Journey of Life - Seas of Life 9
Steve travels back 3.8 billion years to when life began. Journeying round the oceans, he explores life's first laboratory and discovers how the incredible variety of sea creatures arose, from the first microbes to hagfish and dolphins.
Once primitive fish had developped jaws, an extraordinary range of teeth evolved to fit them. Shark's teeth are adapted to the diet of their owner. The sand tiger has narrow pointed teeth for seizing slippery fish and squid. Other teeth, like the seal shark's, are multi-pointed for feeding on the ocean floor, picking up crabs and shellfish. The snaggletooth's varied diet, needs a tooth like a hunting knife, while the tiger shark’s are more like chainsaws, used to tackle turtle-shell and fish-bone. And these belong to the biggest meat-eating shark alive today – the great white. They slice through the meat of sea mammals.
The biggest teeth of all belonged to the Megalodon--a bus-sized meat-eating monster that was 12 times bigger than a great white shark. Its jaw was colossal--over 2 meters wide with hundreds of teeth. It could have swallowed me whole.
Good job is it's extinct. Just imagine a jaw this size at the business end of a hungry shark. It's no wonder Megalodon could eat more than a ton of meat in one go.
Some of its relatives are the sharks we all recognize, but others evolved along a different track. Some even lost their teeth.
"These are stingrays, and here off the coast of the Cayman Islands, they gather in huge numbers to feed. Ah, haha, pretty enthusiastically as well. Easy now, boys."
Rays are sharks' cousins, but their body plan has flattened out to make the most of life on the seabed.
"They are absolutely incredible-looking creatures, and the way they move is really really beautiful."
These rays eat fish. And they know I've got a juicy morsel in my hand.
"You have to be a little bit careful when you're feeding them, because that mouth has a nasty suck on it. They don't have much in the way of teeth, but they’ve got this bony plate that acts as a grinder, and it can grind your fingers as well as I've found out"
These rays usually hunt crabs and fish that they can detect hidden in the sand.
"They get very very friendly when you don't feed them,wow,ok,easy, petal."
Stingrays have an array of fine-tuned senses. It's something all the shark family have taken to a whole new level. And to show you how good they've become, I'm going to run a little experiment. This should do the trick."
In the open ocean, surprisingly, sound is usually the first cue that alerts a predator to a potential meal. It travels four times faster in water than in air. |
