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A porbeagle shark (Lamna nasus) belongs to the family of mackerel sharks, and is noted for a white patch on its first dorsal fin. Located in the cool waters of the North Atlantic and southern hemisphere, the stocky shark is bluish gray on top and white underneath. It has a pointed snout, and it typically grows up to 12 feet (about 3.7 meters) in length and weighs up to 500 pounds (about 230 kilograms). The shark, which needs to swim constantly in order to breathe, has a life span of approximately 30 to 40 years and typically poses little danger to humans.
The shark can be found in a variety of locations across the globe, including in the Newfoundland Grand Banks and the Mediterranean Sea. In the southern hemisphere, porbeagles reside in coastal waters of Chile, Brazil, South Africa, Australia, and New Zealand. Typically, a porbeagle shark lives in water at depths of 1,120 feet (about 370 meters) in the open ocean. These waters are usually below 57 degrees Fahrenheit (about 14 degrees Celsius). To survive in cool ocean waters, porbeagle sharks have an internal heating regulatory system that boosts their body temperature as much as 18 degrees Fahrenheit (about 10 degrees Celsius) higher than the water temperature. This bodily adjustment allows a porbeagle shark to be a fast-moving predator.
The porbeagle shark has relatively large, sharp teeth with smaller versions of teeth on both sides of the bigger teeth. The shark typically preys on herring, mackerel, and lancetfish during the spring, and cod, flounders, and hakes in the fall. The diet of the porabeagle shark also includes squid and shellfish. Being substantial in size, the shark has no known predators.
After an eight or nine month gestation period, female sharks give birth to live young typically in the later winter and spring. Litter size may vary from one to six, but usually a female will give birth to four pups at a time. In the womb, the embryos have no placenta, and feed on yolk-filled eggs ovulated by the mother late in the gestation period. At birth, the pups are a little more than 2 feet (about 80 centimeters) long. Females are capable of giving birth around the age of 12, while males are sexually mature at the age of 7.
In most areas, the porbeagle shark is considered a near threatened species. In waters along the United States, the shark is a protected species. Canada also limits the number of fishing licenses for the shark and many European nations also regulate catches of the creature. In the southern hemisphere, there are no regulations against catching the shark, except in New Zealand. The shark is used by humans in oil products and fertilizer. Also, the fins of the creature are used to make shark-fin soup.