Thursday, January 24, 2008

Zebra Shark


The zebra shark, Stegostoma fasciatum, is a common carpet shark of inshore Indo-Pacific waters notable for its very long caudal fin, nearly as long as its body. It is the only species in the family Stegostomatidae and the genus Stegostoma.
The zebra shark is a slow-moving type, often just sitting on the seafloor in the vicinity of coral reefs, on sandy or rocky bottoms. Unlike most types of sharks, it does not need to move, and instead pumps water through its gills. This is known as the ram-jet effect.
It is a very sleek and slender shark, about 3.5m (11.5 ft) long. In addition to the long tail, the zebra shark has distinctive ridges running down its body. As its names suggest, it is patterned; young sharks are dark with yellowish stripes, changing to an adult pattern of a tan color with dark spots, found all over including the fins. The snout is rather rounded, with small barbels (whiskers).
Zebra sharks do well in captivity, and a number of aquariums around the world have them on display. They are fished commercially on a small scale. They are often seen by scuba divers, and will lay still on the bottom as long as a diver does not come too close. They are harmless to divers as long as they are not disturbed. In addition several aquariums have shown them to be easy learners, even teaching them to respond to touch by flapping their gills. Due to its large caudal fins, this species are a prized catch for fishermen to make shark fin soup

Wobbegong Shark


Wobbegong is the common name given to the eight species of carpet sharks in the family Orectolobidae. They are found in shallow temperate and tropical waters of the western Pacific Ocean and eastern Indian Ocean, chiefly around Australia and Indonesia, although one species (the Japanese wobbegong, Orectolobus japonicus) occurs as far north as Japan.

Wobbegongs are bottom-dwelling sharks which spend much of their time resting on the sea floor, often among rocks or under ledges. The largest species, the spotted wobbegong, Orectolobus maculatus, grows up to 3.2 m long. Wobbegongs are well camouflaged with a symmetrical pattern of bold markings which resembles carpet. Because of this striking pattern, wobbegongs and their close relatives are often referred to as carpet sharks. The camouflage is improved by the presence of small vegetation-like flaps of skin around the wobbegong's mouth. Wobbegongs make use of their relative invisibility to hide among rocks and ambush smaller fish which swim too close (animals which feed in this way are called ambush predators).

Wobbegongs are generally not dangerous unless they are provoked. They have bitten people who accidentally step on them in shallow water; they may also bite scuba divers or snorkellers who poke or handle them, or who block their escape route. Wobbegongs are very flexible and can easily bite a hand that is holding on to their tail. They have many small but sharp teeth and their bite can be severe, even through a wetsuit; having once bitten, they have been known to hang on and can be very difficult to remove.To avoid being bitten, divers should avoid accidental contact.
Although wobbegongs do not eat humans, humans frequently eat wobbegongs; the flesh of a wobbegong or other shark is called flake and it is often used in fish and chips in Australia. Wobbegong skin is also used to make leather.
The word wobbegong is believed to come from an Australian Aboriginal language.

White Tip Shark



The oceanic whitetip shark, Carcharhinus longimanus, is a large pelagic shark of tropical and warm temperate seas. It is a stocky shark, most notable for its long, white-tipped, rounded fins.

This aggressive but slow-moving fish dominates feeding frenzies, and is a suspected danger to survivors of oceanic shipwrecks and downed aircraft. Recent studies. have shown that its numbers are in steep decline as its large fins are highly valued as the chief ingredient of shark fin soup and, as with other shark species, the oceanic whitetip faces mounting pressure from fishing throughout its range.

Whale Shark


The whale shark, Rhincodon typus, is a slow filter feeding shark that is the largest living fish species. This distinctively-marked shark is the only member of its genus Rhincodon and its family, Rhincodontidae (called Rhinodontes before 1984), which is grouped into the subclass Elasmobranchii in the class Chondrichthyes. The shark is found in tropical and warm oceans and lives in the open sea. The species is believed to have originated about 60 million years ago
This species, despite its enormous size, does not pose any significant danger to humans. It is a frequently cited example when educating the public about the popular misconceptions of all sharks as "man-eaters". They are actually quite gentle and can be playful with divers. There are unconfirmed reports of sharks lying still, upside down on the surface to allow divers to scrape parasites and other organisms from their bellies. Divers and snorkellers can swim with this giant fish without any risk apart from unintentionally being hit by the shark's large tail fin.
The shark is often seen by divers in The Bay Islands in Honduras, Thailand, the Philippines, the Maldives, the Red Sea, Western Australia (Ningaloo Reef), Gladden Spit Marine Reserve in Belize, Tofo Beach in Mozambique, Sodwana Bay (Greater St. Lucia Wetland Park) in South Africa and at the Galapagos Islands.
The highest concentration of whale sharks to be found anywhere in the world is in the Philippines. From January to May, they congregate in the shallow coastal waters of Sorsogon province (at Donsol). Lucky divers have also come across whale sharks in the Seychelles and in Puerto Rico. Between December and September, they are well known to swim along the bay of La Paz in Mexico's Baja California. Sometimes, they are accompanied by smaller fish, in particular, the remora. Recently, they have been seen in the vicinity of Tenggol Island, off the east coast of West Malaysia.[citation needed]They are also frequently spotted around other Coral Reefs along the West Malaysian coast including Kapas Island and Redang Island.

