FACT SHEET 14
SHARKS
• Sharks have a skeleton made of cartilage (like humans’ ears and noses), which makes them lithe and agile.
• Fish-eating sharks (such as tiger sharks) have rows of razor sharp teeth which they use to tear flesh from their prey whilst sharks that eat crabs and other animals living on the seafloor (such as port jackson sharks) have hard crushing plates to break tough shells. Some small shark species are prey to larger fish and sharks.
• Sharks remove weak, injured or diseased animals from the food chain, and by doing so help maintain healthy ecosystems. They also control the over abundance of certain species. Their role is vital to the reef as they are the apex predators in the food chain.
• The whale shark (a shark not a whale) is the biggest fish in the world, but eats small marine animals and is harmless to humans.
• Humans use sharks in many ways. The practice of shark finning, where sharks are stripped of their fins and left to drown, is common in some countries. The shark fins are then made into a shark fin soup, which is seen as a delicacy. Some have called the practice brutal and it is seen as a primary contributing factor to the sharp decline of some shark species.
• Sharks are caught in nets and lines, and in some beach areas shark buoys attract and kill sharks in order to protect swimmers.
• Shark meat, also known as flake, is the main fish used in fish and chips in Aussie shops. This is not always advertised in the shops. Many shops do offer alternatives however, such as barramundi and cod, which are a more sustainable choice.
• Sharks are now one of the most threatened groups of fish in Australia, as they are slow to reproduce and not able to replenish their stocks quickly enough. Up to one hundred million sharks per year are killed around the world.
• Sharks have been around for 400 million years and are a keystone species in the marine ecosystem (keeping the delicate balance in check). Their decline could also have a catastrophic effect on the marine environment.
Interesting fact: The Gray Nurse Shark has two wombs in which several young grow, eating each other until the two (one from each womb) survivors are born. This process takes up to two years.
Further links:
• ReefED: http://www.reefed.edu.au/home/explorer/animals/marine_vertebrates/sharks_and_rays
• Australian Museum online: http://www.amonline.net.au/fishes/fishfacts/fish/cmelanop.htm
• Shark Research Institute: http://www.sharks.org/
• Kidzone: http://www.kidzone.ws/sharks/index.htm
• Florida Museum of Natural History: http://www.flmnh.ufl.edu/fish/
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