A group of whales is usually called a pod, but other terms for a group of whales include a gam, a herd or a school. A pod usually includes whales that are either related to each other or whales that have formed friendships with each other. Pods are made up of anywhere from two to 30 whales or more.
Smaller-toothed whale species tend to form larger pods which helps to protect them from predators. Larger baleen whales are not as afraid of predators, so their pods tend to be smaller; some of these whales even prefer to travel on their own. Female whales are more likely to live in pods with their own children and other female whales and their children.
In subtropical and tropical waters, female sperm whales rear their young in pods of 15 to 20, with males moving from group to group. Gray whales travel in pods of various sizes during winter migration, when they leave the coast of Alaska for the tropical waters off the shore of Mexico. Killer whales form pods of up to 40 to hunt, employing a technique some scientists liken to that used by wolf packs.