Dolphins are very intelligent animals with big, complex brains that allow them to communicate, learn quickly, and hunt cooperatively in groups. They live in pods in oceans around the world, and while some species prefer warmer waters, others like pink dolphins live in rivers like the Amazon. Dolphins care for their young for up to six years, communicating through clicking and whistling, and have lifespans around 25 years. However, they are now endangered due to threats like fishing nets, pollution, climate change, and habitat loss.