Sharks
Whale shark, great white, hammerheads and the bull shark of rivers. 13 fish on EveryFish so far.
Sharks are cartilaginous fish: their skeletons are made of cartilage, not bone, their skin is covered in tooth-like scales and they have five to seven gill slits on each side. There are more than 500 species, from the dwarf lanternshark, which fits in a hand, to the whale shark, the largest fish alive. Sharks have swum the seas for more than 400 million years, longer than trees have grown on land.
How sharks live
Most sharks are predators, finding prey by smell, by the pressure waves their lateral line picks up and, at close range, by the weak electric fields living animals give off, sensed through pores on the snout. Not all hunt big prey: the whale shark, basking shark and megamouth filter plankton. Sharks grow slowly, mature late and have few young, often after a long pregnancy. The bull shark can live in fresh water and swims far up rivers, and the rare Ganges shark lives in the rivers of the Indian delta.
Sharks and people
Sharks are caught for their meat, liver oil and fins, which are used in shark fin soup, and very many die as bycatch. A 2021 study found that more than a third of all shark and ray species are threatened with extinction, mainly from overfishing. India is among the largest shark-catching countries, and in 2001 the whale shark became the first fish protected under India's Wild Life (Protection) Act. Shark bites on people are rare: a few dozen unprovoked bites are recorded worldwide each year.
Famous shark fish
Still to be written: Scalloped hammerhead, Bull shark, Tiger shark, Greenland shark, Ganges shark.
Further reading
Photo credits on this page
The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.
- Great white shark: Sharkdiver.com, Public domain, source
- Whale shark: User:Zac Wolf (original), en:User:Stefan (cropping), CC BY-SA 2.5, source
- Basking shark: Greg Skomal / NOAA Fisheries Service, Public domain, source