Very long, cylindrically shaped (fusiform) trunk. Very pointed snout, with a large, subterminal mouth. Big eyes. Extremely large gill slits that nearly extend ventrally and dorsally around the head. First dorsal fin large, erect and triangular. Its origin is well behind the free ends of the pectoral fins. Second dorsal fin much smaller than first one. Lunate caudal fin with depressed caudal peduncle and strong lateral keels.
Coloration
Nearly black.
Distribution
Wide ranging in temperate and cold (subpolar) seas. Western Atlantic: New Foundland to Florida, southern Brazil and Argentina. Eastern Atlantic: Iceland, Norway, North Sea. Mediterranean. South Africa. Western Pacific: Japan, Korea, China, Australia (New South Wales, Victoria, Western Australia), Tasmania, New Zealand. Eastern Pacific: Gulf of Alaska to Gulf of California, Ecuador, Peru, Chile.
Biology
Basking sharks live over the continental shelves in pelagic but not oceanic waters. Highly migratory, with seasonal appearances in certain localities and subsequent disappearances. Can be found alone and in aggregations (up to 100 animals). Basking sharks are probably the original subject of the "sea monster" stories since they prefer to swim directly under the water surface (plankton feeders) with their dorsal and caudal fin penetrating the surface, and sometimes follow each other. Basking sharks are passive feeders and do not actively suck in water as does the. They are able to filter about 2000 tons of water per hour. Gill rakers are shed on a yearly basis and then said to hibernate (although proof is still lacking) in deeper water. Basking sharks are nearly positively buoyant due to their large livers (up to 25 % of their total weight) that are filled with certain oils (squalene).
Diet
Plankton.
Size
Maximum total length about 1200 cm, average size between 900 cm and 1000 cm. Rarely caught under 300 cm (smallest animal ever caught was 170 cm).
Reproduction
Aplacental viviparous (ovoviviparous). Probably with an uterine cannibalism (ooph. Size at birth unknown (probably around the 170 cm mark). Unknown litter size. Pregnant females are hardly caught. Males seem to reach sexual maturity between a size of 400 cm to 500 cm.
Similar Species
None.
Vulnerability
Category:Endangered (EN) Criteria:A2bd Last evaluated:2021 Trend:
