Sharksonline's Blog

Above the Blue shark

1. The blue shark is found worldwide in deep temperate and tropical waters from the surface to about 350 meters. In temperate sea it may come closer to shore where it can be seen by divers but while in tropical waters it occurs at greater depths. It is found from as far north as Norway to as far south as Chile. Blue sharks are found off the coasts of every continent but except for Antarctica. It prefers waters with a temperature range of 7 to 16°C but will tolerate temperatures of 21°C or above.

2. Blue sharks are light-bodied with long pectoral fins. The top of the body is deep blue and lighter on the sides and the underside is white. A blue shark grows to 3.8 m (12.5 ft) long. The shark’s typical weight is 136 kg (300 lb) to 182 kg (400 lb) and can grow to 205 kg (450 lb). The highest reported weight was 391 kg (861 lb). They are rarely mistake with other sharks.

3. The blue sharks has a diet of squid, cuttlefish and pelagic octopuses, as well as lobster, shrimp, crab and a large number of bony fishes, small sharks, mammalian carrion and occasional sea birds. Whale and porpoise blubber and meat have been retrieved from the stomachs of captured specimens and they are known to take cod from trawl nets. Apparently blue sharks do not or only very rarely, eat tuna.

4. The female blue shark have 4 to 135 pups per litter. The gestation period is between 9 and 12 months. Females mature at 5 to 6 years of age and males at 4 to 5. It is believed mating involve biting by the male. Female blue sharks have skin 3 times as thick as that of males so the biting does not leave them bleeding.

5. Blue sharks are the most heavily fished sharks in the world mainly as result of by-catch. It is estimated that 10 to 20 million individuals are killed each year as a result of fishing. The sharks skin is used for leather, the fins for shark-fin soup and the liver for oil. Blue sharks are occasionally catch for game fish and they are frequent accidental catches by commercial fisherman seeking swordfish or tuna. Blue sharks are not considered dangerous and rarely have been known to attack humans. Most attacks between blue sharks and humans take place in deep water and on small boats as they rarely come close to shore. As of 2008, there has only been 3 encounters with humans and one fatal.

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

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Above the Scalloped hammerhead  shark

There are nine known species of the hammerhead shark and here they are

Scalloped hammerhead

Great hammerhead

Smooth hammerhead

Whitefin hammerhead

Scalloped bonnethead

Winghead shark

Scoophead

Bonnethead or shovelhead

Smalleye hammerhead

1. And they range from 0.9 to 6 m (3.0 to 20 ft) long. All the species have a head that gives it a resemblance to a flattened hammer. The hammer-like shape of the head was thought to help sharks find food. However the positioning of the eyes allow for it to see 360 degree that is the best known vision of any shark. Like all sharks, hammerheads have electroreceptory sensory pores to help it find food. Because of it hammer like head hammerheads can sweep for prey more effectively. These sharks have been able to detect an electrical signal of half a billionth of a volt. They are also known to form schools during the day sometimes in groups of over 100. In the evening like other sharks, they become solitary hunters.

2. The hammerhead shark females giving birth to live young. Like other sharks, the male transferring sperm to the female through one of two claspers. In 2007, the bonnethead shark was found to be capable of asexual reproduction by herself without the need for a male. This was the first shark known to do this.

4. Hammerhead sharks are known to eat a large range of things, including fish, other sharks, squid, octopus, and crustaceans. Stingrays are a favourite. They are also known to eat their own young.

5. One of the nine known species of hammerhead, three can be dangerous to humans and they are the scalloped, great and smooth hammerheads. The great and the scalloped hammerhead are listed on the World Conservation Union’s (IUCN) 2008 Red List as endangered.

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

Above the Grey nurse or most known as the sand tiger shark

And down is the Nurse shark

1. In Australia the sand tiger is known as the Grey nurse shark and in Africa it is known as the spotted ragged tooth shark. Not to be confused with nurse shark there are to different sharks they look different too

2. Despite a fearsome appearance and strong swimming abilities. It is a slow-moving animal, it is not considered aggressive unless provoked.

3. It grows to a length of 3.2 m (about 10.5 ft). Male Grey nurse sharks mature at 2.1 m (about 6′ 11″) and females mature at 2.2 m (about 7′ 3″). This shark weighs 90 to 160 kg (200 to 350 lb).

4. The diet of this shark including bony fish and mackerels and other sharks, rays,squid,crabs and lobsters.

5. The sharks lives at depths of between 60 and 190 m, although deeper depths have been recorded. Often they will shelter in caves or gutters during the day and come out at night to feed. During the day they slow and sluggish behavior, becoming more active during the night. While it is commonly reported that grey nurse sharks are harmless. Data compiled by ISAF records 76 attacks on humans of which 29 have been classified as unprovoked. Two of those unprovoked attacks have resulted in fatal.

