OT Staff & Waquar Habib
The heaviest animal ever, blue whales can weigh up to 190 tonnes and measure nearly 30 metres, with a heart as large as a small car.
The largest toothed whale and deep-diving mammal, sperm whales can weigh around 57 tonnes, and are known for their heads filled with spermaceti oil.
The world’s largest fish, the whale shark reaches weights of up to 19–20 tonnes, feeding mainly on plankton.
The heaviest land mammal, males can weigh up to 6–10 tonnes, with long tusks and characteristic large ears aiding heat regulation.
A slightly smaller species, Asian elephants weigh up to 8 tonnes, and are distinguished by smaller ears and one finger-like trunk tip.
Weighing up to 3–4.5 tonnes, white rhinos are among the heaviest terrestrial mammals and are recognised by their broad mouths and thick skin.
Heavy river-dwellers, hippos weigh around 2–4.5 tonnes and are known for their massive canines and semi-aquatic lifestyle in African rivers.
These sizable marine mammals can weigh approximately 4 tonnes, with males significantly larger than females, and come ashore to breed.
The tallest land animal, giraffes also rank among the heaviest, weighing up to 1.4 tonnes with long necks and spotted coats.
The largest living reptile, saltwater crocodiles weigh up to 1.1–1.5 tonnes and inhabit coastal and riverine regions across parts of Asia and Australia.