Dolphins are a group of aquatic mammals that emerged in a form similar to today's about 30 million years ago, during the Oligocene epoch, and are still alive today. Like whales, their closest modern terrestrial relative is the hippopotamus.
Dolphins vary in size from Maui's dolphin, at 1.7 meters in length and 50 kilograms, to the orca, reaching 9.5 meters and 10 tonnes. Various dolphin species exhibit sexual dimorphism, with males being larger than females. They have bodies extremely well adapted to aquatic life, featuring smooth, firm skin and a layer of blubber designed to retain body heat even in cold water. Thanks to these adaptations, some dolphins can briefly travel at speeds of up to 29 kilometers per hour and leap approximately 9 meters high. Dolphins are carnivores, feeding on fish and squid by using their conical teeth to capture prey. They possess highly developed hearing, which allows them to utilize a method of prey tracking known as echolocation. This method involves the dolphin emitting high-frequency sounds that bounce off surrounding objects and return to the dolphin, providing information about their position and shape.
