The Respiratory System of the Arctocephalus australis in Comparison to the Dog as a Land-Carnivore: Are There Adaptations to Marine Life?

SIMPLE SUMMARY: It is normally recognized that anatomy is crucial for an improved knowledge of many physiological adaptations. In the case of marine mammals, their ability to dive for long periods of time is especially striking. They spend most of their lives in water, although in general terms, they behave and have characteristics very similar to those of land mammals. Our results demonstrate that, due to its capacity to stay under water, the respiratory apparatus of the South American fur seal shows specific characteristics. Yet, in general terms, being a carnivore seems to be the main characteristic of this species, and the adaptations to the aquatic environment being less important. ABSTRACT: Marine mammals are divided into three groups, with similar adaptations resulting from their aquatic lifestyle: sirenians, pinnipeds, and cetaceans. The present work focused on the South American fur seal, or Arctocephalus australis, a carnivore included in the pinnipeds group. We assessed whether the anatomical features of the Arctocephalus australis’ respiratory system are comparable to those of other land-carnivores or whether these individuals show anatomical adaptations related to their ability to dive or their breath-holding capacities. We studied 11 cadavers of Arctocephalus australis, which included adult (n = 2) and juvenile (n = 9) individuals, by anatomically dissecting their isolated entire respiratory system. Although it is generally similar to that in land-carnivores, we demonstrated that the Arctocephalus australis’s respiratory apparatus shows several specific characteristics. Therefore, our results are of great importance for clinical diagnostic and wildlife conservation purposes.