Some sharks can change shape. Swell sharks inflate their bodies with water or air to make themselves bigger and rounder.
The insides of the sharksintestines are spiral shaped. Because of this, some sharks have spiral-shaped droppings.
Some sharks are so flexible, they can bend right around and touch their tails with their snouts.
Shark skin is so rough that in the past it was used to make a type of sandpaper, called shagreen.
Without their fins, sharks wouldn’t be able to stay the right way up. They’d roll over in the water.
Most sharks never close their eyes. Some have special see-through eyelids that protect their eyes without cutting out light. Others just roll their eyes up into their head to protect them.
Although sharks can hear sound, they rarely make a noise.
A shark can sense a turtle, octopus or other prey from up to 20m away.
In one experiment, a scientist plugged one of a shark's nostrils. It swam around in a circle.
Shark brains aren’t round like a human's; they are long and narrow.
If sharks don’t keep on swimming they sink to the seabed.
A typical shark has several hundred teeth at any one time.
Shark jaws are strong enough to bite a turtle in half.
In Australia in 1935, a tiger shark vomited up a human arm. The shark had not killed anyone but had scavenged the arm after a murder victim had been cut up with a knife and thrown into sea.
As a way to put off attackers (or to remove indigestible stomach content), sharks can turn their stomachs inside out and vomit up their latest meal. Some predators eat the vomit instead of the shark.
The electroreception in sharks is so sensitive that they often mistake the minute electrical charge caused by rusting boat hulls for prey.
The ancient Greek scientist and writer Aristotle studied and wrote about how sharks mate over 2300 years ago.
In sand tiger sharks and several other species, the biggest, strongest pups eat the others while still inside their mother’s body.
Sharks never stop growing; when they reach adulthood, they just slow down.
Epaulette sharks are often found in rock pools. They can move from one pool to another across dry land, by dragging themselves with their strong pectoral fins.
A whale shark's skin is around 10 cm thick, making it the thickest skin in the world.
In 2004, while snorkelling in Australia, Luke Tresoglavic was bitten by a small wobbegong that refused to let go. He had to swim to the shore and drive to get help with the shark still attached to his leg.
You have a greater chance of being struck by lightning, drowning in a bathtub, fatally falling down stairs, or dying from a bee sting than being killed by a shark.
Sharks have been around longer than trees!
Until the late 16th century sharks were usually referred to in the English language as sea-dogs. The name "Shark" first came into use around the late 1560s to refer to the large sharks of the Caribbean Sea.
Some sharks, if inverted, enter a natural state of temporary paralysis called tonic immobility. Researchers use this condition for handling sharks safely.
The name shark may have originated from the Mayan word for shark, xoc, pronounced "shock" or "shawk".
The teeth of carnivorous sharks are not attached to the jaw, but embedded in their flesh. In many species, teeth are constantly replaced throughout the shark's life.
Even though the basking shark is considered to be slow and very large, it can actually breach the water, i.e. jump fully out, as some whales do.
Despite the common myth that sharks are largely instinct-driven "eating machines", recent studies have indicated that many species possess powerful problem-solving skills, social complexity and curiosity.
That sharks are not known to bite humans as often as people think.
The sea otter often keeps a stone tool in its armpit pouch.
...that the Southern Right Whale got its name because it was the ‘right’ whale to kill? Because they swim slowly, close to the shore and float when killed, the whalers thought them the right whales to kill!
...most whales and dolphins live long lives. Wild bottlenose dolphins live well into their forties, while some of the larger whales live in excess of 80 years!
...whale and dolphin mothers ‘suckle’ their young underwater! Mothers have muscular mammary glands and ‘squirt’ their milk into the calf’s mouth, to ensure that the calf takes in as much of the energy rich milk as possible.
...newborn cetacean calves ‘suckle’ three to four times each hour and will suckle from their mothers for six months or more.
...dolphins often leap clear of the water when travelling at speed. This is because the density of water is much greater than that of air and they are able to travel faster by leaping out of the water.
