SHARKS ANATOMY SHARK SENSES SHARK TEETH REPRODUCTION
On this site I will attempt to give you some information on a few sharks found around the coasts of our country. These will be the ( Mako, Great White, Tiger, Thresher, Blue, Bronze Whaler, Hammerhead, the Sand, and the Basking ,shark). maybe at a later stage I will add some more.
But in reality there are actually more than 400 different shark species alive today, and they vary considerably in size and appearance. In fact did you know that roughly 50 percent of the shark species are less than a meter long.
GENERAL FACTS
In fact sharks all around the world come in all shapes and sizes. One of the smallest sharks is called the spined pigmy, this shark is only 150cm or 6" long when fully grown.
The largest shark in the world is called the whale shark, This shark only feeds on plankton but can grow to more than 40' long. Sharks are mostly found in the warmer waters, they are large, fierce fish, that usually eat animals. They usually live in the surface waters of the sea.
Sharks are versatile, fast swimming, and keen-sensed fish, many species of which are able to hunt and eat nearly all the larger marine animals in both shallow and deep seas.When they swim close to the top or surface you may see their dorsal fin sticking up out of the water.
Most sharks are grey in colour and have leathery skin covered with small, sharp, pointed (tooth-like) scales.
Sharks usually have five to seven gill slits that lie just behind the head.
Sharks have large mouths on the underside of their heads, and may have several rows of sharp teeth in the mouth. These teeth can bite through almost anything. These teeth, which are frequently lost in the flesh of prey, are quickly replaced by other teeth that shift into position to replace the lost ones.
Sharks, to a large extent, are scavengers, eating injured fish, carrion, rubbish and other waste from ships, as well as animals such as seals, turtles, birds, whales, crabs, and a wide range of other fish. Some also prey on smaller sharks. They have also been known to attack and eat people (though this is very rare) and it is believed that they were mistaken for seal lions part of a sharks diet.
The sharks that are considerd the most dangerous to humans would be the great white shark, the hammerhead shark, the tiger shark, and the blue shark.
Sharks in general are solitary animals. They typically live and hunt by themselves, joining up with other sharks to form schools only in certain circumstances, such as mating and sometimes feeding.
Some camouflaged bottom dwelling sharks blend in with the ocean floor waiting for its prey. When a fish gets close enough the shark opens its mouth wide and swallows the fish whole.
Other sharks such as the Great white that hunt bigger animals proceed very cautiously when approaching their prey.
Once it has found a potential meal, the shark will circle at some distance sizing up the situation. When it is ready, the shark moves in quickly taking a large bite before the animal knows what's happening. Often this first attack is sufficient to bring down the prey.
As I stated earlier on rare occasions sharks will cooperate together in a hunt. When these sharks hunt for food like seals, they rely on strength in numbers much like a pack of wolves. One large fur seal is too big for a single shark to kill by itself so the sharks circle around a single seal and slowly move in closer and closer. When they get close enough one shark will suddenly attack and the rest will follow.
The highly active sharks tend to be shaped like a torpedo, but many less active sharks are smaller and flatter.
Sharks have two identical sets of fins on the sides of their body, in the same general position as the main wings and tail wings of a aeroplane.
The shark is able position these fins at different angles changing the path of the water moving around them.
When the shark tilts a fin up, the water flows so there is greater pressure below the fin than above it. This creates upward lift.
Much the same when the shark tilts the fin down, there is greater pressure above the fin than below it. This pushes the shark down.
The shark also has between one or two vertical dorsal fins on its back and sometimes a vertical anal fin on its underside. These fins work like the vertical stabilizer wing on an airplane. They help the shark keep its balance as it moves through the water and they can be moved from side to side so the shark is able to turn to the left or right.
This fin arrangement gives sharks amazing maneuverability.
Sharks can also swim very fast and stop suddenly, or make sharp turns in every direction. This is one of the reasons they are such effective hunters.
Most of the time they can move more quickly and with greater control than any of their prey. A lot of the time a shark's prey doesn't even know what hit them till it's too late.
Sharks are also very different in their habits and habitats.
They are not only found all over the world and at every ocean depth. The larger more active sharks tend to hunt in the surface areas of the ocean, while many of the smaller sharks stay near the ocean bottom.
Some sharks swim long distances every day, while others tend to stick to a small area.
Sharks also have a very unique skin texture. They don't have the large prominent scales found in the normal bony fish. Instead they're covered with smaller scales called (denticles) much like sandpaper.
These tough, protective denticles are aligned so that they channel water over the shark's body, minimizing drag due to friction.
