Southern minke whale
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Southern minke whale ( Balaenoptera bonaerensis ) |
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| Balaenoptera bonaerensis | ||||||||||||
| Burmeister , 1867 |
The southern minke whale ( Balaenoptera bonaerensis ) is a species of furrow whale that lives in the great oceans of the Earth's southern hemisphere between 20 ° and 65 ° S.
features
The southern minke whale is 7.2 to 10.7 meters long and weighs 5.8 to 9.1 t, making it stronger and larger than the northern minke whale. Females can grow up to a meter longer than males. The body is slender and streamlined, the fin on the rear third of the body is relatively high, sickle-shaped and only briefly visible on the surface of the water when swimming. The muzzle is pointed, the upper jaw triangular when viewed from above and has a sharp rostrum ridge in the middle .
The back is dark gray-brown, almost black, the sides blue-gray, the belly lighter. The transition between the dark back and the sides of the body is wavy and blurred. Behind the head, above the flippers, there may be some bright corners, but these can only be seen in nature when visibility is good. The flippers, which are dark on top, have white front edges.
The beards of the front right jaw are white, the other beards are dark. In contrast to those of other baleen whales, the whales of the southern minke whale are asymmetrically colored.
distribution
The southern minke whale lives in the southern hemisphere, especially between 20 ° and 65 ° S. The largest populations are found in the South Atlantic and the southern Indian Ocean , the species is less common in the South Pacific. The animals migrate between regions close to the equator, where they mainly live in shallow coastal waters, and the Antarctic. Probably the sexes separate at times. Reproduction takes place in winter between 10 ° and 30 ° S. In the summer, the whales migrate to the Antarctic feeding grounds. While some individuals only move up to 42 ° S, others migrate to the Ross Sea (72 ° S).
Way of life
The southern minke whale lives individually or in loose groups, which can sometimes comprise hundreds of animals. It feeds on pelagic crustaceans and small schooling fish, especially krill in the Antarctic . The long mating season of the southern minke whales is in the southern winter and extends from June to December (core period August to September). The whale calf is born after a gestation period of about 14 months with a length of 2.4 to 2.8 meters from late May to August, especially in warmer waters.
Surface behavior
When the southern minke whales emerge, the head appears at a low angle first, then the blower . The fin is only visible after the bubble has disappeared. The descent happens with a high rolling motion. Before diving deep, the southern minke whale stands almost vertically and shows tail and fin, but no fluking. He can dive for at least 15 minutes. The bubble rises vertically, is columnar, medium high (2–3 meters) and faint but clearly visible. A whale blows about 5 to 8 times at less than a minute intervals. The southern minke whale is curious about small boats.
Organic duck
The southern minke whale is responsible for the bio-duck noise , which occurs mainly in the southern winter. This sound was first discovered in the 1960s with the help of an Oberon-class sonar and called bio-duck because it resembled a duck cackling. The source of the noise remained unknown until 2014.
Systematics
The southern minke whale was described by the German scientist Hermann Burmeister as early as 1867 . In most publications before 1990, however, one assumed a single, globally living minke whale species ( Balaenoptera acutorostrata ) and the southern population was regarded as conspecific with the northern one. Since 2000, the Scientific Committee of the International Whaling Commission (IWC) has registered the southern minke whale as an independent species that is separate from the northern minke whale ( Balaenoptera acutorostrata ) and its even smaller dwarf population living in the southern hemisphere. Both minke whale species probably form the sister group to the other Balaenoptera species.
Danger
The total population of the southern minke whale is in the hundreds of thousands. The IUCN does not have sufficient data (data deficient) to assess a hazard. For 1978 to 1984 a population of 645,000 to 843,000, for 1985 to 1991 between 786,000 and 869,000 animals is assumed. After a population collapse of around 60%, the number of animals is estimated at 338,000 to 339,000 for the period from 1991 to 2004.
literature
- Hadoram Shirihai & Brett Jarett: Marine Mammals. Franckh-Kosmos Verlags GmbH, 2008, ISBN 978-3-440-11277-9
Individual evidence
- ^ David Matthews, Rod Macleod, Robert D. McCauley: Bio-Duck Activity in the Perth Canyon. An automatic detection algorithm. (pdf) November 5, 1004, p. 1 , accessed on May 31, 2014 (English).
- ↑ Denise Risch, Nicholas J. Gales, Jason Gedamke, Lars Kindermann, Douglas P. Nowacek, Andrew J. Read, Ursula Siebert, Ilse C. Van Opzeeland, Sofie M. Van Parijs, Ari S. Friedlaender: Mysterious bio-duck sound attributed to the Antarctic minke whale (Balaenoptera bonaerensis). Retrieved May 31, 2014 .
- ↑ Jennifer A. Jackson: Phylogenetics of Baleen Whales. doi : 10.1002 / 9780470015902.a0022870
- ↑ IUCN data sheet: PDF
Web links
- Balaenoptera bonaerensis in the Red List of Threatened Species of the IUCN 2008. Posted by: Reilly, SB, Bannister, JL, Best, PB, Brown, M. Brownell Jr., RL, Butterworth, DS, Clapham, PJ, Cooke, J. , Donovan, GP, Urbán, J. & Zerbini, AN, 2008. Retrieved April 17, 2012.