Hobbies And Interests
Types of Dolphins
There are more than 30 different types of ocean dolphin. The bottlenose is the one often seen in films and photographs. These dolphins look as if they are smiling because of the shape of their jaws. The average bottlenose is about 10 to 14 feet long and can weigh up to 1,500 lbs. The largest dolphin is the orca, also known as the killer whale, which can be about 30 feet long and weigh an average of 8,000 to 12,000 lbs. Despite its name, the killer whale does not by nature attack humans. It's the kind of dolphin that performs in shows at Sea World. There are five types of river dolphins that live in some of the largest rivers in Asia and South America. River dolphins have a longer nose/snout than ocean dolphins and the Amazon River dolphin in South America is pink.
Dolphin Bodies
Dolphins are mammals and cannot breathe under water. They breathe through a blowhole in the top of their head and hold their breath in the same way humans do when they want to swim under water. Some dolphins can hold their breath for up to 15 minutes. To sleep, they rest at the surface of the water or swim slowly under water and come up for air. Some species can swim up to 25 mph. They mostly use their tail to move and their fins to steer. Dolphins have fantastic hearing, but hardly any sense of smell.
Lifestyle
Dolphins swim in groups of 12 known as pods. These pods often join with other pods to form herds of hundreds of dolphins. Dolphins use a technique called echolocation to work out where there is food or danger. The dolphin will make a sound that travels through the water until it hits an object and bounces back. This allows the dolphin to work out how large and far away the object is. Dolphins eat almost all types of fish, which they swallow whole.
Dolphins and Humans
Dolphins are often seen approaching and swimming alongside boats and can be playful with humans. While some people believe swimming with dolphins will heal them, humans as a whole are the biggest threat to dolphins in the wild. Noise pollution from ships makes it hard for dolphins to use echolocation to track down food. The chemical pollution humans leave in the oceans is dangerous for dolphins, and some dolphins accidentally get caught in the large nets used for commercial fishing.