6. This shark bears live young from eggs which hatch inside the uterus. Female sharks have two uterus’s. Inside the uterus the young sharks develop and eat each other until there are only two young left, one in each of the uteri. To feed her two pups she continues to produce eggs that are eaten by her two remaining young. After two years the young are around 1 m long and look like their mother and fully able to fend for themselves and she gives birth to them. This  reproductive strategy is making it harder for the shark population to rebound from near extinction.

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

Above the Grey reef shark

1. The Grey reef shark is native to the Indian and Pacific Oceans. In the Indian Ocean it occurs from South Africa to India including Madagascar and nearby islands, the Red Sea and the Maldives. In the Pacific Ocean it is found from southern China to northern Australia and New Zealand including the Gulf of Thailand the Philippines and Indonesia. Generally a coastal shallow-water species Grey reef sharks are mostly found in depths of less than 60 m (200 ft). However they have been known to dive to 1,000 m (3,300 ft). They are frequently found near the drop-offs at the outer edges of the reef and less commonly within lagoons. On occasion this shark may travel a few kilometers out into the open ocean.

2. The Grey reef shark has 13–14 tooth rows on each side of both jaws. The teeth are larger in the upper jaw than in the lower jaw. The first dorsal fin is medium-sized and a bit more down is the second dorsal fin. The color of this shark is grey sometimes with a bronze and white below. Grey reef sharks that spend time in shallow water eventually darken in color, due to tanning. Most Grey reef sharks are less than 1.9 m (6.2 ft) long. The maximum reported length is 2.6 m (8.4 ft) and the maximum reported weight is 33.7 kg (74.3 lb).

3. Grey reef sharks feed mainly on bony fishes, squid and octopus, crabs, lobsters. Grey reef sharks hunt individually or in groups. They have been known to pin schools of fish against the outer walls of coral reefs for feeding. Their sense of smell is extremely acute being capable of detecting one part tuna in 10 billion parts of sea water. This shark has been known to go in to a  feeding frenzy. In one documented frenzy caused by an underwater explosion that killed several snappers and one of the sharks involved was attacked and consumed by the others.

5. Grey reef sharks are active all times of the day and night. A group of around 30 sharks spend the day together in a small part of their home range, dispersing at night into shallower water to forage for food. The home range of a Grey reef shark is about 0.8 km2 (0.31 sq mi). There is little evidence of territoriality in the Grey reef shark individuals will tolerate others of their species entering and feeding within their home ranges. Off Hawaii, individual Grey reef sharks may stay around the same part of the reef for up to three years, while at Rangiroa they regularly shift their location by up to 15 km (9.3 mi). Individual Grey reef sharks at Enewetak become highly aggressive at specific locations suggesting that they may dominant behavior over other sharks in their home areas.

6. Social aggregation is well-documented in Grey reef sharks. large numbers of pregnant adult females have been seen slowly swimming in circles in shallow water occasionally exposing their dorsal fins or backs. These groups last from 11:00 A.M. to 3:00 P.M. A female Grey reef sharks form aggregations in shallow water from March to June. The number of sharks per group differs from year to year. Each day the sharks begin arriving at the aggregation area at 9:00 A.M. reaching a peak in numbers during the hottest part of the day in the afternoon and dispersing by 7:00 P.M. Individual sharks return to the aggregation site every one to six days. Grey reef sharks different social behaviors on different parts of the reef. Sharks tend to be solitary on shallower reefs. Near reef drop-offs, loose aggregations of 5–20 sharks form in the morning and grow in number throughout the day before dispersing at night. In some areas, sharks form schools of around 30 individuals near the sea bottom, arranging themselves parallel to each other or slowly swimming in circles. Most individuals within schools are females. And pups may form schools to keep safe.

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

Above the shortfin mako shark
And down a longfin mako shark

There are to species of Mako sharks the shortfin mako and the longfin mako. So i will start with the shortfin mako shark

1. The shortfin mako grows to a length of 1.82–3.2 m (6–10 ft) and weights 60–400 kg (135-880 lb). The largest confirmed size was 3.96 m (13 ft) and 794 kg (1,750 lb). It has a bluish back and white underside.  Shortfin makos are known for their speed and their ability to leap out of the water. The shortfin mako shark is a sleek spindle-shaped shark with a long snout. This shark has short fins. It’s second dorsal fin is much smaller than the first. The apex of pectoral fin and first dorsal fin are rounded in younger makos. The teeth are slender and slightly curved.

2. The shortfin mako feeds mainly upon bony fishes, mackerels, tunas, bonitos, swordfish and sailfish, sometimes eat other sharks, porpoises, sea turtles, and seabirds. Makos swims deeper than the their prey so they have a good view of what is above and have a chance of seeing and attacking their prey before they are seen themselves.

