Shark’s livers contain lots of oil, called squalene, which helps them maintain their buoyancy in the water. Image (c) Dutch Shark Society
Sharks only have inner ears (which is why we can’t see them). Image (c) HowStuffWorks
In certain conditions female sharks can give birth without mating with a male- this is called parthenogenesis and involves the creation of an embryo through external fertilization.
One can tell the difference between a male and female by checking whether or not they have claspers; claspers are modified pelvic fins only found on male sharks, which are used to channel semen into the female’s cloaca during mating. Image (c) Patrick Cooney
Squalene is rich in vitamin C, and during World War II sharks were killed by their thousands to supply troops with vitamin C whilst out in the field.
Bronze whalers are called this because of the bronze coloured ridge they have between their dorsal fins. They are also known as copper sharks. Image (c) Rudie Kuiter
An average great white shark needs to eat the equivalent of one baby seal every three days to fulfill its energy requirements. Image (c) Dave van Beuningen
Whale sharks are the largest fish in the sea and can grow up to 14 meters in length while the smallest shark in the ocean, the dwarf lantern shark (pictured here), is only 20cm long. Great white sharks can grow up to 6 meters in length. Image (c) Chip Clark
The fastest shark in the ocean is the shortfin mako shark which can swim up to 100km per hour. Image (c) jidanchaomian.
Cookie cutter sharks only grow to be about 50cm long and while this prevents them from being predatory sharks, their fearsome teeth enable them to rip out chunks of flesh from larger marine species. Image (c) Sharkdivers Blogspot
Some species of shark (e.g. Great Whites) cannot survive if they stop moving because they don’t have the necessary muscles to pump water through their mouth and over their gills, but as long as they keep swimming, the water moves over their gills and keeps them alive. This is known as ram ventilation.
Sharks have been around for over 400 million years and have barely changed shape since then.
Sharks have between 5 and 7 gill slits on the sides of their heads.
Sharks have the same five senses we do – sight, smell, taste, hearing and touch. However they are also able to detect pressure waves in the water from struggling fish. These waves are picked up by their lateral line, a thin line which runs down the length of the shark and is filled with small pressure sensors which helps them detect the movement and direction of an object. They also have the ability to detect the electromagnetic fields emitted by their prey (their electrical sensors are called ampullae of Lorenzini). Image (c) Shark Shield
Most sharks hunt at night or during the evening. Sharks have different hunting strategies e.g. great white sharks attack their prey from below, while species that live on the ocean floor will bottom-feed. Some sharks attack schooling fish e.g. thresher sharks, and others swim through the ocean with open mouths, filtering plankton and krill, e.g. whale sharks.
Most shark species live for 20-30 years but some, such as the spiny dog fish and whale shark, can live for over 100. The maximum recorded age of a great white shark is approximately 70 years old. The age of a shark is determined by the number of rings in their vertebrae, where one year of grow equals one ring, much like the rings in a tree. Image (c) Canadian Shark Research Lab.
Sharks have no bones, their skeletons are made up of cartilage. Cartilage is more flexible than bone which helps the shark with agility as well as saving energy. When a shark dies the cartilage skeleton quickly deteriorates and only its teeth are left behind. Image (c) Canadian Shark Research Lab.
Ragged tooth sharks are the only sharks known to swim to the surface and take in air; this air is stored in their stomachs and allows them to float motionless while looking for prey. Image (c) Howard Hall
Ragged tooth sharks engage in two forms of intrauterine cannibalism; the first one involves the consumption of smaller, weaker embryo’s by the strongest one. This continues until there are only two developing embryo’s in the mothers uterus, one on either side, which enables them to grow much larger than they would have had they been sharing their food and space with multiple siblings. Oophagy is the other form of cannibalism that ragged tooth sharks participate in while in the womb and occurs when the developing embryos eat the mother’s unfertilized eggs. Image (c) Renee Blundon
