About the wisdom of children (part two)
by firmm Team
Text: Edeltraud Konradt, Photos: firmm
This year I was surprised how many children told me that they have a book about whales and what they read in it, or that they did a project or a presentation about whales and dolphins at school.
I would therefore like to begin with the children's statements, to which nothing needs to be added:
- Dolphins in a dolphinarium: that is cruelty to animals
- Tuna fishing must be prohibited
- Catching dolphins is mean
a 6 year old shouted to me in the lecture when I showed the picture of the Orca. Killer what does that actually mean? According to Wikipedia, "Assassin. This is not true for the Orca in many ways. I found 90 synonyms for the word kill. All of them describe human behaviour. The name probably comes from the fact that fishermen in former times observed orcas eating other mammals. That's why they called them “the whale that kills”, which was then turned around into Killer Whales.
The Orca kills to feed. It sometimes uses rude hunting techniques to get its prey. He kills for the urgent hunger and mostly only as much as the family will eat immediately. The Orcas live together in small families (called schools). The group is led by the oldest female, who passes on her acquired knowledge to her offspring. An Orca female needs 20 years to learn social structures, family communication and hunting techniques.
How much water do whales drink per day?
Most whales live in the open sea, which consists of salt water of varying concentrations (3.5%, 535 mmol/litre). Whales as mammals are related to us and must also have a so-called isotonic salt content (about 0.9%) inside their bodies, which is far below the salt content of the sea water. One could assume that there are hidden freshwater springs under water to which the whales swim to drink. Such springs exist, but they are far too rare. This is why evolution has found another freshwater source for dolphins that live in the open sea.
Whales and dolphins have only a low body water balance due to their huge fat layer (blubber), which has to be kept in balance. Humans have about 60% body water while bottlenose dolphins have only about 37% body water.
The water contained in prey animals can serve as drinking water. Fat and protein can also be metabolized to water to a certain extent. However, the high protein richness of fish through appropriate urea production requires excretion via the urine, where water loss occurs again.
In contrast to other marine mammals, whales are also known to consume certain amounts of salt water. A special physiological achievement of the animals, because their kidneys are able to produce a more concentrated urine.
GASKIN (1986) has described that the skin plays a decisive role. The skin functions as a semi-permeable membrane through which water can enter the animal, but no salt is let through.
There is unfortunately no exact information about the water balance of all whales, because there are some differences between the individual species. The combination of water from food with occasional salt water intake is the first choice. The special performance of the skin in relation to the fluid balance of the whales requires further investigations. (Source: cetacea.de)
What kind of whales live in the Pacific?
The 5 oceans of the earth are: Arctic Ocean, Atlantic Ocean, Indian Ocean, Pacific Ocean, and Southern Ocean. The Pacific Ocean is the largest and deepest ocean on Earth and borders all other oceans.
Gray Whales live only in the Pacific. They are baleen whales and the only representatives of this monotypical genus. A distinction is made between a West Pacific and an East Pacific population. The once in the Atlantic living Gray Whales died out at the latest in the 17th century. The Atlantic Gray Whales lived off Spitsbergen and Canada as well as probably off North-Africa in the winter.
Gray Whales reach a length of 13 to 15 meters and a weight of 25 to 34 tons. Gray Whales feed only in the summer months. The accumulated fat-reserves must suffice for the long migrations to the reproduction grounds in the winter. Gray Whales feed on amphipods, other small crabs and fish. As only whale, the Gray Whale descends also to the sea ground on their search for food. Therefore, it whirls up the deposits on the seabed. They lie down on their side and slowly swimming suck in the bottom sediment. With the help of the baleens, the food-relevant marine animals are then filtered out of the mud. Mostly they roll on the right side which causes a faster wear of the right baleen.
The gestation period is 11 to 12 months; the calves are approximately 5 meters long at the birth and weigh half a ton. They are suckled over the winter, during the migration into the summer-areas until the autumn and then weaned.
According to environmentalists, the last 130 West Pacific Gray Whales, 30 of which are fertile females, are threatened by a new oil platform off the Russian island of Sakhalin. (Source: Wikipedia)
Fin Whales have two blowholes: one on the back and one on the head!
No, that's not the way it is. Fin Whales have two blowholes centred on their head, they occur much more frequently than Blue Whales, but their numbers are also endangered. Fin Whales are closely related with Blue Whales. They are able to produce hybrids, although the evolutionary line of both species has been separated for at least five million years. Occasionally, it comes to cross-breeds between the types. Life expectancy is one hundred years. (Source: Wikipedia)
How long can dolphins, stranded on land, survive?
Whale strandings have different causes; we differentiate between living and dead strandings. Dolphins are very social animals, mass strandings occur when the leading animal is injured or ill, loses its sense of orientation and the other animals follow. A disturbance of the sonar system of the animals by underwater noise can also be a cause. In New Zealand it happens again and again that single whales get ashore.
So it depends on the general condition of the dolphin. Where was he washed ashore? In the Arctic, in the Indian Ocean? At which time of year, in which condition? Injured, nearly starved to death, etc. There is no single cause or reason. Stranded dolphins die from the conditions that led to the stranding.
Are Sperm Whales eaten too?
No, Sperm Whales have only one enemy: humans. Due to hunting in the past, the populations of Sperm Whales are so small that they are considered endangered.
Their spermaceti (from which high-quality lubricant for fine mechanics was made) and the fat (also blubber) which was used as oil for lamps and industry were in demand. Today, Sperm Whales die from plastic waste that swims in the sea and smells like food over time, which is why they confuse it with it.
Pink dolphins don't exist!
They exist. Pink dolphins are sometimes albinos, but river dolphins also take on a pink colour when their skin is well supplied with blood in adulthood.
Three species of river dolphins live in the Amazon region: Boto (Inia geoffrensis) in the Amazon River, the Bolivian river dolphin (Inia boliviensis) in the upper reaches of the Rio Madeira and the Araguaian river dolphin (Inia araguaiaensis) in the Araguaia-Tocantins basins of Brazil. The Indo-Pacific Hump-backed Dolphin off Hong Kong (Sousa chinensis), also known as the "pink dolphin", is also threatened. Pink dolphins in the Amazon region are 2 to 3 metres long and weigh between 85 and 160 kilograms. Their colour changes with age. Young animals are silver-grey, older dolphins turn pink. They are solitary, rarely seen with other dolphins.
How do dolphins pee?
Of course, dolphins have excretory organs. The ingested food is digested in the body; undigested food has to come out via urine and faeces. This means they have an anus for excretion of excrement and a urogenital opening for excretion of urine. Both openings are hidden under skin folds so that the body surface remains smooth and thus increases swimming efficiency by reducing drag.
The quantities of excrements are difficult to determine. The only certainty is that whale urine is also yellow. Whale faeces of baleen whales are often orange, while those of toothed whales are more brownish. The excrements are scientifically very interesting, because they fertilize the oceans. They contain nutrients that are used by microorganisms in the sea.
Dolphins are eaten by sharks!
Yes, but not all sharks eat dolphins. Sharks are carnivores. Most species feed on fish, crabs, molluscs and seals. Some sharks also feed on seabirds, dolphins or their own species.