1. Morphological differences in skulls and feeding apparatuses between Antarctic (Balaenoptera bonaerensis) and common (Balaenoptera acutorostrata) minke whales, and the implication for their feeding ecology
- Author
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Nishimura, F., Kim, Y., Bando, T., Fujise, Y., Nakamura, G., Murase, H., and Kato, H.
- Subjects
Morphological variation -- Research ,Balaenoptera acutorostrata -- Physiological aspects -- Food and nutrition -- Environmental aspects ,Zoological research ,Skull -- Physiological aspects ,Zoology and wildlife conservation - Abstract
The differences in rorqual feeding ecology have been linked to the presence of different morphological markers. The Antarctic minke whale (Balaenoptera bonaerensis Burmeister, 1867) and the common minke whale (Balaenoptera acutorostrata Lacepede, 1804) are closely related species, but their morphological differences have not been fully investigated. In this study, we compared 21 skull and 11 feeding apparatus (baleen and mouth-related parts) measurement points between these two species using hundreds of individuals covering a wide range of body lengths in both sexes. Their engulfment capacities were estimated using these measurements. Our results show that Antarctic minke whales have (i) proportionally larger skulls to the body length, (ii) more dorsoventrally and laterally curved rostra, (iii) proportionally larger feeding apparatuses to the condylobasal length, and (iv) significantly larger engulfment capacity than common minke whales. These differences could indicate that Antarctic minke whales have developed a feeding strategy suitable for feeding on krill, which forms large schools. In contrast, common minke whales have adapted to prey on small pelagic fishes that are agile and form small schools. Key words: Balaenoptera bonaerensis, Balaenoptera acutorostrata, Antarctic minke whale, common minke whale, skull morphology, feeding morphology, engulfment capacity. Les differences sur le plan de l'ecologie de l'alimentation chez les rorquals ont ete associees a la presence de differents marqueurs morphologiques. Bien que le rorqual antarctique (Balaenoptera bonaerensis Burmeister, 1867) et le petit rorqual (Balaenoptera acutorostrata Lacepede, 1804) soient des especes etroitement reliees, leurs differences morphologiques n'ont pas ete examinees de maniere exhaustive. Nous avons compare 21 et 11 mesures du crane et de l'appareil d'alimentation (fanons et parties buccales), respectivement, obtenues de centaines de specimens des deux especes couvrant une grande fourchette de longueurs du corps pour les deux sexes. La capacite d'engouffrement a ete estimee a la lumiere de ces mesures. Nos resultats montrent que les rorquals antarctiques ont (i) des cranes proportionnellement plus grands par rapport a la longueur du corps, (ii) des rostres a plus forte courbure dorsoventrale et laterale, (iii) des appareils d'alimentation proportionnellement plus grands par rapport a la longueur condylobasale et (iv) une capacite d'engouffrement significativement plus grande que les petits rorquals. Ces differences pourraient indiquer que les rorquals antarctiques ont developpe une strategie d'alimentation adaptee a la consommation de krill, qui forme de grands bancs, alors que les petits rorquals se sont adaptes a la consommation de petits poissons pelagiques agiles formant de petits bancs. [Traduit par la Redaction] Mots-cles : Balaenoptera bonaerensis, Balaenoptera acutorostrata, rorqual antarctique, petit rorqual, morphologie cranienne, morphologie de l'appareil alimentaire, capacite d'engouffrement., Introduction Feeding is one of the most fundamental aspects for any animal species, as it is directly tied to their survival. Each cetacean species has its own feeding ecology (i.e., [...]
- Published
- 2021
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