3. The shortfin mako is most of the time found in warmer offshore waters and tropical seas worldwide. It species that can be found from the surface down to depths of 150 m (490 ft.). The shortfin mako is found in blue waters normally far from land. And sometimes closer to shore around islands.

4.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). It can jump up to 9 m (28 ft.) in the air. They do not know how long its lifespan is they think it lives to 12 to 24 years.

5. The shortfin mako shark gives birth to live young. Developing embryos feed on unfertilized eggs produced by the mother in the uterus. And gestation period is 15 to 18 months. The 4 to 18 surviving young are born live in the late winter and early spring at a length of about 70 cm. While a male shortfin mako need 4 1/2 to 5 years to reach 136 kg (2 m) and female reaches 227 kg (2.7 to 2.9 m) in 7 years when matured. It is believed shortfin makos travel long distances to seek food or to mate. One mako is known to swim 1,322 miles (2,128 km) in 37 days averages 36 miles (58 km) a day.

6. Between 1580 and 2007 the shortfin mako has had eight recorded unprovoked attacks on humans with two being fatal and twenty boat attacks.

And now some facts about the longfin mako shark

1. They believe that the longfin mako lives worldwide in tropical and warm-temperate oceans. They do not know because they get mistake for the shortfin mako. but they know it is found in the Atlantic Ocean and the Gulf Stream off the east coast of the United States, Cuba and southern Brazil in the west, and from the Iberian Peninsula to Ghana in the east possibly including the Mediterranean Sea and Cape Verde. In the Indian Ocean it has been reported from the Mozambique Channel. In the Pacific Ocean it occurs off Japan and Taiwan northeastern Australia a number of islands in the Central Pacific northeast of Micronesia and southern California.

2. The longfin mako is the larger of the two makos and the second-largest species in its family, growing to 2.5 m (8.2 ft) long and weighing over 70 kg (150 lb). Females are larger than males. The largest reported longfin mako was a 4.3 m (14 ft) long female caught with a long pointed snout and large eyes. There are 12–13 tooth rows on either side of the upper jaw and 11–13 tooth rows on either side of the lower jaw. The gill slits are long. The pectoral fins are as long or longer than the head with a nearly straight front margin and broadly tips. The first dorsal fin is large with a rounded apex and is placed behind the pectoral fins. The second dorsal and anal fins are tiny. The caudal peduncle is expanded laterally into strong keels. The caudal fin is crescent-shaped with a small notch near the tip of the upper lobe. The coloration is dark blue to grayish black above and white below. The unpaired fins are dark except for a white rear margin on the anal fin the pectoral and pelvic fins are dark above and white below with sharp gray posterior margins.  Off Cuba it is most frequently caught at a depth of 110–220 m (360–720 ft) and is rare at depths above 90 m (300 ft). Off New South Wales, Australia most catches occur at a depth of 50–190 m (160–620 ft) in areas with a surface temperature around 20–24 °C (68–75 °F).

4. The longfin mako is less active than the shortfin mako shark. For it’s diet it mainly has small bony fishes and squids. Adult longfin makos likely have no natural predators while young mako sharks may fall prey to larger sharks. The longfin mako gives birth to two pups at a time one inside each uterus. The pups measure 97–120 cm (3.2–3.9 ft) long at birth. It is suggested that during the winter females swim into shallow coastal waters to give birth. Male and female sharks reach sexual maturity at lengths of about 2 m (6.6 ft) and 2.5 m (8.2 ft).

5. They have been no attacks on humans from the longfin mako shark. But nevertheless it big size and it’s teeth make it a little bit dangerous.

All of this info is from http://en.wikipedia.org/wiki/Longfin_mako_shark And http://en.wikipedia.org/wiki/Shortfin_mako_shark

Above the oceanic whitetip shark

1. The oceanic whitetip is found globally in deep open water with a temperature greater than 18 °C (64 °F). It prefers waters between 20 °C (68 °F) and 28 °C (82 °F) and tends to withdraw from areas when temperatures fall below this. They are found worldwide between 45° north and 43° south latitude.The shark spends most of its time in the upper layer of the ocean—to a depth of 150 meters (490 ft) and prefers off-shore deep-ocean areas. Sometimes it is found close to land in waters as shallow as 37 meters (120 ft) mainly around mid-ocean islands such as Hawaii or in areas where the continental shelf is narrow and there is access to nearby deep water. It is active both day and night.