Tiger Shark


The tiger shark, Galeocerdo cuvier, one of the largest sharks, is the only member of the genus Galeocerdo. Mature sharks average 3.25 metres (11 ft) to 4.25 metres (14 ft)[3] [4] and weigh 385 to 909 kg (850 to 2000 lb).[5] It is found in many of the tropical and temperate regions of the world's oceans, and is especially common around islands in the central Pacific. This shark is a solitary hunter, usually hunting at night. Its name is derived from the dark stripes down its body, which fade as the shark matures.
The tiger shark is a dangerous predator, known for eating a wide range of items. Its usual diet consists of fish, seals, birds, smaller sharks, squid, and turtles. It has sometimes been found with man-made waste such as license plates or pieces of old tires in its digestive tract. It is notorious for attacks on swimmers, divers and surfers in Hawaii; and is often referred to as the "bane of Hawaiian surfers"[6] and "the wastebasket of the sea".
The tiger shark is second only to the bull shark in number of recorded human fatalities [3] and is considered, along with the great white, bull shark, and the oceanic whitetip shark to be one of the sharks most dangerous to humans. [7] Tiger Sharks are most commonly found in Peru on the coast of Punta Sal. Tiger sharks migrate yearly to the warmer waters of Punta Sal, Peru during the months of January thru to March for feeding and mating.
Although shark attacks on humans are a relatively rare phenomenon, the tiger shark is responsible for a large percentage of the fatal attacks that do occur on humans, and is regarded as one of the most dangerous species of sharks. Tiger sharks reside in temperate and tropical waters. They are often found in river estuaries and harbours, as well as shallow water close to shore, where they are bound to come into contact with humans. Because of their curious nature of feeding it is expected that a tiger shark would normally attack a human if it came in contact with it. Tiger sharks are known to dwell in waters with runoff, such as where a river enters the ocean.
Tiger sharks have become a recurring problem in Hawaii and are considered the most dangerous shark species in Hawaiian waters. They are considered to be sacred 'aumakua' or ancestor spirits by the native Hawaiians, however between 1959 and 1976, 4,668 tiger sharks were hunted down in an effort to control what was proving to be detrimental to the tourism industry. Despite these numbers, little decrease was ever detected in the attacks on humans. It is illegal to feed sharks in Hawaii and any interaction with them such as cage diving is discouraged.[11]
While the tiger shark is not directly commercially fished, it is caught for its fins, flesh, liver, which is a valuable source of vitamin A used in the production of vitamin oils, and distinct skin, as well as by big game fishers.[3]
Tiger shark's fins are known as sea tiger fins (traditional Chinese:海虎翅) in Chinese cuisine. It is used for making shark fin soup and is very popular among the affluent in China.

Thresher Shark


Thresher sharks are large lamniform sharks of the family Alopiidae. Found in all temperate and tropical oceans of the world, the family contains three species all within the genus Alopias
Although occasionally sighted in shallow, inshore waters, thresher sharks are primarily pelagic; they prefer the open ocean, staying within the first 500 m of the water column. 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.
Thresher sharks are solitary creatures which keep to themselves. It is known that thresher populations of the Indian Ocean are separated by depth and space according to gender. All species are noted for their highly migratory or oceanodromous habits.

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.
Like all large sharks, threshers are slow growing and are therefore threatened by commercial fisheries. Other than for its meat, the sharks are hunted for their liver oil, skin (for leather), and their fins, for use in shark-fin soup.
They do not appear to be a threat to humans, although some divers have been hit with the upper tail lobe. There is an unconfirmed account of a fisherman being decapitated by a tail swipe as the shark breached.
Thresher sharks are classified as prized gamefish in the United States and South Africa. Common thresher sharks are the target of a popular recreational fishery off Baja Mexico. Thresher sharks are managed in some areas for their value as both a recreational sport fish and commercial species.

