Thursday, January 24, 2008
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 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.
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.
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.They are also frequently spotted around other Coral Reefs along the West Malaysian coast including Kapas Island and Redang Island.
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)  and weigh 385 to 909 kg (850 to 2000 lb). 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" and "the wastebasket of the sea".
The tiger shark is second only to the bull shark in number of recorded human fatalities  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.  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.
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.
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 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.