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Archive for May 2010

Above the Cow shark

1. There are just four species of cow shark and they are Sharpnose seven-gill shark, Bluntnose sixgill shark, Bigeye sixgill shark and Broadnose sevengill shark

2. The Cow shark grow up to 1.4 meters (4.6 ft) to over 5.5 meters (18 ft) in length.

3. Unlike most shark the cow shark and it’s family have 7 or 6 gill slits on both side.

4. The Cow shark skeleton resemble that of the ancient extinct shark with few modern adaptations.

5. The Cow sharks are ovoviviparous with the mother retaining the egg-cases in her body until they hatch.

6. They feed on relatively large fish of all kinds, including other sharks, as well as on crustaceans and carrion.

All of this info is from http://en.wikipedia.org/wiki/Cow_shark

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Above the Blacktip shark

1. The black tip shark is found worldwide in the tropical and subtropical waters. In the Atlantic and Indian Ocean, the western Pacific ocean. Most blacktip sharks are found in water less than 30 m (100 ft) deep. It may dive to 64 m (210 ft). The Favored habitats are muddy bays, island lagoons, and the drop-offs near coral reefs. Although an individual may be found some distance offshore, blacktip sharks are not found in oceans waters.

2. The blacktip shark has a robust, streamlined body with a long, pointed snout and relatively small eyes. They have five gill slits but are longer than a normal size shark. The jaw has 15 rows or both sides. They are gray to brown above and white below. With a white stripe running along the sides. They have a blacktip only on one fin. The maximum known length of 2.8 m (9.0 ft), though 1.5 m (4.9 ft) is more typical, and a maximum known weight of 123 kg (271 lb).

3. Juveniles. In Terra Ceia Bay, Florida, a nursery area for this species, juvenile blacktips form aggregations during the day and disperse at night. They aggregate most strongly in the early summer when the sharks are youngest, suggesting that they are seeking refuge from predators.

4. Like the spinner shark, the blacktip shark is known to leap out of the water and spin three to four times about its axis before landing.

5. Fish make up some 90% of the blacktip shark’s diet. A wide variety of fishes have been recorded as prey for this species: sardines, herring, anchovies, ladyfish, sea catfish, cornetfish, flatfish, threadfins, mullet, mackerel, jacks, groupers, snook, porgies, mojarras, emperors, grunts, butterfish, tilapia, triggerfish, boxfish and porcupinefish. They also feed on rays and skates, as well as smaller sharks such as smoothhounds and sharpnose sharks. Crustaceans and cephalopods are occasionally taken. They hunt at dawn and dusk. They also have been known to have a feeding frenzies when large quantities of food are suddenly available.

6. Likes most shark the blacktip is a  viviparity and gives birth to 4-7 pups every other year. Making use of shallow coastal nurseries that offer plentiful food and fewer predators.
Mating occurs from spring to early summer, and the young are born at around the same time the following year after a gestation period of 10–12 months.  The age at maturation is 4–5 years for males and 7–8 years for females. The lifespan is at least 12 years.

7. There are reports of blacktip sharks showing curiosity towards divers, but remaining at a safe distance. it is not regarded as highly dangerous to humans. However, they may become aggressive in the presence of food, and their size and speed invite respect. As of 2008 there have been 28 unprovoked attacks and one fatal and 13 provoked attacks by this species.

All of this info is from http://en.wikipedia.org/wiki/Blacktip_shark

Above the Thresher shark

1. There are three types thresher shark they are Pelagic thresher, Bigeye thresher, Common thresher.

2. Although occasionally sighted in shallow, inshore waters, thresher sharks they prefer the open ocean and will not go no deeper than 500 meters (1,600 ft). Common threshers tend to be more common in coastal waters over continental shelves. In the North Pacific, common thresher sharks are found along the continental shelves of North America and Asia. They are rare in the Central and Western Pacific. In the warmer waters of the Central & Western Pacific, bigeye and pelagic thresher sharks are more common.

3. The Common thresher which may reach a length of 6.1 meters (20 ft) and a weight of over 500 kilograms (1,100 lb). The Bigeye thresher can grow to a length of 4.9 m (16 ft). And the Pelagic thresher is the smallest at 3 m (10 ft) long.

