 24 to 30 inches (60 to 75 centimeters) long. Very young sharks may feed on seagoing worms known as "polychaetes."

Porbeagles are formidable hunters, no question. But that doesn't necessarily mean they're all business.

Off the shores of Cornwall in Southwest England, porbeagles have been known to tinker with kelp, winding it around their snouts before unraveling the stuff — and then starting the whole process over again. Other porbeagles may get involved by chasing their kelp-wrapped peers around. Nobody knows why. Perhaps these sharks were only searching the kelp for prey. Or perhaps they were trying to scrub away their skin parasites.

Or maybe — just maybe — the fish were doing something that humans, dogs, elephants, iguanas, turtles and lots of other animals practice from time to time: play behavior.

As in spontaneous, voluntary activities: recreational antics performed by healthy individuals which stimulate the senses but do not immediately benefit their chances of survival. That sort of thing. It's a fascinating topic — but at the end of the day, scientists aren't sure if porbeagles actually play or not.

By the way, here's another unsolved mystery: Where on Earth did the name "porbeagle" come from?

In "The Sharks of North America," author José I. Castro lays out several possibilities. "According to the Oxford English Dictionary," he writes, "the name is of Cornish origin and possibly derived from the French porc (swine) or porpoise (porcus pisces = hog-fish or fish-hog) and beagle."

Adorable as beagles are, the pooches were bred to be hunting dogs originally. So it might not be amiss to compare Snoopy's brethren with a tenacious little shark. We don't think Charlie Brown would mind....

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