Sharks

Blue Shark

Blue sharks are curious, open-ocean predators that live throughout the global ocean, from the tropics to cold temperate waters. They spend most of their lives far from the coast and are truly a pelagic species. The common name comes from the blue color of the skin, unique among the sharks. Blue sharks are light-bodied with long pectoral fins. Like many other sharks, blue sharks are countershaded: the top of the body is deep blue, lighter on the sides, and the underside is white. The male blue shark commonly grows to 1.82 to 2.82 m (6.0 to 9.3 ft) at maturity, whereas the larger females commonly grow to 2.2 to 3.3 m (7.2 to 10.8 ft) at maturity. Large specimens can grow to 3.8 m (12 ft) long. Occasionally, an outsized blue shark is reported, with one widely printed claim of a length of 6.1 m (20 ft), but no shark even approaching this size has been scientifically documented. Large specimens can grow to 3.8 m (12 ft) long. Occasionally, an outsized blue shark is reported, with one widely printed claim of a length of 6.1 m (20 ft), but no shark even approaching this size has been scientifically documented. Occasionally, a female in excess of 3 m (9.8 ft) will weigh over 204 kg (450 lb). The heaviest reported weight for the species was 391 kg (862 lb).The blue shark is also ectothermic and it has a unique sense of smell. he blue shark is an oceanic and epipelagic shark found worldwide in deep temperate and tropical waters from the surface to about 350 m (1,150 ft). In temperate seas it may approach shore, where it can be observed by divers; while in tropical waters, it inhabits greater depths. It lives as far north as Norway and as far south as Chile. Blue sharks are found off the coasts of every continent, except Antarctica. Its greatest Pacific concentrations occur between 20° and 50° North, but with strong seasonal fluctuations. In the tropics, it spreads evenly between 20° N and 20° S. It prefers water temperatures between 12 and 20 °C (54–68 °F), but can be seen in water ranging from 7 to 25 °C (45–77 °F).Records from the Atlantic show a regular clockwise migration within the prevailing currents. Squid are important prey for blue sharks, but their diet includes other invertebrates, such as cuttlefish and pelagic octopuses, as well as lobster, shrimp, crab, 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.Sharks have been observed and documented working together as a 'pack' to herd prey into a concentrated group from which they can easily feed. Blue sharks may eat tuna, which have been observed taking advantage of the herding behaviour to opportunistically feed on escaping prey. The observed herding behaviour was undisturbed by different species of shark in the vicinity that normally would pursue the common prey. The blue shark can swim at fast speeds, allowing it to catch up with prey easily. Its triangular teeth allow it to easily catch hold of slippery prey. Young and smaller individuals may be eaten by larger sharks, such as the great white shark and the tiger shark. Killer whales have been reported to hunt blue sharks. This shark may host several species of parasites. For example, the blue shark is the definitive host of the tetraphyllidean tapeworm, Pelichnibothrium speciosum. It becomes infected by eating intermediate hosts, probably opah and/or longnose lancetfish. Northern elephant seals have been observed to feed on blue sharks.

Bonnethead Shark

The bonnethead shark or shovelhead (Sphyrna tiburo) is a small member of the hammerhead shark genus Sphyrna, and part of the family Sphyrnidae. It is an abundant species on the American littoral, is the only shark species known to display sexual dimorphism in the morphology of the head, and is the only shark species known to be omnivorous. Sphyrna derives from the Greek word for 'hammer', referring to the shape of this shark's head; tiburo derives from the Spanish word 'tiburón', meaning 'shark'. Characterized by a broad, smooth, spade-like head, it has the smallest cephalofoil (hammerhead) of all Sphyrna species. The body is grey-brown above and lighter on the underside. Typically, bonnethead sharks are about 2–3 ft (0.61–0.91 m) long, with a maximum size of about 5 ft (150 cm). Females tend to be larger than males. This species occurs off the American coast, in regions where the water is usually warmer than 70 °F (21 °C). It ranges from New England, where it is rare, to the Gulf of Mexico and Brazil, and from southern California to northern Peru. During the summer, it is common in the inshore waters of the Carolinas and Georgia; in spring, summer, and fall, it is found off Florida and in the Gulf of Mexico. In the winter, the bonnethead shark is found closer to the equator, where the water is warmer. It frequents shallow estuaries and bays over seagrass, mud, and sandy bottoms.

Bronze Whaler Shark

The copper shark, bronze whaler, or narrowtooth shark, is a species of requiem shark, familyCarcharhinidae, and the only member of its genus mainly found at temperate latitudes. It is distributed in several separate populations in the northeastern and southwestern Atlantic, off southern Africa, in the northwestern and eastern Pacific, and around Australia and New Zealand, with scattered reports from equatorial regions. This species can be found in brackish rivers and estuaries, shallow bays and harbors, to offshore waters 100 m deep or more. The copper shark is the only member of its genus primarily found in temperate rather than tropical waters, in temperatures above 12 °C (54 °F). It is widely distributed but as disjunct regional populations with little to no interchange. e copper shark has a slender, streamlined body with a slightly arched profile just behind the head. The snout is rather long and pointed, with the nostrils preceded by low flaps of skin. The round, moderately large eyes are equipped with nictitating membranes (protective third eyelids). The mouth has short, subtle furrows at the corners and contains 29–35 upper tooth rows and 29–33 lower tooth rows. The teeth are serrated with single narrow cusps; the upper teeth have a distinctive hooked shape and become more angled towards the corners of the jaw, while the lower teeth are upright. The upper teeth of adult males are longer, narrower, more curved, and more finely serrated than those of adult females and juveniles. The five pairs of gill slits are relatively long.

