Shark

sharkSharks, like many predatory animals, tend to get a mixture of fear and admiration from people. On one level, people are terrified of them, on another they admire them for being strong, powerful creatures. Sharks do tend to be more towards the “feared” side though. It’s likely films such as Jaws have influenced this. Sharks are sometimes presented in a positive way, sometimes appearing in cartoon form on surfboards or tattoos, or as part of brands in general, in a “badass” sense. But is this perception accurate to how sharks behave in the natural world? This BBC documentary, narrated by Paul McGann, looked into that.

By far the most well known shark is the Great White Shark. This is deserved in a sense, as it is the most skilled. But there are in fact 520 different species of shark, coming in lots of shapes and sizes. What they all share in common is that they have cartilage rather than bones.

The Greenland shark survives incredibly tough conditions. It lives in the Arctic sea, which is frozen over and it is only the sea salt that prevents it from freezing solid. The temperature is still low, and very little can survive there, making it a barren, bleak place. The Greenland shark has to scavenge, and mainly land animals, polar bears which have drowned or reindeer which have died and fallen into the water. Most of the time, the Greenland shark finds nothing to eat. If that wasn’t hard enough, they also have the problem of copepod parasites, which feed on their eyeballs and eventually leave the Greenland shark blind, having to rely only on their, admittedly excellent, sense of smell. Not only does the Greenland shark survive hear, it lives for a very, very long time. 200 years to be exact. This is as a result of the low metabolism necessary to live in such a cold environment.

The Tip Reef shark has a sort of double life existence, depending on whether it’s day or night. It’s a bit like Jekyll & Hyde, or Dracula depending on your horror reference of choice. During the day they are very placid and just lay on the floor, tolerating fish using their rough skin as a scratching post and seals pestering them. But at night, everything changes. They terrorise the seabed in gangs, while other creatures run or hide away. This stops almost instantly as soon as the sun rises, and they go back to their daytime state. They choose to only hunt at night as they have an advantage of not needing sight so much, being able to detect electromagnetic fields of other fish, so better to save all their energy for times when they can use the darkness as another advantage and rest during the day.

The Mako shark was described in the narration as “a torpedo with teeth”, and it was shown to be faster than a speedboat. It has been recorded as being able to swim between 30-46 miles per hour, and it may even be able to swim faster than that.

A tiger shark’s jaws are powerful enough to crush a green sea turtles shell, which was one of the most violent sights in this documentary. It would be a mistake to view the tiger shark as a mindless, opportunistic killer. On the contrary, it is planned very far in advance. It traveled a long way to get to this spot and in fact timed its arrival exactly to coincide with the green turtles mating season.

Hammer head sharks are one of the better known species of shark, often shown in cartoons and comics as having a head literally shaped like a hammer. We saw a bit of the courtship of the scalloped hammerhead in this documentary. They all meet together with the females in the centre and the males on the outside. The males seek out the largest females, as they are more likely to breed successfully. For those that don’t manage to pair up, they have to come back the next day to try again.

The deep ocean is home to many of the most bizarre-looking creatures, and the frilled shark looks very much like it could be a mythological sea serpent. It looks like a snake with gills and fins, and rather like a snake it can open its mouth extremely wide to swallow its prey.

There were many astonishing sights filmed in this documentary, such as the ragged tooth shark swimming among shipwrecks. The ragged tooth shark gets its name aptly enough from having ragged teeth. It looks scary, though the film crew found that it was more scared of them. The ragged tooth shark’s basic design hasn’t changed in 400 million years, as it has served them well.

The goblin shark is another shark which has remained the same for a long time, in its case 100 million years. It uses its large snout to detect electromagnetic fields of fish, and its mouth extends out to catch the fish.

The Port Jackson shark was described as “older than the dinosaurs”. They lay corkscrew shaped eggs, which after laying them the mother hides under rocks. The strange shape is so predators won’t be able to get it from under the rock. The predator that most comes after these eggs actually looks very like the Port Jackson shark, but it is a different species, the crested horn shark.

Sharks eggs have colloquially been referred to as mermaid’s purses. The shark embryo is tiny compared to the egg at first. The reason the egg is so big is that it is filled with yolk. Some species take almost a year to hatch, but by the time they do all the egg yolk has been eaten, and the shark egg has shrunk.

Some sharks don’t lay eggs, and give birth to live young. The Lemon Shark carries 15 babies for a whole year! When she is ready to give birth, she goes to the same place she was born, to a mangrove swamps. As this is in shallow water, she has to leave quickly, and the baby sharks have to fend for themselves from then on. But they instinctively know they need to head up the river. We see the mangrove forest of the island of Bimini in the Bahamas. This was one of the most enchanting sights in the documentary, of an underwater forest with the cute baby sharks swimming between tree roots. They are reasonably safe here, as most predators can’t get in this is shallow water, and the roots provide somewhere to hide. They will stay here for seven years before heading out into the ocean.

Other sharks have evolved in unusual ways, and to many people won’t look like sharks at all. In the coral reefs of Indonesia (which look a bit like snow-covered trees from some angles!) is the Tasselled Wobbegong. It’s very well camouflaged, it’s skin looks like a stone and it has tassels which look like coral. It likes to hide in the entrance of a cave, so it can use it’s tail to look like a fish, giving real fish a false sense of security that the cave is safe. Then when a fish comes close, it springs out and eats it.

