Dolphins

Dolphins are a widely distributed and diverse group of aquatic mammals. They are part of the family Delphinidae, which is a branch of the infraorder Cetacea. Dolphins are known for their high intelligence, complex behaviors, and acrobatic abilities. There are 40 extant species of dolphins, which are found in every ocean of the world and in some major river systems.

Anatomy and Physiology

Dolphins have streamlined bodies and two limbs that are modified into flippers. They use their conical shaped teeth to capture fast moving prey. They have a dorsal fin for stabilization and a powerful tail fin that propels them through the water. Dolphins are capable of rapid swimming. The largest dolphin, the orca or killer whale, can reach speeds of up to 56 km/h (34.8 mph).

Dolphins are also known for their extraordinary intelligence. Their brain size compared to their body size is second only to humans. Dolphins are capable of complex problem solving and social interaction. They are known to use tools, exhibit cultural behavior, and have sophisticated methods of communication.

Behavior

Dolphins are highly social animals, often living in pods of up to a dozen individuals. In places with a high abundance of food, pods can merge temporarily, forming a superpod; such groupings may exceed 1,000 dolphins. They communicate using a variety of clicks, whistle-like sounds, and other vocalizations. Dolphins also use nonverbal communication by means of touch and body postures.

Dolphins are known to engage in acts of aggression towards each other. The older a male dolphin is, the more likely his body is to be covered with bite scars. Male dolphins engage in acts of aggression apparently for the same reasons as humans: disputes between companions and competition for females. Acts of aggression can become so intense that targeted dolphins sometimes go into exile after losing a fight.

Conservation

Many species of dolphins are threatened by human activities. Dolphins are often caught in fishing nets, and their natural habitats are being destroyed by pollution and coastal development. Conservation efforts are in place globally to protect populations of dolphins, including marine protected areas and regulations on fishing practices.

Cultural Importance

Dolphins have been featured in human culture for centuries. They are common in Greek mythology, and are seen as symbols of protection and good luck. Today, dolphins are featured in a variety of media and are popular attractions in aquariums and marine parks.

See Also

• Cetacean intelligence
• Cetacean stranding
• List of cetaceans