Basking shark

Appearance

The two species can be easily distinguished by the basking shark's cavernous jaw, up to 1 m (3 ft 3 in) in width, longer and more obvious gill slits that nearly encircle the head and are accompanied by well-developed gill rakers, smaller eyes, much larger overall size, and smaller average girth. Great whites possess large, dagger-like teeth, while basking shark teeth are much smaller at 5–6 mm (0.20–0.24 in), and hooked. Only the first three or four rows of the upper jaw and six or seven rows of the lower jaw function. It is usually greyish-brown, with mottled skin, with the inside of the mouth being white in colour.

This species has the smallest weight-for-weight brain size of any shark, reflecting its relatively passive lifestyle.

The basking shark regularly reaches 7–8.5 m (23–28 ft) in length with some individuals reaching 9–11 m (30–36 ft).

Range and habitat

The basking shark is a coastal-pelagic shark found worldwide in boreal to warm-temperate waters. It is found from the surface down to at least 910 m (2,990 ft). The basking shark is a cosmopolitan migratory species found in all the world's temperate oceans.

Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.

Diet and breeding

Basking sharks are usually solitary, but during summer months in particular, they aggregate in dense patches of zooplankton, where they engage in social behaviour. Their seemingly useless teeth may play a role before birth in helping them feed on the mother's unfertilized ova (a behaviour known as oophagy).

Breeding frequency is thought to be two to four years. The basking shark has long been a commercially important fish as a source of food, shark fin, animal feed, and shark liver oil. Basking sharks are ovoviviparous: the developing embryos first rely on a yolk sac, with no placental connection.

In crisis

Typically, basking sharks reach 7.9 m (26 ft) in length, but large individuals have been known to grow more than 10 m (33 ft) long. Despite their large size and threatening appearance, basking sharks are not aggressive and are harmless to humans. Overexploitation has reduced its populations to the point where some have disappeared and others need protection.

Aside from direct catches, by-catches in trawl nets have been one of several threats to basking sharks. In June 2018, the Department of Conservation classified the basking shark as "Threatened - Nationally Vulnerable" under the New Zealand Threat Classification System.

CITES lists this taxon on Appendix II. Confirm the current appendix on the CITES checklist.

Basking shark is Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.

Sources

Written for this catalog from the English Wikipedia article on Basking shark, Wikidata item Q185260. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.