The epaulette shark of the Australian Great Barrier Reef is very small by shark standards, only two feet long. It has greenish-yellow skin with black spots, and its face is almost frog-like. It could easily be prey itself for larger sharks, so remains in hiding until the tide goes out. The larger sharks leave when they realise the tide is going out, leaving only shallow water and rock pools. Then the epaulette lives up to the “big fish in a small pond” saying, as it can have its pick of the other fish and has no predators. However, its moments as top dog… er, top fish, are short lived as soon the water will go out further, leaving only puddles, and the epaulette stranded on land. It has ways around this though. It will shut down all its organs so it won’t need to breath, and if all else fails it can use its fins to crawl on land until it can find deep enough water.

One thing I discovered in this documentary which surprised me was that rays are in fact sharks! They no longer look anything like other sharks, but they have all the same basic features, just stretched, with the fins looking like wings. On some rays, you can still see the dorsal fin on top.

We saw mobula rays, who look very graceful and elegant, almost balletic, ‘flying’ underwater. They can leap out over the surface of the ocean too, which reminded me a bit of the Batman signal.

Manta rays have the distinction of having the biggest brains of any fish. Like many animals, they can have symbiotic relationships with other creatures which feed on their parasites. Manta rays have no way at all of scratching themselves, so appreciate it when angel fish come and eat the parasites off.

An even more surprising example is the Grey Reef shark. They eat almost any fish they can find, but doing that causes bits of their food to get stuck in their teeth. That makes their teeth rot, and a shark with rotten teeth faces death by starvation. So the Grey Reef shark tilts its body sideways as a signal to fish that it won’t harm them and it wants its teeth cleaned! It allows fish to essentially give it a dentist checkup by swimming near it and eating the leftover food from its teeth. Wrasse fish are particularly daring, swimming right inside the shark’s mouth. The Grey Reef makes sure it never eats a wrasse, as they are far too valuable to lose.

Whale sharks are the biggest fish in the sea and are mostly filter feeders which eat plankton. But that isn’t a strict diet, they will eat fish now and again, and if they spot a fisherman’s net they’ll try to suck them out of there. Some fishermen have decided to feed the whale sharks directly, so that their nets don’t get damaged. It has been noticed that more and more whale sharks are coming each year, seeing it as an easy food source.

Indeed, sharks can hear their prey from long distances, and some have even come to associate the sound of fishing motor boats as “a dinner bell ringing”.

Things aren’t always good for sharks when it comes to fishermen though, in fact most of the time it’s bad. Some fishermen are of course fishing for sharks. Even if they aren’t, sharks can be injured accidentally, such as from taking fish from fisherman’s hooks. We saw the very sad sight of an oceanic white tip shark swimming with a fishing hook stuck in its mouth… and this shark was apparently one of the luckier ones. Many of the sharks which get caught on a fishing hook die, whether they were the intended catch or not. There’s also the fact that people are fishing in deeper depths than ever, with some shark species that haven’t even been discovered yet getting caught and dying in nets. Even though it is decreasing in popularity, shark fin soup is something which causes people to fish for sharks.

The great white sharks have their own territory, but they also respect each others space. It’s hard enough to find food, so if they can avoid using up energy and risking injury from a fight, they will. They communicate through body language. Arched back, fins showing and an open mouth signals that they don’t want to cause trouble, but the other shark should back off. They have been known to communicate this way to humans too,  we saw an example of this from the makers of this documentary, with a diver swimming outside a shark cage near a great white shark! Of course, they know exactly which sorts of shark are less likely to attack, which apparently are big females. They said that the females tend to be less aggressive, and bigger sharks in general are actually unlikely to attack humans, as with great white sharks the bigger ones tend to be more confident, and so will feel less threatened.

The final episode, showing how sharks are influencing science and technology was probably the weakest, but it had some interesting moments. One was scientists collecting whaleshark parasites using a tiny fishing net like you sometimes see pet shop workers get fish out of tanks. You can tell where the whaleshark has been from the parasites it has picked up on its journey, which was compared to “stamps on a passport”. There is also swimwear designed to mimic the texture of sharks skin, which proved to give so much of an advantage it ended up being banned from use in competitions.

The documentary showed many beautiful sights, such as the gorgeous blue ocean, and some remarkable footage of all the different kinds of sharks. I liked the use of metaphors in the narration to. I know that’s something few people would care about, but I appreciated it. I liked how the ocean was compared to a desert. You could not get two more different environments than an ocean and a desert, but they have similarities. They are both massive, hostile and often empty where you have to look very hard to find signs of life.

I never knew how fascinating sharks were, and how much variety there was to them. Sharks are definitely tough, and good hunters, but they are very rarely a threat to humans. They tend to not be interested in us, and focused more on their usual diet of fish or seals. If anything, they have more to fear from us. One things for sure, sharks are not the vicious, brutish, mindless killing machines they are often thought to be. They are actually quite intelligent and sophisticated. They can be vicious killers to their prey, but that is how predatory animals have to survive, and sharks don’t behave that way all the time. Sharks deserve more respect than we currently give them, but they are gaining in popularity, which is good.

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