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Hammerhead Sharks
Appearance
Large, with a broad, narrow-bladed head. Anterior margin of "hammer" is very broadly arched in adults, with a prominent median indentation.
Distribution
Nearly circumglobal in tropical, subtropical and warm-temperate waters.
Biology
Probably the most abundant hammerhead species in coastal waters. Can even occur in river mouths and estuaries.
Feeding
Fishes (e.g. sardines, herrings, anchovies), invertebrates, mainly cephalopods), small sharks.
Size
Average size between 250 cm and 300 cm, maximum total length about 370 cm to 420 cm.
Reproduction
Viviparous, with yolksac-placenta (gives birth to live young). Size at birth between 40 cm and 55 cm. Gestation period lasts between 9 and 10 months. |
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Angel Sharks
The only sharks that cna bite their own tail. Often mistaken for rays. They have a brown and cream print. They occur in Lanzarote during the winter months.
Appearance
Bizarre-shaped shark. Flattened, ray-like form with free anterior pectoral lobes lateral to the gills. Eyes on dorsal surface, very big spiracles. Terminal mouth. Both dorsal fins are on caudal peduncle. Lower lobe of caudal fin is longer than the upper one.
Coloration
Uniformly light beige, no ocelli (dark dots).
Distribution
Western Atlantic: Massachusetts to Florida Keys, Gulf of Mexico, Caribbean.
Biology
Bottom-dweller, often in shallow water and buried in sand or mud. Found over the continental shelf and slope. A poorly known species.
Feeding
Molluscs, crustaceans, flounders, rays, bottom-dwelling fishes.
Size
Average size around 100 cm and 10 kg, maximum total length about 155 cm and 27kg.
Reproduction
Aplacental viviparous (ovoviviparous). Up to 16 pups per litter. Births seem to take place in spring and early summer. |
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Black Tip Sharks
Appearance
Shark with a long and pointed snout. Small eyes. Origin of the first dorsal fin usually over or slightly behind the insertion of the pectoral fins.
Coloration
Grey, grey-brown or bluish grey upper body, white ventral surface. Black tips usually present on pectoral fins, second dorsal fin, and ventral caudal lobe, and sometimes on pelvic fins. The tip of the anal fin is usually plain. A conspicuous white band on the flanks.
Distribution
Widespread in all tropical and subtropical waters over continental shelves. Western Atlantic: Massachusetts to southern Brazil. Bahamas, the Caribbean and Gulf of Mexico. Eastern Atlantic: Madeira, Mediterranean, Canary Islands to Zaire. Indo-Western Pacific: South Africa, Madagascar, and Red Sea to India, Sri Lanka, Pakistan, Thailand, China, the Philippines, Java, Borneo, Australia, New Guinea, New Caledonia. Central Pacific: Tahiti, Marquesas, Hawaiian Islands. Eastern Pacific: Southern Baja California to Peru, Galapagos Islands.
Biology
The blacktip shark is a common tropical and warm-temperate species of inshore and offshore pelagic waters. Commonly occurs in close inshore waters, off river mouths and estuaries, muddy bays, mangrove swamps, island lagoons and along drop-offs on coral reefs as well as far offshore. Rarely found in water deeper than 30 m. A very active, fast-swimming species that often occurs in large schools at the surface. It leaps out of the water, and like the related Spinner shark rotates around its axis before dropping back into the sea. This behavior is thought to be used by the shark while feeding on small schooling fishes. The shark launches itself vertically through the schools, spinning and snapping in all directions, and then breach the surface after the feeding run. Its social behavior makes it subject to feeding frenzies when a number of sharks compete for a highly concentrated food source.
Feeding
Primarily a fish-eater (sardines, herrings, anchovies) as well as small sharks such as smooth-hounds (Mustelus), sharpnose sharks (Rhizoprionodon), and a variety of young of larger shark species.
Size
Average size about 150 cm and 18 kg, maximum 255 cm.
Reproduction
Viviparous, with yolksac-placenta. 1 to 10 pups per litter, commonly 4 to 7. Size at birth about 40 to 70 cm. Gestation period is 10 to 12 months. Males mature between 135 and 180 cm, females mature between 120 and 190 cm. Estimated life span about 12 years. |
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Dusky Sharks
Appearance
Large, with a short, broadly rounded snout. Fairly large eyes. Origin of first dorsal fin is usually over or slightly in front of the rear tips of the pectoral fins. Low interdorsal ridge.
Coloration
Blue to grey upper body, white ventral surface. The tips of most fins are dusky, not black or white. Inconspicuous white band on the flanks.
Distribution
Eastern Atlantic: Gulf of Gascony, Madeira, Morocco, Mediterranean. Western Indian Ocean: South Africa. Western Pacific: Japan, Australia. Central Pacific: Hawaii. Eastern Pacific: Southern California, Gulf of California.
Biology
Commonly found inshore and offshore of warm-temperate and tropical area from the surface to 400 m depth. This species is strongly migratory in temperate and subtropical areas (North Pacific and North Atlantic).
Feeding
Feeds on a variety of reef, bottom and pelagic fishes, as well as angel sharks, saw sharks, spiny dogfishes, cat sharks, smooth-hounds, and other grey sharks (blacktip sharks, spinner sharks).
Size
Maximum size possibly over 400 cm (females), males reach about 340 cm.
Reproduction
Viviparous, with yolksac-placenta. 3 to 14 pups per litter. Size at birth between 70 and 100 cm. Births may occur over a long time span of several months in pupping areas, and have been reported as occurring from late winter to summer. Males mature at about 280 cm, females mature between 260 cm and 300 cm. Age at maturity about 6 years, expected life span at least 18 years. |
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With thanks and acknowledgemnt to http://www.shark.ch/index.html -
Shark Info / Dr. Erich K. Ritter - Shark Foundation
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