Baleen whales
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Sei whales ( Balaenoptera borealis ) |
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| Mysticeti | ||||||||||||
| Flower , 1864 | ||||||||||||
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The baleen whales (Mysticeti) form one of the two suborders of the whales (Cetacea). They are common in all seas. They are named after the beards , horn plates in the upper jaw instead of teeth, with the help of which krill and other food are filtered out of the water . This group of marine mammals without exception includes the largest known animals in the history of the earth.
anatomy
Most of the colossi among whales are baleen whales. While the toothed whales have only one large whale in their ranks, the sperm whale , the baleen whales include all other large whales, including the blue whale , the largest living animal on earth. All baleen whales grow taller than 6 meters.
The three-sided horn plates in the upper jaw, the so-called beards, are characteristic of the group . There are up to 400 beards on both sides, which are very densely fibrillated. Baleen whales only have teeth as embryos . However, fossil baleen whales with teeth instead of beards are known. In contrast to toothed whales, baleen whales have two blow holes, which often create a V-shaped blow hole.
nutrition
In contrast to the toothed whales, baleen whales feed mainly on animal plankton or smaller marine animals such as krill . But some species also eat fish. To do this, the whale absorbs a large amount of water, which in the furrowed whales is made easier by an extremely elastic throat pouch . Then he closes his jaw and uses his tongue to push the water outwards through the beard. The small animals contained in the water are held back by the beards as if by a filter and can thus be swallowed by the whale without any problems.
Other ways to use the whale are swimming with an open mouth (such as right whales ) or filtering the seabed ( gray whale ).
behavior
hikes
Baleen whales are found in all oceans . All species undertake seasonal migrations. In the summer they stay in the cool waters of the high latitudes to feed, and in the fall they migrate to warmer waters, where they mate and give birth to the young. Outside of the food sources, baleen whales eat little or fast for months. The gray whale even goes on the longest migration of any mammal.
Jumps
Despite their considerable weight, baleen whales are able to jump completely out of the water. The humpback whales are known for their acrobatic behavior , but also other baleen whales break through the water surface with their bodies or beat loudly on it with their fins. The purpose of these statements is not clear.
Sounds
In contrast to toothed whales , baleen whales have not been shown to be able to echo . On the other hand, they are able to emit sounds in the infrasound range at high volume. The calls of the largest whales can be heard over several 100 kilometers. The songs of the humpback whales are unique , the complex sequences of which are modified by stanzas over the years and are probably used for courtship .
Fossil baleen whales
The species Eobalaenoptera harrisoni is extinct . The complete skeleton of a fossil baleen whale from the tertiary era is in the Museum for Nature and Environment Lübeck . The Janjucetidae represent an intermediate form of the two suborders.
Systematics
The baleen whales are usually divided into four, sometimes three families:
- Right whales (Balaenidae) have no throat furrows, a huge head and are up to 16 m long.
- Cetotheriidae , extinct except for one species, the pygmy right whale ( Caperea marginata ).
- Gray whales (Eschrichtiidae) mediate between right and furrow whales; they also consist of only one species.
- Furrow whales (Balaenopteridae) are named after their furrowed throat and chest; In relation to the body they have a smaller head than the right whale, shorter whales and always a dorsal fin (which is missing in some representatives of the aforementioned families). The largest whales belong to this family.
Web links
supporting documents
- ^ Richard Sale: A Complete Guide to Arctic Wildlife . Christopher Helm Publishing House, London 2006, ISBN 0-7136-7039-8 , p. 443.
- ^ R. Ewan Fordyce, Felix G. Marx: The pygmy right whale Caperea marginata: the last of the cetotheres . In: Proceedings of the Royal Society B: Biological Sciences. 280, 2012, p. 20122645, doi : 10.1098 / rspb.2012.2645 .