Hyenas are considered one of the most intelligent carnivores, and they have a very complex social structure. Their brains are about the size of those of a domestic cat, and they are able to solve problems and think ahead. The spotted hyena is particularly known for its intelligence, and it has even been observed using tools – such as rocks to break open bones – in order to get at the marrow inside. Hyenas also work together to steal food from other predators or scavenge on carcasses. They are often able to outwit their prey or rivals, making them very successful predators.