Dolphins Reading Comprehension Lesson

Life in the Ocean

Dolphins are marine mammals that live in oceans and seas all over the world, and some species also live in rivers. There are nearly 40 species of dolphins, ranging in size from the small Maui’s dolphin, which is less than five feet long, to the orca, or killer whale, which can grow to more than 30 feet. The most familiar species is the bottlenose dolphin, the kind most often seen in aquariums and on television. Dolphins breathe air through a blowhole on top of their heads and must surface regularly to breathe.

Dolphins are warm-blooded and give birth to live young, which they nurse with milk — just like land mammals. A baby dolphin, called a calf, stays close to its mother for several years, learning the skills it needs to survive. Dolphins are highly social animals and live in groups called pods, which can range from a few individuals to hundreds of dolphins. Within a pod, dolphins cooperate to find food, protect one another from predators, and care for young calves.

Dolphins are carnivores — they eat fish, squid, and other sea creatures. Bottlenose dolphins are known to work together when hunting: they herd schools of fish into tight balls near the water’s surface, then take turns charging through to grab fish. In some coastal areas, dolphins have even been observed cooperating with human fishermen, driving fish into nets in exchange for a share of the catch — a behavior that has been passed down through generations of dolphins in the same communities.

Intelligence and Communication

Dolphins are among the most intelligent animals on Earth. They have large, complex brains relative to their body size — a trait associated with high intelligence in many species. Dolphins can recognize themselves in mirrors, a sign of self-awareness that only a handful of animal species have demonstrated, including great apes, elephants, and humans. They can learn complex sequences of instructions, use tools, and solve problems in ways that suggest genuine reasoning.

One of the dolphin’s most remarkable abilities is echolocation. Dolphins produce clicks and high-pitched sounds from an organ in their forehead called the melon. These sounds travel through the water, bounce off objects, and return to the dolphin as echoes. By analyzing the returning echoes, a dolphin can determine the size, shape, distance, speed, and even the internal structure of objects — all in the dark or in murky water where vision is limited. Echolocation is so precise that dolphins can detect objects the size of a golf ball from 70 meters away.

Dolphins also communicate with each other using a wide range of whistles, clicks, and body movements. Each dolphin develops a unique signature whistle — much like a name — that other dolphins use to identify it. Dolphins have been observed calling each other by name, a form of referential communication that was once thought to be unique to humans. Scientists continue to study dolphin communication and intelligence, and many researchers believe we have only begun to understand how complex dolphin social and cognitive lives really are.

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