Physeter catodon, the sperm whale, is the largest toothed predator on Earth. Males can be over 18m long, weighing up to 50,000kg.Mature female sperm whales tend to live in social groups of up to 15 mature females and their offspring, whereas mature males live alone or in smaller groups.The sperm whale is listed as vunerable to extinction by the IUCN. Commercial whaling was the biggest threat to this species.