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There are more than 500 species of sharks swimming in the oceans today, which are split across eight orders: Carcharhiniformes; Hederodotiformes; Hexanchiformes; Lamniformes; Orectolobiformes; Pristiophoriformes; Squaliformes; and Squatiniformes. Each has unique characteristics and behaviours. As sharks continue to be studied, we are learning more and more about the critical role they may play in ocean ecosystems.
Crucially for seagrass and coral reef habitats, they help to regulate the populations of other predatory fish, like groupers, who would otherwise exist in abundance, and feed on the herbivores who feed on the macroalgae. With fewer herbivores, macroalgae would expand and overpower the coral, affecting the health and survival of the reef system.
One study also found that seagrass ecosystems without sharks were less resilient to climate change, and it is likely that sharks play similar roles worldwide. Healthy shark populations also support communities whose livelihoods depend on local shark species for food and ecotourism.
Amazing predators, sharks have evolved over thousands of years to become one of the most powerful creatures in the sea. Keep reading to discover interesting facts about sharks.
The scientific name for all sharks and rays is Elasmobranchii, but each species of sharks and rays also has its own scientific name.
Many species of shark are classified as endangered or threatened due to slow reproduction rates, habitat loss, and overfishing.
Approximately 50% of shark species are threatened or near threatened with extinction. Pelagic sharks (species of sharks found on the high seas) have declined by 71% in the past 50 years alone, while the whale shark, goblin shark, basking shark, hammerhead shark, and tiger shark are just a few examples of endangered sharks listed on the IUCN Red List of Threatened Species.
Risks to sharks and rays include habitat loss, pollution, and overfishing. They also have slow reproduction rates, which means that it takes time for decreasing populations to recover.
The exact number of sharks killed each year is uncertain, but estimates range up to 273 million.
More than 100 million sharks are killed in commercial fisheries each year—about twice what scientists estimate to be sustainable.
Shark habitats are as varied as sharks themselves. So the answer to the question “where do sharks live?” is simply: in water.
Some shark species (such as the great white shark) prefer cooler waters, while others (like the whale shark) prefer warmer waters. Some sharks (like the bull shark) are even able to live in both saltwater and freshwater environments. You’ll find sharks in many types of bodies of water, including:
All known sharks either have a carnivorous diet, meaning they mostly eat larger marine animals, or a planktivorous diet, meaning they feed primarily on tiny species of plankton. Planktivores (including the megamouth shark, whale shark, and basking shark) feed on planktonic food, such as zooplankton and phytoplankton. Carnivores (all other sharks) eat anything from small fish, squid, and turtles, all the way up to seals and other sharks, depending on their size.
Sharks face a range of threats, including overfishing, habitat loss, climate change, and pollution, which are putting many species at risk of extinction.
Shark finning involves catching sharks, removing their fins while they are still alive, and discarding the rest of the animal back into the ocean where it often dies a slow and painful death.
The demand for shark fins has increased in recent years due to their high monetary and cultural value, leading to an estimated 23 to 73 million sharks being finned each year.
While many countries have implemented regulations to limit or ban shark finning, enforcement remains a challenge.
Bycatch refers to the unintentional capture of non-target species, including sharks, during fishing operations. Bycatch poses a significant threat to sharks, as they may be caught in large numbers and discarded, injured, or killed. Bycatch can also impact the wider marine ecosystem by disrupting the balance of predator and prey species.
Overfishing, climate change, pollution, and habitat destruction are among the most significant threats to ocean health. Climate change is a particularly major concern, as rising sea temperatures and ocean acidification can have significant impacts on the survival and reproduction of many shark species. Pollution and habitat destruction has already hampered the availability of food and shelter for sharks, making it even more difficult for them to survive and reproduce.
To make matters worse, sharks have a very slow life history. Slow growing and late to mature, some shark species only produce a handful of pups every two to three years and their populations are very sensitive to overfishing. When overfished in such high numbers, the damage inflicted can result in populations taking decades to recover.
No, sharks are not mammals. They are actually a type of fish. Unlike mammals, sharks don’t grow hair, produce milk, or have a neocortex (part of the brain involved in perception and thought, among other things). Instead, like other fish, sharks have gills, are cold-blooded and are covered in denticles (tooth-like scales).
Technically not. Sharks do have a skeletal structure, but it is made of cartilage, which is a flexible and durable tissue that helps sharks maneuver in the water and minimises the energy they need to spend while swimming. It’s a bit like the material found in our ears and noses.
Until recently, it was thought that sharks did not sleep in the same way that humans or other animals do. They had only ever been observed resting on the ocean floor or in caves, or swimming at a slower pace to conserve energy. Interestingly, though, a one study found that some sharks (like New Zealand’s draughtsboard shark) have muscles in their mouths that pump water over their gills, allowing them to breathe while resting, meaning they do in fact fall asleep during their resting periods–sometimes with their eyes open.
While many sharks give birth to live offspring, some species of sharks do in fact lay eggs (they’re often referred to as a “mermaid purse”). These are known as oviparous sharks.
The number of teeth that sharks have varies depending on the species. However, most sharks have multiple rows of teeth which are continuously shed and replaced throughout their lives.
Great white sharks have as few as 50 teeth, while whale sharks have the highest tooth count with 3,000 tiny, pointed teeth.
On average, most sharks live between 20 and 30 years, although some can live much longer. The Greenland shark, for example, can live at least 272 years, and is one of the longest-lived vertebrates (backboned animals) in existence.
IFAW is working to reduce the global mortality of sharks and rays by putting limits into place to manage the trade and catch that is driving shark declines worldwide,
For over a decade, we have partnered with member countries of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), to achieve limitations on the trade in threatened shark species—ensuring any continued trade is legally and sustainably sourced (this is known as an Appendix II listing of the Convention).
Listed species are provided robust regulation, monitoring, and enforcement of sustainable trade limits by governments all over the world. CITES management prioritizes the identification and seizures of illegal shipments of shark products, as well as driving better fisheries management at the national level—leading to effective reductions in shark and ray mortality worldwide.
IFAW also provides support to action on these regulations, such as identification and enforcement trainings, as well as the development of technical tools as governments seek to enact CITES listings for sharks and rays at home.
By focusing on sustainable trade limits for shark species, we hope these listings will provide a global framework to prevent the shark trade from driving species towards extinction, and individual countries can then make decisions on trade and fisheries based on the health of populations in their waters.
With support from our partners, IFAW advocates for sustainable trade limits for shark species threatened by the international demand for shark fins and provides resources and support to governments seeking to better manage sharks and rays in their region.
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