Its flippers are small and slightly tapered while the tail lobes (flukes) are broad and can measure 16ft (5 m) from tip to tip. Adult males reach up to 59 ft (18 m) in length and can weigh 45 tons (40,800 kg). The females are much smaller at 36 ft (11 m), weighing a maximum of 14 tons (12,700 kg). Sperm Whales eat thousands of pounds of fish and squid a day and can dive as deep as 3,280ft (1,000 m). Males sexually mature at around 10 years, but do not appear to take part in breeding until their late twenties. Females are sexually mature between 7 and 13 years. The gestation period (pregnancy) is a long 14 to 16 months and the calves nurse for at least two years. Sperm Whales travel in groups (pods) of females and young, with the males visiting for only a few hours at a time. These groups usually have 10 to 20 members, and seem to communally care for the young.