Toothed whales
| Toothed whales | ||||||||||||
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Black dolphin ( Lagenorhynchus obscurus ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Odontoceti | ||||||||||||
| Flower , 1867 |
The toothed whales (Odontoceti) are one of the two suborders of the whales (Cetacea). They are mainly characterized by the eponymous presence of teeth, the shape and number of which, however, vary greatly within the group. In addition, unlike the baleen whales (Mysticeti), they only have one, not two, blowholes. Toothed whales are carnivorous and feed primarily on fish , octopus, and in some cases other marine mammals.
The best-known and at the same time most species-rich family of toothed whales are the dolphins .
anatomy
Almost all toothed whales are much smaller than the baleen whales. Only the sperm whale is counted among the large whales . The remaining species are small to medium in size. Furthermore, toothed whales differ from baleen whales in that they only have a single blowhole.
The teeth are very different in the different species. Many toothed whales have many teeth, up to 100 in some dolphins . The narwhal , on the other hand, has a long tusk and the males of the almost toothless beaked whales have bizarre teeth. It is relatively easy to tell the age of toothed whales. Every year a new layer forms on your teeth - it actually corresponds roughly to the annual rings of a tree. The oldest toothed whale found so far was a 70-ring sperm whale. Bottlenose dolphins are assumed to have a peak age of 40 years.
behavior
Locomotion
Most toothed whales are fast swimmers. The small species occasionally ride waves, such as the bow waves of ships. Dolphins like the spinner , who are also known for their acrobatic jumps, are particularly common .
Sounds
Sounds play an important role in toothed whales. In addition to numerous whistling sounds for communication, they also master the use of ultrasound tones for echolocation . This sense is particularly important when hunting.
Social behavior
Toothed whales usually live in groups of a few to about a dozen animals. These so-called schools can temporarily unite to form larger groups of up to thousands of whales. Toothed whales are capable of complex services, such as cooperation in hunting schools of fish. In captivity, some species have a high ability to learn, which is why zoologists consider them to be among the most intelligent animals.
Taxonomy
It divides the recent toothed whales today in ten families:
- Sperm whales (Physeteridae)
- Pygmy Sperm whales (Kogiidae)
- Beaked whales (Ziphiidae)
- Ganges dolphins (Platanistidae)
- Amazon River Dolphins (Iniidae)
- † Chinese river dolphin (Lipotidae)
- La Plata Dolphin (Pontoporiidae)
- Pilot whales (Monodontidae)
- Porpoises (Phocoenidae)
- Dolphins (Delphinidae)
There are several approaches to grouping these families into superfamilies. The only thing that is certain is that the families of dolphins, porpoises and greyhound whales are related to one another. They are sometimes grouped together as dolphin-like (Delphinoidea). In contrast, the system of river dolphins is controversial. Sometimes they were grouped together in one family, sometimes they were divided into four families as merely convergent animals. According to molecular genetic studies, the special position of the Ganges dolphins and the relationship of the other three genera ( Inia , Pontoporia and Lipotes ) is likely.
Sperm whales and minke sperm whales are probably original families of the toothed whales and are sister groups to the other families .
Human influence
The sperm whale has long been the industry intensively hunted , mainly due to the previously used for perfumery Ambra . While some small whales such as the pilot whale are still hunted today, most species are mainly threatened by bycatch . Thousands of dolphins drown in the nets, especially when fishing for tuna .
The keeping of small whales, mostly bottlenose dolphins , killer whales and belugas , is a major attraction for oceanariums and zoos. However, it is controversial because of the large space required by marine mammals. The same applies to its use in dolphin therapy .
literature
- DE Wilson and DM Reeder: Mammal Species of the World. Johns Hopkins University Press 2005, ISBN 0-8018-8221-4 .
Web links
Individual evidence
- ↑ Don E. Wilson, Russell A. Mittermeier: Handbook of the Mammals of the World - Volume 4, Sea Mammals. Lynx Edicions, July 2014, ISBN 978-84-96553-93-4 .