...on average, a whale or dolphin will eat four to five percent of its body weight in food per day. That means that a 100 ton blue whale will eat almost five tons of krill per day, or that a 200kg bottlenose dolphin will eat 10kg of fish per day!
...because whales and dolphins are streamlined to swim in water, they do not have external organs. This makes it almost impossible to tell the sex of a whale or dolphin when watching them on the sea surface.
...whales and dolphins don’t sleep in the way humans do. Although we don’t know how they sleep, some scientists believe they sleep with half the brain asleep and half the brain awake, keeping them aware of danger.
...there are probably types of cetaceans that are as yet unknown. For example, the Longman's beaked whale is only known from skulls washed ashore in Somalia and Australia. It has never been seen alive!
...all whales and dolphins have the remains of the pelvis, but it is reduced to two small bones at the rear of the animal.
...the ‘strapped toothed’ whale is so called because in mature males there are only two teeth in the bottom jaw and these completely ‘strap’ the upper jaw, preventing it from opening more than a few centimetres. How these animals eat is unknown, but it may be that they stun their prey with high intensity sound.
...some cetaceans can dive to depths of more than a kilometre and stay there for more than an hour.
...in baleen whales females are bigger than males, while in the toothed whales the males are bigger than females.
...common dolphins, which are often seen off South Africa’s east coast, can occur in schools of several thousand. The biggest school on record was estimated to consist of about 15,000 dolphins!
...when southern right whale and humpback whalesbreach (leap out of the water), seagulls can often be seen darting in to pick up pieces of skin that become dislodged from the breaching whales. Presumably this is an easy source of food for seagulls.
...newborn cetacean calves do not have the skills to swim for long periods or to accelerate away from danger, so they swim in the slipstream of their mothers, enabling the mother to protect her calf.
...the Orca, is the fastest swimmer of all the cetaceans and can reach speeds of more than 50km/h while hunting.
...all cetaceans have a blubber layer — a layer of fat under the skin. In most dolphins, this layer is about one quarter to one third of the total body weight, but in southern right whales nearly half of its weight (up to 50 tons) will be blubber.
...the Blue Whale has the largest penis of any animal on earth, estimated at over 2 m (more than 6½ feet)
...the Humpback Whales song is produced by them forcing air through their massive nasal cavities
...baleen from the Mysticeti whales mouths was used to stiffen parts of women's stays and dresses, like corsets
...the Sperm Whale was named after the milky-white substance spermaceti found in its head and originally mistaken for sperm.
...the Beluga Whale's milkfat is so high, the calf gains up to 2 kilograms per day on the diet. It is so fatty that the colour is green.
...the songs of whales were sent into space aboard the Voyager spacecraft to represent sounds from Planet Earth.
...the Beluga whale is also known as the Sea Canary on account of its high-pitched squeaks, squeals, and whistles.
...the Sperm Whale, at 18 metres long, is the largest toothed animal to have ever lived.
...in spite of their enormous mass, baleen whales are capable of leaping completely out of the water, particularly the Humpback Whale.
...the male narwhal's tusk can be up to 3 metres in length and weigh up to 10 kilograms.
...observations of cetaceans date back to at least the classical period in Greece, when fisherpeople made notches on the dorsal fins of dolphinss entangled in nets in order to tell them apart years later.
...groups of bottlenose dolphinss around the Australian Pacific have displayed basic tool use by wrapping pieces of sponge around their beaks to prevent abrasions. This is a display of a cognitive process similar to that of great apess.
...Qi Qi was the name of one of several captive Baijis held at the Wuhan Institute in China in an attempt to rescue the species.
...the Beaked whales (genus Ziphidae) contain over twenty species of small whales, and are the least known of all cetaceans.
...The ear bone called the hammer (malleus) in cetaceans is fused to the walls of the bone cavity where the ear bones are, making hearing in air nearly impossible. Instead sound is transmitted through their jaws and skull bones.
...cetaceans with pointed beaks have good binocular vision, but others, such as the Sperm Whale cannot see directly in front or behind.
