Pelagic sharks, also known as oceanic sharks, dwell in the open waters of the seas and oceans. They live in tropical and temperate seas, and many of them migrate. Pelagic sharks are continuously on the move and rely on buoyancy from the low density oils in their huge livers to keep them from sinking.
Benthic sharks live on the bottom of the sea, near shorelines. They may bury themselves in the sand to sleep or hide from predators, but they cannot swim out into deeper water like pelagic sharks. Some benthic species, such as wobbegongs, stay close to the surface even when not in danger because it is easier to escape by jumping into the water than it is to turn around and flee down below deck. Others, like guitarfish, spend most of their time deep under the surface of the water.
Sharks differ from other fish because they have teeth at the end of a jawbone. These teeth are arranged in pairs at either side of the mouth, with some exceptions such as the fangless shark. Each pair of teeth is covered by a horny plate called a denticle. The upper and lower jaws slide past one another when eating or fighting, which helps protect both parties from being bitten.
The word "shark" comes from the Portuguese esculenta, meaning "shell". This refers to the hard outer layer of some mollusks.
There are around 500 shark species swimming in the world's waters. They may be found in almost every ocean habitat, including the deep sea, open ocean, coral reefs, and under Arctic ice. Some species are commercially important while others risk becoming endangered due to loss of habitat or overfishing.
Sharks are related to fish but not all fish are sharks. Sharks have a body shape that is unique among vertebrates: they have a dorsal (top) surface and a ventral (belly) surface. Other fish have flesh only on one side. Sharks are also unique in that they lack bones inside their bodies; all their bones are outside their body, attached to external cartilage plates. This is why there are no skeletons inside a shark's body; any soft tissue could be damaged or even eaten if it got inside the mouth of the shark!
Sharks are often divided up into seven different families by scientists. These families include hammerheads, tiger sharks, bull sharks, lemon sharks, guitar sharks, and cookie-cutter sharks. Although these names give an idea of how these sharks look like, within each family there are many different species so they cannot be used as indicators of where to go fishing or not!
Sharks do exist in the oceans near Northern Ireland, contrary to common assumption. In fact, we have almost 20 different species! Discover Northern Ireland's sharks, skates, and rays below.
There are three main groups of shark: cartilaginous, bony, and electric. Sharks within each of these groups can be further divided into subgroups. For example, there are over 250 types of cartilaginous fish alone. Sharks are important for a number of reasons including their relationship with other organisms, their impact on human culture, and even as a food source.
In general, sharks are good at avoiding humans, which is why there are so few reports of attacks. However, this doesn't mean that you should go swimming with them or take them out for fun! There are several factors that may cause a shark to attack, such as feeling threatened, searching for food, or even following a female looking for a mate. Although very rare, if a shark does attack, its teeth can still be found in bodies of water where they've been caught. This usually happens when a person gets bitten but isn't killed by the shark; instead, they escape while the shark continues to look for more victims.
It is important to understand that not all sharks are equal when it comes to threat.