Friday, August 16, 2013

Fun Friday Facts #82: Sharks

It was Shark Week last week, and did you know that 80 percent of people who get attacked by sharks survive? So, if you’re terrified of sharks like my friend, Sharky-Sharky No-Legs, rest easy.

Sharks are fascinating, which is of course why they have their own week. I also did whales last week, so sharks kind of go along with that theme, in that both are sea creatures.

The first sharks are believed to have appeared as long as 420 million years ago, making them literally older than God. Modern sharks began to appear around 100 million years ago. One of the oldest sharks is the Cladoselache, which dates from about 370 million years ago:

I was going to make a joke about how funny it looks, but then I remembered that sharks are still kind of weird-looking.

"Stop, you'll make me cry."
Image credit: Hermanus Backpackers

One of the biggest predators that ever lived was the Megalodon, a shark that lived from 28 to 1.5 million years ago and is now extinct.

The Megalodon grew to sizes ranging from 46 to 59 feet (14 to 18 meters). Regular readers will remember that it was the Megalodon’s giant, fossilized teeth that protected many Europeans from poisoning throughout the Middle Ages – or so they believed. Shockingly, dipping a shark’s tooth – even one that is the size of a toddler’s head – into your poisoned wine will not make it safe to drink.

But I can see why they would think that.

Sharks are cartilaginous fish, like rays and skates. Their skeletons are made of cartilage. The reason there are so many fossilized shark teeth floating about is because they are made of calcium phosphate, which fossilizes easily. Also, a shark may lose more than 30,000 teeth in its life, replacing them at a rate of once every eight days in some species.

Most shark species grow multiple rows of replacement teeth on the inside of their jaws, which move forward as if on a conveyor belt. The exception is the cookiecutter shark, which replaces entire rows of teeth at a time. It feeds by biting round chunks out of its prey, and has been known to attack whales, dolphins, porpoises, other sharks, and submarines, which it finds to be an acquired taste.

It also looks like a swimming penis.

Because a shark has no rib cage, it can be crushed under its own weight if brought onto land.

Most sharks can’t live in fresh water, although there are at least two species – the bull shark and the river shark – which can. The bull shark is one of the most dangerous species known to man, along with the great white, the oceanic whitetip and the tiger shark, because they are most often found in shallow waters where humans are wont to play around looking like seals.

In fact, a couple of years ago, a fisherman named Willy Dean caught an 8 foot, 1 inch (2.5 meter) bull shark in the waters of the Potomac River, at Cornfield Harbor. Just two days earlier, Dean’s friend Thomas Crowder captured an even bigger, 8 foot, 3 inch (2.51 meter) shark a little upstream, at Tall Timbers. Though Crowder’s shark drowned and he discarded its corpse, Dean elected to keep his.

“Some people say shark is good to eat. We’ll see,” he told journalists.