Sharks breathe like other bony fish by extracting oxygen from water.
Most pelagic sharks extract oxygen using ram ventilation. The water enters through the mouth and passes through the gills and is expelled through gill slits behind the head. In bony fish these slits are covered, but in most sharks you can see them clearly.
As the water flows through the gill opening, it passes tiny gill filaments. These filaments are covered with microscopic blood vessel capillaries, which have a lower oxygen content than the water around them. This causes oxygen in the water to diffuse (disperse) into the shark's bloodstream, where it is distributed throughout the body.
These highly active sharks depend on ram ventilation almost entirely, which means they constantly stay in motion most of the time.
Some sharks have a gill pump. This is a set of muscles that suck in water and push it past the gills. This works something like our lungs. This type shark can continuously gather oxygen while it is in a still position.
One of the main reasons sharks are such effective predators is their keenly attuned senses.
Many people think that Sharks have and use their one and only keen sense of smell.
Sharks actually have several acute senses, and that they depend on all of them working together. When you take one away, it significantly restricts the shark's hunting ability.
The shark's nose and sense of smell is definitely one of its most impressive features.
As the shark swims, the water flows through the two nostrils positioned along the sides of the snout. This water enters the nasal passage and moves past folds of skin covered with sensory cells. In some sharks, these sensitive cells can detect even the slightest traces of blood in the water.
Some sharks eg: The great white is able to detect one drop of blood in an large swimming pool.
Infact most sharks can detect traces of blood from many miles away.
Another amazing thing about a shark's sense of smell is that it is directional, this is to say that a shark can figure out where a smell is coming from and head in that direction.
Another shark sense is the eyes. This eyesight varies from species to species. Sharks that stay and live at the bottom of the ocean have very large eyes that let them see in almost complete darkness. At the same time some less active sharks that stay near the surface don't have particularly acute eyesight.
Almost all sharks have a fairly wide field of view however since their eyes are positioned on each side of the head.The Hammerhead shark is an extreme example of this because it's eyes actually protrude out from the head.
Sharks also have a very acute sense of hearing. Some researchers suggests they can hear low pitch sounds well below the range of human hearing. Sharks may detect and follow sounds over many miles of ocean. They seem to be able to listen specifically for distress sounds from wounded prey.
Another unique sense organ is the shark's lateral line. The lateral line is basically a set of tubes just under the shark's skin. The two main tubes run on both sides of the body, from the shark's head all the way to its tail.
Water flows into these main tubes through pores on the skin's surface. The insides of the main tubes are lined with hair-like protrusions, which are connected to sensory cells. When something comes near the shark, the water running through the lateral line moves back and forth. This stimulates the sensory cells, alerting the shark to any potential prey or predators in the area.
As I stated earlier in this section about the sharks senses. If you took one away it would significantly restrict the shark's hunting ability.
By themselves, none of a shark's sense organs would be adequate for effective hunting. But the combination of all these senses make the shark a most efficient predator.
Apart from the Whale and Basking shark that do not have teeth, Sharks are carnivores and these sharks have teeth suited only for eating flesh.
The teeth in sharks are very sharp and pointed.
Many sharks have combinations of long pointed teeth and wider serrated teeth, so they can hold their prey in place while they cut into it.
Other sharks have wide serrated teeth. These teeth act something like a hunting knife biting off large pieces of flesh and easily cut through flesh and bone.
In most fish and animals the lower jaw moves, and the upper jaw is firmly attached to the skull. In sharks however the upper jaw rests below the skull and can be detached when the shark attacks its prey. This lets the shark thrust its entire mouth forward to grab onto its prey.
This is a very unique jaw structure that makes a sharks mouth an especially effective weapons.
The sharks teeth are attached to the jaw by soft tissue and they are constantly falling out all the time. This is crucial to the shark's effectiveness because the worn and or broken teeth are continually being replaced by new sharp teeth.
In some sharks, such as the great white, these teeth are arranged in several rows.
Sharks only mate occasionally and give birth to a small number of young at a time. These young are called litters, and the individual young called pups (just like dogs)
Female sharks are extremely particular about choosing a mate, and males may have to contend with tough competition. This helps ensure that the young will be fit and healthy.
The birthing process varies from species to species. Some sharks lay eggs in protected areas on the ocean floor. When the young shark is fully developed, it breaks through the tough egg casing and heads out on its own.
However most shark species the young shark develop inside the womb and are fully formed at birth like us humans. These shark young typically look like adult sharks,but only much smaller.