2. The Oceanic whitetip most distinguishing characteristics are its long wing-like pectoral and dorsal fins. The fins are significantly larger than most other shark species. The shark’s nose is rounded and its eyes are circular with nictitating membranes. It is bronze brown bluish or Grey dorsally and white ventrally. Its maximum size is 4 meters (13 ft), although usually it does not exceed 3 meters (10 ft). Its maximum reported weight is 170 kilograms (370 lb). The female is typically larger than the male by 10 centimeters with males about 1.8 meters and females about 1.9 meters. Most of its fins (dorsal, pectoral, pelvic, and caudal) have white tips (juvenile specimens and some adults may lack these). A saddle-like marking may be apparent between first and second dorsal fins. The shark has several kinds of teeth—those in the mandible (lower jaw) have a thin serrated tip and are relatively small and triangular. There are between 13 and 15 teeth on either side. The teeth in the upper jaw are triangular but much larger and broader with entirely serrated edges—there are 14 or 15 along each side.

3. Oceanic whitetip mainly on pelagic cephalopods and bony fish. However its diet can be far more varied and less selective—it is known to eat threadfins, stingrays, sea turtles, birds, gastropods, crustaceans, mammalian carrion, and even rubbish dumped from ships. The bony fish it feeds on include lancetfish, oarfish, barracuda, jacks, dolphinfish, marlin, tuna, and mackerel. Its feeding methods include biting into groups of fish and swimming through schools of tuna with an open mouth. When feeding with other species it becomes aggressive.

4. The oceanic whitetip is usually solitary and slow-moving and tends to cruise near the top of the water searching for food. The oeanoc whitetip have been known to follow ships (dog-like behavior) and ready to rush in if the opportunity presents itself. Oceanic whitetips are not fast swimmers but they are capable of surprising bursts of speed. Groups often form when individuals see a large food source and go in to a “feeding frenzy” they will bit everything and eat it.

5. Mating season is in early summer in the northwest Atlantic Ocean and southwest Indian Ocean although females captured in the Pacific have been found with embryos year-round suggesting a longer mating season. Its gestation period is one year. Litter sizes vary from one to 15 with the young born at a length of about 0.6 meters. Sexual maturity is reached at close to 1.75 meters  for males and 2 meters for females.

6. The oceanic whitetip is responsible for more fatal attacks on humans than all other species combined as a result of predation on survivors of shipwrecks or downed aircraft. USS Indianapolis on 30 July 1945 accounting for 60 to 80 sailors. Tiger sharks may have been responsible for some deaths. Also during World War II the Nova Scotia a steamship carrying approximately 1,000 people near South Africa was sunk by a German submarine. With only 192 survivors many deaths were attributed to the whitetip.

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

Above the tiger shark

1. Mature sharks average 3.25 to 4.25 meters (10.7 to 13.9 ft) long and weigh 385 to 635 kilograms (850 to 1,400 lb). It can attain a length of over 5 meters (16 ft) and a weight of 1,110 kilograms (2,400 lb) at maximum

2. It is found in many tropical and temperate oceans and is especially common around central Pacific islands

3. This shark is a solitary and mostly night-time hunter

4. The tiger shark is a predator known for eating a wide range of animals. It’s usual diet consists of fish, seals, birds, smaller sharks, squid, turtles, and dolphins. Tigers have been found with man-made waste such as license plates or pieces of old tires in their digestive tracts. this shark is well-known as “the wastebasket of the sea”.

5. This shark second only to the great white shark in number of recorded attacks on humans the tiger is considered to be one of the sharks most dangerous to humans along with the great white shark, bull shark and the oceanic whitetip shark

6. The tiger shark is often found close to the coast, in mainly tropical and sub-tropical waters worldwide, though they can reside in temperate waters. Tiger sharks are among the largest predatory sharks after the great white. The shark’s behavior is primarily nomadic but is guided by warmer currents and it stays closer to the equator throughout the colder months. The shark tends to stay in deep waters that line reefs but does move into channels to pursue prey in shallower waters. This shark has been recorded down to a depth of 900 meters (3,000 ft) but is also known to move into shallow water that is normally too shallow for a species of its size.

7. Its skin can typically range from blue to light green with a white or light yellow underbelly. Dark spots and stripes are most visible in young sharks and fade as the shark matures. It has been estimated that the tiger shark can swim at a maximum speed of around 32 kilometers per hour (20 mph) with short bursts of higher speeds.

8. Females mate once every 3 years. Mating in the northern hemisphere takes place between March and May with birth between April and June the following year. In the southern hemisphere mating takes place in November or December or early January. The tiger is an ovoviviparous which mean its eggs hatch internally and the young are born live when fully developed. The young develop inside the mother’s body for up to 16 months. Litters range from 10 to 80 pups. A newborn is generally 51 centimeters to 76 centimeters long. It is unknown how long tiger sharks live but they can live longer than 12 years.

9. Tough shark attacks are rare the tiger is responsible for a large percentage of fatal attacks and is regarded as one of the most dangerous species. Tiger sharks are often found in river estuaries and harbours as well as shallow water close to shore, where they are bound to encounter humans. Tiger sharks also dwell in river mouths and other runoff-rich water.

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