Fox Shark

The Thresher Shark is also known as the Alopias Vulpinus or Fox Shark. Its name comes from the sharks unusually large tail (caudal fin), which is in most cases, as long as the shark itself.Although occasionally sighted in shallow, inshore waters, thresher sharks are primarily pelagic; they prefer the open ocean, characteristically preferring water 500 metres (1,600 ft) and less.Common threshers tend to be more prevalent in coastal waters over continental shelves. Common thresher sharks are found along the continental shelves of North America and Asia of the North Pacific, but are rare in the Central and Western Pacific. In the warmer waters of the Central and Western Pacific, bigeye and pelagic thresher sharks are more common. A thresher shark was seen on the live video feed from one of the ROVs monitoring BP's Macondo oil well blowout in the Gulf of Mexico. This is significantly deeper than the 500m previously thought to be their limit. A bigeye has also been found in the western Mediterranean, and so distribution may be wider than previously believed, or environmental factors may be forcing sharks to search for new territories.

Leopard Shark

The leopard shark is one of the most common sharks along the coast of California. It’s a beautiful, slender fish with silvery-bronze skin, patterned with dark ovals that stretch in a neat row across its back. It is found along the Pacific coast of North America, from the U.S. state of Oregon to Mazatlán in Mexico. The leopard shark has a moderately stout body, with a short, rounded snout. There are well-developed, triangular flaps of skin in front of the nares. The eyes are large and oval, with a nictitating membrane (a protective third eyelid). The line of the mouth is strongly curved. There are furrows at the corners of the mouth extending onto both jaws, with those on the lower jaw almost long enough to meet at the midline. The tooth rows number 41–55 in the upper jaw and 34–45 in the lower jaw; each tooth has a slightly oblique, smooth-edged cusp in the center and 1–2 small cusplets on either side. These teeth are arranged into a flat, 'pavement'-like surface with overlapping ridges. The large first dorsal fin is positioned about halfway between the pectoral and pelvic fins; the second is almost as large as the first and much larger than the anal fin. The pectoral fins are wide and triangular. The lower lobe of the caudal fin is well-developed in adults but less than half the length of the upper lobe, which has a strong ventral notch near the tip.The coloration is unique, consisting of prominent black 'saddles' and large black spots running along the back, on a silvery to bronzy gray background. Adult sharks often have more spots and saddles with lighter centers compared to juveniles. The underside is whitish and plain.The average length of a leopard shark is 1.2–1.5 m (3.9–4.9 ft). Rarely males may grow to 1.5 m (4.9 ft) and females 1.8 m (5.9 ft), and there is a record of an exceptional female that measured 2.1 m (6.9 ft) long. The heaviest known leopard shark weighed 18.4 kg (41 lb).

Mako Shark

The shortfin mako shark (Isurus oxyrinchus), also known as the blue pointer or bonito shark, is a large mackerel shark. It is commonly referred to as the mako shark, as is the longfin mako shark (Isurus paucus).The shortfin mako can reach a size of 4 m (13 ft) in length. The species is classified as Endangered by the IUCN. The shortfin mako shark is a fairly large species of shark. Growth rates appear to be somewhat accelerated in comparison to other species in the lamnid family.An average adult specimen measures around 3.2 m (10 ft) in length and weighs from 60–135 kg (132–298 lb). The species is sexually dimorphic, with females typically larger than males. Large specimens are known, with a few large, mature females exceeding a length of 3.8 m (12 ft) and a weight of 570 kg (1,260 lb). The shortfin mako inhabits offshore temperate and tropical seas worldwide. The closely related longfin mako shark is found in the Gulf Stream or warmer offshore waters (for ex., New Zealand and Maine). It is a pelagic species that can be found from the surface to depths of 150 m (490 ft), normally far from land, though occasionally closer to shore, around islands or inlets. One of the very few known endothermic sharks, it is seldom found in waters colder than 16 °C (61 °F). 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 neither abundant nor rare. Swordfish are good indicators of shortfin mako populations, as the former are a source of food and prefer similar environmental conditions.

