The emperor penguin is the tallest and heaviest species of penguin, and is native to Antarctica. Both males and females of the species are of similar height (122cm) and weight (22-45kg). Its diet primarily of fish but also includes crustaceans such as krill and cephalopods such as squid. When hunting, the species can remained submerged for up to 18 minutes, diving to a depth of 535m (1755ft). To allow it to function at low oxygen levels, it has evolved solid bones to reduce barotrauma and the ability to reduce its metabolism.