Largest animal omnivore

The world's largest animal omnivore (eating both animal and plant material) is the whale shark (Rhincodon typus), known to measure up to 18.8 m (61 ft 8 in) long and weigh up to 21.5 tonnes (47,400 lb). Traditionally, it was thought that this filter-feeding species fed exclusively upon krill – tiny marine crustaceans – making it carnivorous. However, research released by the journal Ecology in July 2022 involving analyses of whale-shark skin samples in relation to their microbiochemistry revealed that whale sharks off Western Australia's Ningaloo Reef were also consuming and digesting sizeable amounts of seaweed, e.g., brown sargassum. Indeed, researchers now speculate that the world's largest living fish may actually feed upon more plant material than krill.

Another part of this same study offered a further surprise – although the whale shark takes in large quantities of krill, the amount that it actually metabolizes is much smaller than originally expected. This offers additional support for the new belief that it did not evolve just to eat krill.

Prior to this new discovery featuring the whale shark, the world record holder for the largest omnivore was the Kodiak bear (Ursus arctos middendorffi), named after the Kodiak archipelago where it exists, off south-west Alaska, USA. Sometimes exceeding a total weight of 680 kg (1,499 lb) – the largest wild specimen on record weighed 751 kg (1,656 lb), and the largest captive specimen on record weighed 966 kg (2,130 lb) – the Kodiak bear exhibits an unequivocally omnivorous diet, ranging from salmon, small mammals, carrion and invertebrates to berries, seaweed and discarded food found in human garbage. Consequently, it still retains the record of largest omnivore on land.

Measurements of these elusive fish vary drastically from study to study, as well as between regions, but those measured to date have averaged 4–12 m (13 ft1 in–39 ft 4 in) long, with sexual maturity generally agreed to be reached at 9 m (29 ft 6 in). The largest scientifically documented specimen is a female whale shark that was caught in the Arabian Sea off Veraval in Gujarat, India, on 8 May 2001; she measured 18.8 m (61 ft 8 in) long.