Taiwan Gulper Shark


Taiwan Gulper Shark :
Size: 1.5m
Weight: Unknown
Food Sources: Small fish
Habitat: depths around 250 meters
Locations: Taiwan
Interesting Facts: None

Spiny Dogfish Shark


The spiny dogfish shark is the most abundant shark. This small shark is also known as the piked dogfish, skittledog, spotted dogfish, white-spotted dogfish, codshark, and thorndog. Its dorsal fin has spines that are mildly poisonous. More is known about it than any other species of shark; it is often studied in scientific laboratories. It is used extensively by people as food, fertilizer, hide, pet food, and liver oil.
The spiny dogfish shark is a small shark that is deep gray with some white spots; the belly is off-white. It had two dorsal fins, each preceded by a mildly poisonous spin. It has a short snout, large eyes and no anal fin.
TEETH
The smooth teeth are located in rows which rotate into use as needed. The first two rows are used in obtaining prey, the other rows rotate into place as they are needed. As teeth are lost, broken, or worn down, they are replaced by new teeth that rotate into place.
SIZE
Spiny dogfish sharks average 3-4 feet (0.9-1.2 m) long.
DIET AND FEEDING HABITS
It eats mostly fish (including other sharks), but also eats squid and octopus.
SPINY DOGFISH SHARK ATTACKS
Dogfish are not considered to be dangerous, but some damage could be done by their teeth and their slightly poisonous dorsal fin spines.
SOCIAL GROUPS
Spiny dogfish sharks are gregarious (social) and travel in schools of hundreds to thousands of individuals. These schools are sometimes segregated by sex and age. They are called dogfish because they travel and hunt in packs. They also migrate in schools, following cool waters.
HABITAT
The spiny dogfish shark stays in water that is between 45°F - 59°F (7°C - 15°C). It will venture into brackish waters. Dogfish are mostly bottom-dwellers, dwelling in depths from the surface down to 400 fathoms (2,400 feet).
DISTRIBUTION
The spiny dogfish shark is found worldwide in temperate and subarctic waters, in the temperate and subarctic latitudes of the North Atlantic and North Pacific oceans. These sharks have even been found in the Black sea and Mediterranean sea.

Smooth Dogfish Shark


The smooth dogfish has a slender body with an obvious spiracle behind the eye. The caudal fin has a rounded lower lobe and a larger top lobe. The teeth are very small, blunt, numerous and similar in both the upper and lower jaw. This shark is olive gray or brown on top and yellow or grayish white below. The smooth dogfish is able to change its colour slowly through contraction of melanophores (migratory pigment cells that through contraction or relaxation give the impression of a colour change). This shark grows to 1.5 meters (5 feet) in length. It is primarily nocturnal.
This shark is a scavenger and opportunistic feeder, but regularly feeds upon crabs, lobster and shrimp.
The smooth dogfish is a viviparous shark giving birth to a litter of 10 to 20 pups. Gestation is 10 months long and the young are usually delivered in the summer months. The pups are 34 to 39 cm (13 to 15 inches) at birth. Sexual maturity is reached when individuals reach 85 cm (33 inches) in length.
This shark commonly lives in bays and inshore waters. It prefers waters less than 18 meters (60 feet) deep. The smooth dogfish is a migratory species that moves north and south with the seasons.
This species of shark occurs in the western Atlantic Ocean. It ranges from the Bay of Fundy to Uruguay. It is a common shark in the waters off Cape Cod to Delaware Bay, and overwinters from Chesapeake Bay to South Carolina. It is rare in Canadian waters and the Bay of Fundy represents the northern most part of its range.

Silky Shark


The silky shark, Carcharhinus falciformis, is a large pelagic shark of tropical and warm temperate seas.
This species is found worldwide in tropical and warm temperate (> 23 °C) seas. It is usually pelagic, but sometimes approaches the coast, especially at remote offshore islands. It is found to depths of at least 500 m.
This shark has a large 'typical' shark body, slender with 'silky' smooth skin. It is brown-grey dorsally and white below with no special markings. It can be distinguished from other sharks by the second dorsal fin, which has a very long free tip at the rear, about two and a half times the fin height. The first dorsal fin is also farther back than on any other carcharhiniform, beginning behind the pectoral fins.[1]
The maximum size is 3.3 m, but the length is usually not more than 2.4 m.
The silky shark is a predator. It feeds mainly on inshore and pelagic bony fishes, but also eats squid and pelagic crab.

Shortfin Mako Shark


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 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.
The shortfin mako can grow to lengths of 3.9 meters (13 feet). There is still some uncertainty about its life-span, but it is suspected to reach ages of between 11-23 years.
As one of the fastest sharks in the ocean, this powerful shark can attain burst swimming speeds of up to 35 km/h (22 mph) and can leap clear of the water to heights of up to 6 meters (20 feet). These qualities have made this species a sought after sport fish in some parts of its range.
The shortfin mako feeds mainly upon bony fishes including mackerels, tunas, bonitos and swordfish, but may also eat other sharks, porpoises and sea turtles.
Reproduction
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.
Habitat
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.
Range
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.

School Shark


School Shark :
Size: Up to 6ft long
Weight: Unknown
Food Sources: Bony fish
Habitat: Deep waters 550 m (1,800 ft)
Locations: Western Atlantic: southern Brazil to Argentina
Interesting Facts: None