Size
Most easily distinguished by its size, Basking Sharks can reach up to a massive 11 m with adult size being up to 9 m for males and 10 m for females. Reaching 4.5 tonnes in weight, up to one quarter of this weight comprises of their liver which is very large and rich in oil.
Very few juvenile Basking Sharks have ever been recorded and so there is little information on the biology of young Basking Sharks. It is thought that at birth the sharks are between 1.5 – 2 m and maturity is reached at around 5 m for males and 8+ m for females (which can take about 12-16 years for both sexes).
Morphology & Colouration
Aside from their large size, Basking Sharks are characterised by their lunate tail, very large mouth, pointed nose and five huge gill slits which almost encircle the head. Other key identifying features are the strong lateral keels on the caudal peduncle (where the tail joins the body) the bristle-like gillrakers and rows of hundreds of minute teeth that fill the mouth. The mouth can be well over 1 metre wide in adult sharks.
Basking Sharks also have huge livers that account for up to 25% of their body weight and provides the shark with near neutral buoyancy.
One curious anomaly is the shape of the snout of juveniles which is long and hook like at birth and for the first year of life. It is believed that a hooked snout makes feeding in the womb and for the first few months of life easier by increasing water flow through the mouth.
Basking Sharks are typically grayish brown but can range through to slate grey or black on the dorsal surface. Irregular patches, patterns and streaks mark the animals flanks and fins while the ventral (underside) of Basking Sharks are predominantly lighter than the dorsal.
Biology
