Shortfin mako shark
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[Photo] Shortfin Mako Shark (Isurus oxyrinchus) in the Pacific ocean.
The shortfin mako shark, Isurus oxyrinchus, ("sharp nose") is a large shark of the Lamnidae family. Along with the closely related longfin mako, Isurus paucus, it is commonly called just mako shark.
Anatomy and appearance
With a full-grown length of 2.75 ??? 4 m (9 ??? 13 ft) it has been reported to weigh up to 800 kg (1,750 lb) and has a bluish back and white underside. Although the sexes grow at about the same rate, females are thought to have a longer life span, and grow larger and weigh more than the males. Shortfin makos are renowned for their speed and their ability to leap out of the water. In fact, there are cases that when an angry mako will jump out of the water and into the boat after it has been caught on the hook. Mako sharks have a better hydrodynamic shape than all other sharks, and this, combined with the lamnidae's typical high aerobic muscle mass, reflects in the spectacular speed and agility of both the longfin and shortfin makos.
The shortfin mako shark is a sleek spindle shaped shark with a long conical snout. This shark has short pectoral fins and a crescent shaped caudal (tail) fin. There is a distinct caudal keel on the caudal base. Its second dorsal fin is much smaller than the first. The teeth are slender and slightly curved with no lateral cusps, and are visible even when the mouth is closed. There is marked countershading on this shark: dorsally it is a metallic indigo blue while ventrally it is white.
Naming
The name "mako" comes from the M??ori language, but the etymology is unclear. A typical gloss given for "mako" is "large blue shark". The term entered the English language in 1727. It can also mean "man-eater".
Diet
The shortfin mako feeds mainly upon bony fishes including mackerels, tunas, bonitos and swordfish, but may also eat other sharks, porpoises and sea turtles.
Distribution
The shortfin mako is found in temperate and tropical seas worldwide. The closely related longfin mako shark, Isurus paucus, is found in the Gulf Stream or warmer offshore waters.
Shortfin mako sharks live in tropical and temperate offshore waters. They are a pelagic species that occur from the surface down to depths of 150 meters (490 feet). This shark is seldom found in waters colder than 16 degrees Celsius.
The shortfin mako is found worldwide. In the western Atlantic it can be found from Argentina and the Gulf of Mexico to Browns Bank off of Nova Scotia. In Canadian waters these sharks are not abundant as they prefer warm waters, but neither are they rare. Shortfin makos are often found in the same waters as swordfish as they are a source of food and both fish prefer similar environmental conditions.
Behavior
The shortfin mako's speed has been recorded at 50 km/h (31 mph) and there are reports that it can achieve bursts of up to 74 km/h (46 mph). Shortfin makos can jump up to 9 m (28 ft) in the air. Due to its speed and agility, this high-leaping fish is sought as game worldwide. This shark is highly migratory. They are also one of four warm-blooded sharks which helps them in their speed.
There is still some uncertainty about its life-span, but it is suspected to reach ages of between 11-23 years.
Reproduction
The shortfin mako shark is a yolk-sac ovoviviparous shark, meaning it gives birth to live young who feed from a sac full of yolk in the womb. The gestation period for a mako shark is 15 to 18 months. Shortfin mako embryos in the female's body consume each other to get nutrients. This is called intrauterine cannibalism.
Female shortfin makos usually become sexually mature at a length of 3 meters. Developing embryos feed on unfertilized eggs in the uterus during the gestation period of 15-18 months. The 4-18 surviving young are born live in the late winter and early spring at a length of about 70 cm, but have no placental connection during development (ovoviviparity). It is believed that females may rest for 18 months after birth before the next batch of eggs are fertilized.
Trivia
Distinguishing Characteristics
??? Teeth are visible even when the mouth is closed
??? Teeth are long and slender with smooth-edged cusps
??? Distinct countershading, dorsally blue and ventrally white
??? Moderately short pectoral fins
??? Underside of the snout is white
??? Lunate tail and caudal keel
http://en.wikipedia.org/wiki/Shortfin_mako_shark
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