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The Porbeagle Shark is also known as mackerel shark.
Scientific name........Lamna Nasus
Other Common name..........Mackerel shark
The Porbeagle and its North Pacific relative, the Salmon shark are the smallest of the five mackerel sharks. These sharks have a stout torpedo shaped body, pointed snout and two keels on the tail. The Porbeagle and Salmon sharks are the only sharks with a secondary keel at the base of their crescent-shaped tails. This efficiently cuts the water in its side-to-side swimming movement. There is no white patch above the pectoral fin, but a very distinctive white free rear tip to the first dorsal fin.
These sharks can reach a maximum length of 12 feet and weight up to 500 pounds.
They have very sharp, moderately large teeth, with blade smooth-edged with basal cusplets.
They are a dark blue-gray to brown dorsally and white underneath. It has a patch of white on the trailing edge of the first dorsal fin.
The Porbeagle sharks feed on squid, cod, hake, flounder, and other bottom dwelling fish.
Porbeagles are migratory and moves inshore and to surface in summer, winters offshore in deeper water to depths of 1,212 feet. Populations are segregated by age (size) and sex. They are inquisitive, may approach boats and divers.
They inhabit in cold waters of North Atlantic, South Atlantic, and South Pacific. They are found inshore to continental offshore fishing banks, occasionally open ocean.
The mackerel sharks are unique among sharks for their heat-exchanging circulatory system, which makes them, functionally, warm-blooded. They can capture the heat generated by their swimming muscles and, through a complicated arrangement of microscopic arteries and veins, use it to heat the blood. This blood is directed throughout their body, to the muscles, internal organs, and brain. As a result, their body temperature is higher than that of the surrounding water. This gives them an increased muscle strength and allows more rapid nervous-system activity. The Porbeagle has achieved the greatest body temperature elevation. It's body can be 20 F (11C) warmer than the frigid North Atlantic Ocean that it inhabits.
It reproduces viviparously, without a placental connection. As with other mackerel sharks, the older embryos feed on some of the eggs and smaller embryos in the uterus.
Porbeagles are strong, fast swimmers that are capable of rapid acceleration.
Common, although some statistics have been reported that some populations have been depleted due to commercial fisheries for high value of meat, and also a game fish.
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