Dolphins

Dolphins can be taught amazing tricks. That is why they are considered clever and intelligent. A dolphin’s brain is almost as large as a human’s. This is another reason they are thought to be clever. People say they can tell other dolphins apart by their whistles. But greylag geese also recognize one another by the sounds they make. Others believe dolphins can recognize themselves in a mirror. But people believe the same about Barbary macaques. We probably still know far too little about dolphins to really say anything about their intelligence.

One thing is certain: dolphins are easy to train. They leap high and swim on their backs because their trainers tell them to. They move backwards and appear to stand on their tail flukes. On command, they shoot through the water at high speed and spin in the air as they jump.

The animals are used in “dolphin shows” to demonstrate what they have been taught. The military uses dolphins to lay or defuse dangerous sea mines. In all these cases, the animals are kept in large tanks that offer them far less space than the open sea.

Dolphin calves are born live. They are mammals, because their mothers feed them breast milk during their first weeks of life. Fish, on the other hand, hatch from eggs and fend for themselves from the first day of life. Fish can change their body temperature to match the temperature of the water. Dolphins, on the other hand, maintain a constant body temperature. And like all mammals, they breathe with lungs, not gills like fish. Newborn dolphins can swim straight away. A mother gives birth to only one calf at a time, and it stays with her for up to six years. Calves do not have lips with which to suckle, so the mother squirts fatty milk from her mammary glands into their mouths. The young begin searching for food on their own after a few months.

There are about 40 different species of dolphins, including the common bottlenose dolphin, the false killer whale and pygmy killer whale, and the common dolphin, which is also found in the Mediterranean. The false killer whale is also called an orca. Dolphins grow to about 1.5 to 4 meters long. The orca, the largest member of the group, can reach a length of up to 8 meters. Most species have a dark gray back and a lighter underside; others are black and white. Dolphins can live for about 20 to 40 years. They are fast swimmers, reaching speeds of about 50 km/h while remaining incredibly agile. Because dolphins have lungs, they need to come to the surface regularly to breathe. Even so, they can dive to depths of up to 300 meters and stay underwater for about 15 minutes.

Dolphins breathe through a nostril on the top of their head. When they surface, like whales, they first blow out their stale air. That’s why the nostril is also called a blowhole.

Dolphins have excellent hearing and can see very well underwater. But they mainly use sound waves to find their way around. The so-called “melon,” located on the upper part of the head, emits sound waves. When these waves hit rocks, ships or prey, they bounce back and are detected by the dolphin. This process is called echolocation.

Dolphins live in groups. Hundreds of animals gather in places where food is particularly plentiful. Sick or injured dolphins are supported by their companions. Dolphins communicate through clicks and whistles, chatter and other sounds. They sleep by letting one half of their brain rest while the other half stays awake. One eye always remains open while they sleep, so they can detect predators. During sleep, the animals move very little.

Dolphins feed on smaller fish, squid and crustaceans. The killer whale, the largest dolphin, also hunts seals, small whale species and other smaller dolphins. Apart from the killer whale, dolphins have no dangerous predators.

They often leap out of the water and can perform acrobatic moves. The animals probably do this for fun, but their leaps can also help them swim faster. While in the air, they also look out for gulls, which show them where to find good feeding spots.

They can also use echolocation to navigate their surroundings and, above all, to find food. They hunt together, for example by circling a school of prey or driving it towards the coast into shallower water.