Sharks - FAQ's2013
By Amelia Meyer
By Amelia Meyer
1. Are shark fish?
Yes. Sharks live underwater and breathe through gills. They are generally considered to be cold-blooded.
2. What are the largest and smallest sharks in the world?
The biggest living shark is the Whale Shark, which is over 45 feet, or almost 14 metres, long! Despite being so huge, this shark is harmless to humans as its diet consists solely of plankton and the tiny fish that can get through the feeding sieve in its mammoth mouth. The smallest shark is the Spined Pygmy Shark, which reaches an average length of less than 10 inches, or 25.4 centimetres. This little specimen lived in the deep waters and glows in the darkness of that depth!
3.Are all sharks cold-blooded?
Most sharks are technically cold-blooded, or ectothermic. This means that the temperature of their body depends entirely on the temperature of the water around them. But, there are some exceptions to this rule. For example, the Great White Shark controls its body temperature internally, and maintains a warmer temperature than that of its environment. This makes it somewhat warm-blooded, despite not being a true endotherm.
4.Are sharks just eating machines?
Sharks actually eat slightly less than human beings do in terms of percentage compared to their body weight and size. Their livers are filled with oil that is rich in nutrients and vitamins. In times of great shortage, the shark can live for many months without eating, gaining energy solely from this oil. In addition, most shark species are prone to sticking to one type of food, and are prepared to look for that food rather than eating whatever is more easily available.
5.How fast do sharks swim?
The speed that a shark can reach depends very much on what type of shark it is. Most species cruise at a slow speed of about nine kilometres an hour. They only speed up when they are in pursuit of prey, as this uses up much of their energy. Some sharks can reach up to 50 kilometres an hour and there have been unconfirmed reports of tracking a shark at nearly 100 kilometres an hour.
6.How long have sharks been around?
According to dental remains of ancient sharks, they are believed to have swum this planet's oceans some 400 million years ago. It is difficult to confirm this as the cartilaginous skeleton decomposes upon death, unlike bone, which can stay preserved under optimal conditions for millennia. So, teeth are the only remnants of these now-extinct species.
7.How do sharks communicate with one another?
Sharks use their body language to convey messages to one another. For example, when issuing a warning, the shark will hunch its back and swim with overly-pronounced movements. Surfers and divers that have been attacked have also reported this behaviour prior to the attack.
8.Do sharks get sick?
Sharks can get bacterial infections, parasites (e.g. tapeworm), liver disease, cancer, meningitis, and even leech and lice infestations.