Sharks are different with other fishes
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Sharks and rays do not have true bones like other fishes. They have cartilage instead which is lighter and much more elastic and allows them to bend in very tight circles.
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Sharks do not have swim bladders. A swim bladder is a gas filled sack inside the body of bony fishes that allows them to stay still without sinking. Sharks compensate by having a very big liver that is filled with oil. Even so, sharks sink unless they keep swimming forward. The exception is the Sandtiger Shark which swallows air to make itself more buoyant.
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A shark’s upper jaw is not fused to its skull like most animals. When a shark bites a large object, it is able to move its upper and lower jaw forward in order to take a bigger bite.
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Unlike other fishes, sharks are able to replace their teeth constantly. New teeth grow from the inner surface of the jaw and rotate forward when the old teeth get worn out or lost during feeding.
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Sharks and rays do not reproduce like other fishes. Most fish release clouds of sperm and eggs into the water column where they mix together. The fertilized eggs then float around until the fish larvae hatch and form schools of tiny fish. Male sharks have two organs called claspers attached to their anal fins. They insert one of these into the female shark’s cloaca (the entrance to the uterus) to transfer sperm (just like in mammals). Some sharks and rays incubate the eggs in their uteruses until the baby sharks are ready to be born. Other sharks and rays (i.e. skates) lay eggs and attach them to the reef.
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Sharks have between 5 and 7 gill slits on each side of their body in front of their pectoral fins. Bony fishes only have one pair. Having many exposed gill slits probably helps transfer more oxygen into their blood faster which allows them to swim very fast when they need to.
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Most shark’s skin is covered in small denticles instead of scales. Denticles are a lot like teeth. They have dentine in the centre and enamel on the surface. This makes shark’s skin very tough and abrasive like sandpaper. The shape and position of some shark’s denticles also helps reduce friction so that they can slip through the water easier.
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Sharks have an extra sense that is able to detect tiny electric fields. They can use this to find food that is buried or to search for animals to eat in the dark or in turbid water.
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Sharks and rays make up the sub-class of fishes called elasmobranches. This sub-class is part of a class of cartilaginous fishes called Chondrichthyes which also includes chimaeras (ratfishes).
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Shark Alliance
The Shark Alliance was formed in 2006 in an attempt to streamline the efforts of NGOs involved in shark conservation. The Alliance is able to utilize the manpower, resources, and combined knowledge of its member organizations to more effectively lobby for sustainable European and global shark fishing limits. Members of the Shark Alliance include The Shark Trust, the European Elasmobranch Association, and The Ocean Concervancy, among others.
In its own words:
The Shark Alliance is a not-for-profit coalition of non-governmental organizations dedicated to restoring and conserving shark populations by improving European fishing policy. Because of the influence of Europe in global fisheries and the importance of sharks in ocean ecosystems, these efforts have the potential to enhance the health of the marine environment in Europe and around the world.
The mission of the Shark Alliance is two-fold: To close loopholes in European policy regarding the wasteful and unsustainable practice of shark finning; To secure responsible, science-based shark fishing limits for long-term sustainability and ecosystem health.
Sharks have evolved over 400 million years and play a critical role in ocean ecosystems. In common with land predators such as lions and wolves, sharks keep other marine populations in check and help maintain the balance of life in the sea. Today, primarily because of overfishing sharks are among the oceans’ most threatened animals. Tens of millions of sharks are killed each year, either intentionally or as bycatch in commercial and recreational fisheries. Ongoing assessment of the status of European sharks (and closely-related rays) by the IUCN (The World Conservation Union) has led to the classification of roughly one third of evaluated species as threatened (either Critically Endangered, Endangered or Vulnerable), with another 16 per cent at risk of becoming so in the near future. Sharks generally grow slowly, mature late and produce few young. Shark populations are therefore especially vulnerable to overexploitation and slow to recover once depleted. The loss of these important predators is predicted to have negative effects on many other species in the sea. Unfortunately, however, misinformation and fear all too often impede the public support required to ensure sharks receive management priority and conservation actions. Unlike many countries that fail to conserve sharks, Europe does not lack the resources to restrict fishing. Despite immediate threats facing sharks there are few European limits on shark fishing, and quotas are routinely set far in excess of actual catches. In 2003, the EU adopted a ban on shark finning (the wasteful practice of slicing off a shark’s fins and discarding the carcass at sea), but at the same time allowed glaring loopholes that render the ban all but meaningless. For instance, shark fishermen are allowed to land shark carcasses and fins separately, making it all but impossible to tell how many sharks have been processed on board and how many were subjected to shark finning. Meanwhile, the fin to carcass ratio (the means of checking that the number of fins corresponds to the number of carcasses – after sea processing – is within the ban’s limits) is the highest and therefore the most lenient in the world. Europe is home to the some of the world’s largest fishing fleets while its powerful fisheries officials exert influence on international fishing restrictions in many regions of the globe. Poor European shark policies, therefore, pose threats not only to shark populations in European waters but also to those around the world. If fisheries are managed carefully, sharks can provide a steady source of food and recreation and help keep the oceans in balance. The Shark Alliance is dedicated to ensuring that these valuable yet vulnerable animals survive and thrive for the benefit of ocean ecosystems and the people that depend on them. Save buying products with payday loan
