生理学: 海猟

生理学海猟

海猟：どんな生き物？

Sea otters, unlike seals and whales, do not have subcutaneous fat and rely on fur for heat retention. Their hair density reaches 45,000 per cm², creating an air layer.
A female sea otter's pregnancy begins with a delay and includes a latent phase lasting 2–3 months. The embryo does not attach to the uterine wall during this time, a development method shared by about 100 mammal species.
Sea otters have a unique among mammals adaptation of vision for an amphibious lifestyle. Their eyes allow them to focus on both underwater and above-water objects, and they have emmetropic vision both in water and in air.
Sea otters have unique morphological features that distinguish them from other species. Because of this, their classification has been repeatedly revised.
Modern sea otters have fewer alleles in their genes than their ancestors 300 years ago, when the same genes had dozens of alleles.
Sea otters have a metabolism rate 8 times higher than that of terrestrial mammals of similar size. Sea otters need to eat food amounting to 20–25% of their body weight every day.
The sea otter's dental structure is unlike that of mustelids and most carnivorous mammals. It has only two pairs of lower incisors (dental formula: 3.1.3/3.1.3).
The sea otter's lungs account for 6 % of body mass and fit into the thoracic cavity due to an oblique diaphragm. Sea otters have lungs 2–4 times larger than those of pinnipeds.
The sea otter uses stones as tools when foraging, selecting them by shape and size.
The sea otter’s nostrils close when diving underwater to prevent water from entering the nose. The elastic walls of the nostrils allow this to happen.
The sea otter's digestive tract makes up 15.5% of its body weight. Its intestine is long and exceeds the body length more than 10 times.
The sea otter's molars are broad and flattened, adapted for chewing hard mollusks and crab shells, not for holding slippery fish. In some individuals, the number of teeth reaches 34.
The sea otter's nasal cavities are greatly enlarged and have a complex structure, related to breathing characteristics during diving. Many internal organs of the sea otter are enlarged compared to other mammals in proportion to body weight.
The ear flap of a sea otter closes with elastic walls when submerged, preventing water from entering the ear. The elastic walls close the flap, narrowing it toward the outside and forming a tube.
Sea otters eat birds and meat from dead animals, especially foxes. During times of scarcity, they may hunt shorebirds.

生理学 海猟

生理学海猟