Bottlenose dolphins are a highly intelligent species and use sound both for communication and to hunt for food. They swim at speeds up to 35 km/h (22 mph) and dive as deep as 915 m (3000 ft.). They have a thick layer of blubber which helps them maintain their body heat and protects them from predators such as killer whales and large sharks. They have sensitive, smooth skin that flakes off and gets replaced every few hours.
Dolphins aren’t involuntary breathers like humans. They must consciously swim to the surface to take a breath. This means they can never fully sleep. One side of their brain must always be active so that they remember to breathe.
They also have an excellent sense of hearing. Sounds travel through their lower jaw to their inner ear. Bottlenose dolphins communicate with each other using a collection of chirps, whistles, and clicks. They create these sounds using nasal sacs in their heads and their blowholes. Each dolphin has a signature whistle used to identify itself. When lost or isolated, a dolphin uses the signature whistle to call out to the group.
Bottlenose dolphins use echolocation when hunting for fish, squid, and crustaceans. They consume 8-15 kg (15-30 lbs.) food per day. Although they sometimes hunt independently, they also cooperate in groups to capture prey.