About the wisdom of children (part three)
by firmm Team
Text: Edeltraud Konradt; Photos: firmm
Orcas eat dolphins
Not all Orcas eat dolphins. Orcas are divided into three cultures, they differ in body colouring, vocalisations, behaviour, and hunting techniques.
One cultural group of Orcas feeds mainly on meat, these Orcas live mainly in cold waters e.g. in the Arctic. On their menu are seals, elephant seals, other whales and also penguins. Because this Orca is itself a sea mammal and eats other sea mammals, it got the nickname killer whale. (the whale that kills).
The second culture group of Orcas feeds exclusively on fish.
The third is opportunistic, which means that it feeds on fish as well as other marine mammals. Seabirds are also on his menu. They are found off Iceland, for example.
When the dolphins are lying on the water surface, are they dead?
No: Dolphins sleep on the surface of the water or just below it, in the so-called half-side sleep: one eye and the opposite half of the brain sleep. The other half of the brain is awake and controls breathing, otherwise the animals would sink and drown. Dolphins and whales sleep differently, little is known about it. For example, a female Humpback Whale was sighted standing upside down with its fluke on the surface and sleeping for about 30 minutes at a time.
Sperm Whales - we could observe them here in the Strait of Gibraltar just in front of our boat. They also sleep vertically in the water, but with the fluke down and the head up and then they slowly sink into the depths. There are species that can "sleep" while swimming. Dolphins, however, are not night sleepers like humans, they sleep at all times, whenever they are tired. For example, they rest after hunting.
A dead whale or dolphin
When a dolphin or whale dies, its body sinks to the sea floor. There the body triggers a real feast. First it is ripped open by sleeper sharks or crabs. Then it is visited by scavenging deep-sea fish and worms, for whom the carcass is food. The bones are decomposed by micro-organisms and specialised bone worms, which takes months to years, depending on the size of the cetacean body.
Do dolphins have a name?
Dolphins are known to communicate with special sounds and/or songs. The songs of Humpback Whales are famous. Bottlenose Dolphins are known to call each other by name. They do not call a name like humans do but use a special sound that is only assigned to that particular animal and no other animal. Every dolphin recognises itself by its tone.
Beluga Whales are also called the canaries of the seas - their communication sounds are so beautiful for us humans. Like the chirping of canaries.
Do dolphins ever go somewhere else?
Whales and dolphins live in schools with strong social ties. The strongest bond is between a mother and her young. The dolphins' habitat is spread over the whole globe. From the Arctic to the Antarctic. Their migratory behaviour varies. Baleen Whales migrate from cold waters to warmer waters thousands of kilometres away to give birth and raise their offspring until the juveniles are strong enough to swim the long journey back.
In the case of dolphins, the schools are mixed differently, but so-called bachelor groups also form, which leave their original school and swim through the oceans. When they then meet a foreign group, they have a certain submissive behaviour and communication sounds to welcome the group. When they are accepted, they move on with the school, sometimes young males stay in the new one because they have found a female. The others in the bachelor group may take in bachelors from the school and together they leave again.
So you can say: Yes, dolphins do swim somewhere else once in a while.
Do dolphins snore?
I have not been able to find any concrete statements on this. Except for Alexander von Humboldt: he mentioned in his notes that he had observed that river dolphins that drew their breath too loud – so to say "snored" - were pushed by the other dolphins in the group to wake them up.
Do dolphins have a thick skin?
The outer skin layer (epidermis) is approximately 20 cm thick and allows water to roll off. It is not only a protection for the internal organs, it is also used for locomotion. Its texture allows it to glide quickly through the water. The skin itself is full of nerve cells. They react to pressure or inform the dolphin about its environment, e.g. the water temperature. The skin also contains colour pigments; melanin grains cause the dark skin colour. The skin colour also gives the dolphins and whales their names, e.g. grey whale.
The researchers discovered a gel-like substance on the skin. This gel - so the scientists write - protects and cleans the dolphins' skin. Over time, microorganisms settle on the skin. So, the researchers assume that dolphins not only jump for the joy of life, they also jump to clean themselves. With each jump, some of the gel on the skin is washed off, thus removing the microorganisms.
Large whales have a thicker skin: up to 50 cm, especially those living in colder areas such as the Arctic. The fat layer under the skin is also called blubber. This blubber coat serves as heat insulation and energy reserve. On the migrations between cold and warmer areas, the skin also regulates the body temperature.
Can I touch dolphins?
Here in the Strait of Gibraltar swimming with dolphins is not allowed. But all over the world these possibilities are offered. What is an unforgettable experience for humans is a nightmare for the dolphins and also endangers their health. It is stress for the animals. The constant touching of the dolphins affects the texture of their skin, it can lead to injuries which are then penetrated by parasites and the wounds become inflamed and hurt. In New Zealand researchers have observed that dolphins change their natural behaviour when people with boats and snorkels are constantly around them. Their eating and resting behaviour changes, and the animals are disturbed in their natural rhythm of life. The scientists found a 75% higher mortality rate in calves. The population living in the Bay of Island shrank by a third. New Zealand has pulled the ripcord and swimming with dolphins is now prohibited. Watching dolphins is now strictly regulated: only a few boats at fixed times.