Spiny Dogfish

The spiny dogfish, spurdog, mud shark, or piked dogfish is one of the best known species of the Squalidae (dogfish) family of sharks. The spiny dogfish has dorsal fins, no anal fin, and white spots along its back. The caudal fin has asymmetrical lobes, forming a heterocercal tail. The species name acanthias refers to the shark's two spines. These are used defensively. If captured, the shark can arch its back to pierce its captor with spines near the dorsal fins that secrete a mild venom into its predator.This shark is known to hunt in packs that can range up into the thousands. They are aggressive hunters and have a sizable diet that can range from squid, fish, crab, jellyfish, sea cucumber, shrimp and other invertebrates. Males mature at around 11 years of age, growing to 80–100 cm (31–39 in) in length; females mature in 18–21 years and are slightly larger than males, reaching 98.5–159 cm (38.8–62.6 in).Both sexes are greyish brown in color and are countershaded. Males are identified by a pair of pelvic fins modified as sperm-transfer organs, or 'claspers'. The male inserts one clasper into the female cloaca during copulation.

Whale Shark

Whale sharks inhabit warm waters around the world. They are found in the western Atlantic Ocean from the coast of New York in the United States to central Brazil, including the Gulf of Mexico and the Caribbean Sea. In the eastern Atlantic they occur from the coasts of Senegal, Mauritania, and Cape Verde to the Gulf of Guinea. Whale sharks also inhabit the Indian Ocean and the western and central Pacific. They have appeared off the coast of South Africa and in the Red Sea, as well as near Pakistan, India, Sri Lanka, Malaysia, Thailand, China, Japan, the Philippines, Indonesia, Papua New Guinea, Australia, New Caledonia, and Hawaii. In the eastern Pacific they can be found from southern California in the United States to northern Chile. The whale shark is enormous and reportedly capable of reaching a maximum length of about 18 metres (59 feet). Most specimens that have been studied, however, weighed about 15 tons (about 14 metric tons) and averaged about 12 metres (39 feet) in length. The body coloration is distinctive. Light vertical and horizontal stripes form a checkerboard pattern on a dark background, and light spots mark the fins and dark areas of the body. The head is broad and flat, with a somewhat truncated snout and an immense mouth. Several prominent ridges of hard tissue, often called keels, extend horizontally along each side of the body to the tail. There are five large gill slits on each side of the head region, just above the pectoral fins. Special spongy tissue inside the gill slits that is supported by the shark’s gill arches forms a unique filter used in feeding. A short, rudimentary sensory organ called a barbel hangs from each nostril. The shark has a large front dorsal (top) fin and smaller rear dorsal and anal fins.

White Shark

While the shark in Jaws was inspired by a great white shark in New Jersey, the legendary fish is far less fearsome in reality. As scientific research on these elusive predators increases, their image as mindless killing machines is beginning to fade. Found in cool, coastal waters around the world, great whites are the largest predatory fish on Earth. They grow to an average of 15 feet in length, though specimens exceeding 20 feet and weighing up to 5,000 pounds have been recorded. They have slate-gray upper bodies to blend in with the rocky coastal sea floor, but they get their name from their white underbellies. They're streamlined, torpedo-shaped swimmers with powerful tails that can propel them through the water at speeds of up to 15 miles per hour. They can even leave the water completely, breaching like whales when attacking prey from underneath. Highly adapted predators, their mouths are lined with up to 300 serrated, triangular teeth arranged in several rows, and they have an exceptional sense of smell to detect prey. They even have organs that can sense the tiny electromagnetic fields generated by animals. Their prey includes other sharks, crustaceans, molluscs, and sea birds. Larger whtie sharks will also prey on sea lions, seals, and small toothed whales like orcas. The species has even been seen feeding on dead whales.

Whitetip Shark

The oceanic whitetip shark (Carcharhinus longimanus), also known as Brown Milbert's sand bar shark, brown shark, lesser white shark, nigano shark, oceanic white-tipped whaler, and silvertip shark, is a large pelagic requiem shark inhabiting tropical and warm temperate seas. Its stocky body is most notable for its long, white-tipped, rounded fins. Though slow-moving, they are opportunistic and aggressive, and are reputed to be dangerous to shipwreck survivors. Recent studies show steeply declining populations because its large fins are highly valued as the chief ingredient of shark fin soup, and as with other shark species, the whitetip faces mounting fishing pressure throughout its range. The oceanic whitetip is found globally in deep, open oceans, with a temperature greater than 18 °C (64 °F), although exceptionally it occurs in water as cold as 15 °C (59 °F).It prefers waters between 20 and 28 °C (68–82 °F) and tends to withdraw from areas when temperatures fall outside of these limits. It was once extremely common and widely distributed, and still inhabits a wide band around the globe; however, recent studies suggest that its numbers have drastically declined. An analysis of the US pelagic longline logbook data between 1992 and 2000 (covering the Northwest and Western Central Atlantic) estimated a decline of 70% over that period. It is found worldwide between 45°N and 43°S latitude. In September 2004, a 2.3 m (7.5 ft) vagrant oceanic whitetip shark was seen in the brackish waters of Gullmarsfjorden in Sweden; it died shortly after.[8][9] This is the only North European record and far north of its usual range limit. Whitetip sharks' most distinguishing characteristics are its long, wing-like pectoral and dorsal fins.The fins are significantly larger than most other shark species, and are conspicuously rounded. The shark's nose is rounded and its eyes are circular, with nictitating membranes.