Basking shark, Cetorhinus maximus, feeding in the surface waters off the coast of Cornwall, Southwest Britain. The gill rakers that extract planktonic animals from the water passing through its gaping mouth can be clearly seen. Basking sharks may reach 11m (36ft) in length and weigh 4.5 tons. In summer months basking sharks are frequently observed off the west coast of the UK. They generally arrive off the tip of Cornwall in may of early June, heading north through the Irish Sea to the waters off the west coast of Scotland.