4. The thresher shark eats fish(such as bluefish, juvenile tuna and mackerel, squid and cuttlefish are the primary food items of the thresher sharks. They are known to follow large schools of fish into shallow waters. Crustaceans and the odd seabird are also taken.

5. Thresher sharks are solitary creatures which keep to themselves. In the Indian ocean they are separated by depth and space according to gender. When hunting fish the thresher sharks are known to “slap” the water, herding and stunning prey. Thresher sharks are one of the few shark species known to jump fully out of the water making turns like dolphins, this behaviour is called breaching.

6. Fertilization and embryonic development occur internally this ovoviviparous or live-bearing mode of reproduction results in a small litter (usually 2 to 4) of large well-developed pups, up to 150 cm at birth in thintail threshers. The young fish exhaust their yolk sacs while still inside the mother, at which time they begin feeding on the mother’s unfertilized eggs this is known as oophagy. Thresher sharks are slow to mature, males reaching sexual maturity between 7 and 13 years of age and females between 8 and 14 years in bigeye threshers. They may live for 20 years or more.

All of this info is from http://en.wikipedia.org/wiki/Thresher_shark

Above the Spinner shark

1. People mistake the black tip shark for the spinner shark. They live in the western Atlantic ocean and the eastern Atlantic. And pass throw the Indian Ocean. They can be found at a depth of 100 m (330 ft) or at the surface at less than 30 m (100 ft) deep. It prefers shallow water. In the spring and the summer they are found in warm inshore water. and in the winter they move south into deeper water.

2. The average spinner shark is 2 m (6.4 ft) long and weighs 56 kg (123 lbs). The maximum known length and weight of 3 m (10 ft) and 90 kg (198 lbs). Indo-Pacific sharks are generally larger than those from the northwest Atlantic. This species has a slim body. The eyes are small and circular. The tooth rows number 15–18 in each half of the upper jaw and 14–17 in each half of the lower jaw. The teeth have long and narrow central cusps and are finely serrated in the upper jaw and smooth in the lower jaw. The five pairs of gill slits are long. The first dorsal fin is relatively small.  There is no ridge between the first and second dorsal fins. The pectoral fins are moderately short, narrow, and falcate (sickle-shaped). Young individuals have no black tip on its fin.
And on one of the fin it has a black band on both sides of the fin. But not all over the fin.

3. The spinner shark is a fast swimmer that sometimes forms large schools. Young individuals prefer cooler water temperatures than adults. Off South Africa, females are found close to shore year-round while males only appear during the summer. Smaller spinner sharks may be preyed upon by larger sharks.

4. Spinner sharks feed on small bony fishes including tenpounders, sardines, herring, anchovies, sea catfish, lizardfish, mullets, bluefish, tunas, bonito, croakers, jacks, mojarras, and tongue-soles. They have also been known to eat stingrays, cuttlefish, squid, and octopus.

5. The spinner shark is viviparous. Adult females have a single functional ovary and two functional uteruses each uterus is divided into compartments one for each embryo. The embryos are initially sustained by a yolk sac. When the embryo grows to around 19 cm (7.5 in) long the supply of yolk has been exhausted and the empty yolk sac develops into a placental connection through which the mother provides nutrients for the remainder of gestation. This species has the smallest ova relative to the fully developed embryo of any viviparous shark known. Females give birth to 3–20 (usually 7–11) pups every other year after a gestation period of 11–15 months. Mating occurs from early spring to summer and parturition in August off North Africa from April to May off South Africa, and from March to April in the northwestern Atlantic. Young are birthed in coastal nursery areas such as bays, beaches and high-salinity estuaries in water deeper than 5 m (20 ft).The length at birth is 66–77 cm (26–30 in) in the northwestern Atlantic, 61–69 cm (24–27 in) off Tunisia and 60 cm (24 in) off South Africa. Males mature at 1.8 m (5.9 ft) and females at 2.1 m (6.9 ft). Spinner sharks generally do not reproduce until they are 12–14 years old. The maximum lifespan has been estimated at 15–20 years or more.

6. As of 2008 there has been 16 unprovoked attacks and 1 provoked attack attributable to the spinner shark and none of them fatal.

All of this info is from http://en.wikipedia.org/wiki/Spinner_shark