Furrow whales
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Jumping humpback whale |
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| Gray , 1864 |
The furrow whales (Balaenopteridae; lt. Balaena "whale" derived from the ancient Greek φάλ (λ) αινα "whale") are a family of baleen whales . These include the largest of all whales and thus the largest living animals at all.
features
The eight to nine species, depending on the system, are between 7 and 31 m long. They differ from the right whales , the other large family of baleen whales, in the presence of a dorsal fin, a slimmer shape, significantly shorter and wider whales and the eponymous throat furrows. The furrows are longitudinal folds that run from the throat over the chest to the center of the body; each of the 10-100 furrows is about 5 cm deep; they expand when the whale opens its mouth to take in water, causing the throat area to enlarge considerably. Furrow whales open their mouths up to an angle of 90 °, which is made possible by a special structure of the jaw. The head and jaw take up about a quarter of the total length of the body.
Way of life
Furrow whales are fast swimmers. They go on great hikes, switching between warm and cold climates. Therefore, furrow whales are common in all large oceans, but avoid small tributaries.
By widening the throat area, the whales can absorb more water than their own body weight within a few seconds. When the water is squeezed out, which takes about a minute, about ten kilograms of krill and fish stick to the whales for each process . This can happen several times within a single dive. However, this is very strenuous for the whale, which is why these dives are only relatively short (15-20 minutes).
The furrow whales have always played an important ecological role. In the Antarctic region alone, over 100 million tons of krill were eaten by large whales each year . Due to the absence of the whales, the mass of the krill increased considerably and enabled other animals such as the crab-eaters to explode.
Threat and protection
All furrow whales have been heavily hunted for their trans and meat. Although they were considered less valuable than the right whales because of their thinner layer of fat, after the right whales were largely extinct, furrowed whales were hunted. This brought the large species such as the blue whale, fin whale and humpback whale to the brink of extinction . They have been protected since 1986, but minke whales are still hunted. In spite of the protection regulations, sei whales are also still hunted in Japan and Iceland as part of a controversial research program of the International Whaling Commission (IWC) - although on a much smaller scale.
Systematics
- Genus Megaptera
- Humpback whale ( Megaptera novaeangliae )
- Genus Balaenoptera
- Northern minke whale ( Balaenoptera acutorostrata )
- Southern minke whale ( Balaenoptera bonaerensis )
- Fin whale ( Balaenoptera physalus )
- Blue whale ( Balaenoptera musculus )
- Omura's whale ( Balaenoptera omurai )
- Bryde's whale ( Balaenoptera brydei ; synonym Balaenoptera edeni )
- Sei whale ( Balaenoptera borealis )
The Omura whale, first described in 2003 , was initially considered a smaller Bryde's whale. However, genetic analyzes of tissue samples showed that it is a species of its own. The status of the eden whale, which is also proposed as a separate species , is unclear, currently it is still added to the Bryde's whale.
A genetic study published in 2018, which is based on a comparison of the complete genetic makeup of the blue whale and other furrow whales, found that the humpback whale, which was previously placed in a separate genus, is closely related to the fin whale and that the gray whale, so far the only species of the family Eschrichtiidae, despite its different morphology and way of life, also belongs to the genus Balaenoptera . In addition, the furrowed whale species have mated again and again during their evolution across the emerging species boundaries, as there are no natural barriers in the open ocean. So there was no allopatric speciation .
The relationships between the furrow whales and the right whales as an outer group according to Árnason et al .:
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The pampau whale Praemegaptera pampauensis from the Miocene , discovered in Groß Pampau ( Schleswig-Holstein ) in 1989, is also part of the furrow whale family.
Web links
Individual evidence
- ↑ Goldbogen, Spektrum der Wissenschaft 10/2010
- ↑ Roughly on the part of the WWF , see [1] ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. .
- ↑ a b T.A. Deméré: Family Balaenopteridae (Rorquals); Bryde's Whale Balaenoptera edeni In: Don E. Wilson, Russell A. Mittermeier: Handbook of the Mammals of the World. 4. Sea Mammals. Lynx Edicions, Barcelona 2014; Pp. 289-290. ISBN 978-84-96553-93-4 .
- ↑ a b Úlfur Árnason, Fritjof Lammers, Vikas Kumar, Maria A. Nilsson and Axel Janke. Whole genome sequencing of the blue whale and other rorquals find signatures for introgressive gene flow. Science Advances 04 Apr 2018, Vol. 4, no.4 , DOI: 10.1126 / sciadv.aap9873
- ^ Günther Behrmann: The baleen whale from the Miocene of Gr.-Pampau (Schleswig-Holstein). In: Geschiebekunde aktuell. 11, No. 4, 1995, pp. 119-126, hdl : 10013 / epic.10844.d001 (pdf; 1 MB).
