The black lines underneath the eyes of a cheetah serve the same function as the eye black worn by a football player. The dark color aborbs light, preventing the sun from reflecting up into the eyes. This improves long distance vision in sunny environments that lack shade (such as a savannah, or a football field).
In addition to having a pseudo-penis, the labia of a female hyena are fused and the vaginal canal is only accessable through the clitoris. Mating is thus a difficult activity that requires plenty of practice. It also follows that birth is incredibly difficult and dangerous. Keep in mind that, relative to the mass of the mother, hyena newborns are the largest carnivorans cubs. During labor, the fetus fills and stretches the clitoris until it is pushed out of the tiny opening, ripping the clitoral meatus.
60% of first-time births within captive colonies result in stillborns due to the length of labor involved in the stretching process, and the number is likely even higher in the wild.
Hyenas have scant few secondary sexual characteristics. In fact, this is a photo of a female hyena. A hyena clitoris is equal in size to a hyena penis, due to the species’ characteristically high androgen levels. Though it has been shown that the penile clitoris begins developing prior to the androgen wave in utero, so the condition of female hyenas’ genitals is likely due to multiple evolutionary factors.
Commonly stereotyped as the lowly cretins of the African plains, spotted (“laughing”) hyenas are surprisingly intelligent.
From wikipedia: “Like primates, spotted hyenas use multiple sensory modalities, recognise individual conspecifics, are conscious that some clan-mates may be more reliable than others, recognise 3rd party kin and rank relationships among clan-mates, and adaptively use this knowledge during social decision making. Also, like cercopithecine primates, dominance ranks in hyena societies are not correlated with size or aggression, but with ally networks.”
A pregnant lioness.
Lions are capable of going into multiple estrus cycles, and thus can reproduce outside of any set season. However, lionesses within a pride will often intentionally synchronize their mating cycles so as to birthe their cubs close together. Food competition in a pride is fierce, and smaller cubs stand little chance against another litter of older half-brothers and -sisters. By keeping their gestations close together the lionesses can further ensure the collective success of their offspring.
These days, much of the scientific community considers bears to be not only true hibernators, but super hibernators!
Unlike other, smaller mammals who must wake often to eat and pass waste, and to keep their temperature from falling too low, grizzly bears are able to hibernate without waking for an entire season if need be.
During hibernation a bear is able to live entirely off its fat, despite an average hibernating BMR of 8000 kcal a day. The bear is able to break down the urea that accumulates as a byproduct of fat metabolism, and the resulting nitrogen is used to build protein. This allows a bear to maintain organ and muscle mass under circumstances that would normally lead to severe muscle atrophy. Overall, a bear will lose 15-30% of its weight during hibernation.
Ursus arctos horribilis, better known as the grizzly bear, is distinguished by its humped shoulders, long claws and concave facial profile with heavy brow (think Winnie the Pooh).
Bears did not used to be considered true hibernators, because other deep hibernating mammals typically go through a drastic decrease in body temperature, whereas a bear’s core temperature remains above 88ºF during hibernation (normal for a bear being ~100ºF). Whereas smaller mammals may experience core drops to as low as 40ºF. This enables the bear to more quickly awaken and react to threat. Easy to see why stumbling into a bear cave even in the dead of winter can have a dangerous outcome.
A notable difference between carnivores and herbivores is jaw structure. There are many more differences, but that’s a topic for another post.
The top image is of a rabbit skull. An herbivore’s jaws create a far more pronounced square, such that the animal can lift it’s jaw up and down. This causes all the teeth (or at least the grinding teeth) to come in contact at once, like a nut-cracker.
The bottom image is of a wolf skull (technically it is a fossil replica of a dire wolf skull). A carnivore’s jaws are angled in such a way as to create a shape similar to a pair of scissors. When a wolf—or even a house cat—closes its jaws, the molars will meet first, creating a slicing action to cut and tear flesh.
As omnivores, we humans have a jaw angle somewhere in between the two.
This is a great gray owl, looking very intimidating in an adorable sort of way.
Owls have developed a wing structure that allows them to be—for all practical purposes—completely silent in flight. Noise generated in flight is produced by the vortices formed as air flows over a wing, and is proportional to the size of the vortices. Owl wings have tiny projections along their leading edges, which generate a large number of small vortices, keeping noise to a minimum. Furthermore, the fringe at the wings’ trailing edges (which, by the way, have a smaller number of hooklets at the end of the feather barbs than most birds) help break up waves that are propagated as air flows over and down. The soft down covering much of the rest of the owl further helps to absorb any sound above 2000 hertz, making them almost completely silent.
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