So, there are 32 species of dolphins (plus 5 species of closely related river dolphins) and 6 species of porpoise. 'Killer whales', or orcas, are the largest. Hector's dolphins are the smallest. The most well known is the bottlenose, and the rarest is a subspecies of the Hector's dolphin known as the Māui dolphin. the bottlenose is one of the friendliest to humans, as the species is usually found near cities. Although they seem friendly, dolphins can be deadly. When threatened by sharks, (which are their only natural predators), they will jab at it until it dies. Aggressive dolphins or agitated ones will also attack humans in this way. Sharks will attack lone dolphins, but often avoid pods. Fun Fact: An extremely large pod of dolphins is a superpod.
When dolphins are babies, they have hair. Some retain that hair around their blowholes, even as adults. As babies, dolphins are basically paler versions of the parents. Orca babies stay with their parents for life. Dolphins don't actually chew their food, but instead break it into pieces and swallow it whole. Their teeth are cone shaped. The four river dolphin species inhabit the rivers of Asia, and are known as the Boto.
