Rabbits have hinged skulls and three eyelids

Originally posted here: https://mcgill.ca/oss/article/did-you-know/rabbits-have-hinged-skulls-and-three-eyelids

Rabbits and hares are pretty cute, but they’re also fascinating. 

Rabbits’ physiology is perfectly adapted for their needs. Being prey animals, rabbits need to be very aware of their surroundings. Their large ears and good hearing are well known, but did you know they also have vision that encompasses almost 360 degrees? Their eyes are situated high on the sides of their faces, giving them only a tiny blind spot directly in front of them. They even sleep with their eyes open, blinking only their nictitating membranes, or clear third eyelids, to keep their eyes moist.

Even if they can’t see or hear a predator, rabbits can probably smell them. They are obligate nasal breathers, meaning they breathe only through their noses. This way, they can always smell their environment, even when eating.

When they do smell, see or hear a predator, rabbits have to be able to make quick escapes. To help with this bunnies have very large back feet, and hinged skulls to absorb shock. Their cranial hinge allows rabbits to run at speeds above which the impact of their feet would rattle their brain around.

Remember, rabbits might be impressive, but they’re impressively bad Easter presents. Bunnies are the most abandoned pet in North America, and that’s not a statistic you want to contribute to.

Rabbits Eat Their Own Poop

Originally posted here: https://mcgill.ca/oss/article/did-you-know/rabbits-eat-their-own-poop

Rabbits are foraging herbivores, eating mostly grass and weeds. But this fibrous, cellulose rich diet isn’t the easiest to digest, and by the time their dinner has make it through their intestines it still contains many of the nutrients the bunnies need. 

Rabbits and hares beat this problem with a special kind of digestion called hindgut fermentation. In short, they eat their own poop and digest it a second time. Bunnies actually make two different kinds of droppings: little black round ones and softer black ones known as cecotropes that are eaten. This process is known as coprophagy, and functions the same as cows chewing their cud.

It’s very important for a rabbit’s digestive system to keep moving fluidly, as they need to re-ingest their cecotropes in order to get the nutrients they need. If anything gets stuck in a bunny’s esophagus or intestines, they’re out of luck, since they’re incapable of vomiting.

From tiny bodies to giant ears, rabbits have super specialized physiologies

Originally posted here: https://mcgill.ca/oss/article/did-you-know/tinies-bodies-giant-ears-rabbits-have-super-specialized-physiologies

We’ve already seen that rabbits and hares have quite interesting physiology, but for certain species of leporidae the adaptations get even more extreme.

The smallest rabbit in existence is the pygmy rabbit, who weighs on average only 450 grams! They’re found in the western US,and are one of the only rabbit species who dig their own burrows, as opposed to repurposing the found burrows of other animals.

Hares on the other handdon’t use burrows at all,but make nests in grass and underbrush. Part of the reason for this is their impressive ability to run away from predators, as opposed to hiding from them in the first place. Some species of hares can run as fast at 80 km/h! This speed requires some serious shock absorption to keep their brains from being rattled, so they’ve actually developed hinged skulls.

Rabbits are generally known for their massive ears, but they actually do a lot more than just hear predators and friends. Rabbits ears are crucial for thermoregulation! Their large surface areas allow bunnies to release their heat and keep cool, that’s why bunnies that live in hot areas tend to have the largest ears.

Rabbits, Reproduction and Making Mochi on the Moon

Photo made by Cassandra Lee
Article originally posted here: https://mcgill.ca/oss/article/did-you-know/rabbits-reproduction-and-making-mochi-moon

Rabbits have an undoubtedly important association with Easter, but they’ve played important roles in many societies through the ages. 

In Japanese folklore there is a rabbit who lives on the moon and makes mochi (rice cakes). Historically rabbits were believed to be hermaphrodites, which led to their association with the Virgin Mary in Christianity, as they could reproduce while maintaining their virginity.

In modern times, rabbits continued their association with reproduction when they became the vector for the first pregnancy test. Scientists discovered in 1931 that if the urine of a pregnant female human was injected into an immature female mouse or rabbit, the animal’s ovaries would show signs of follicular maturation and ovulation within a few days, due to the presence of human chorionic gonadotropin (hCG).

This  rabbit test lead to the phrase “the rabbit died” being a euphemism for being pregnant, though this itself is a misnomer, since all rabbits and mice used for this test had to be killed before their ovaries could be examined and the test results given.

Luckily today we detect hCG in pregnant people’s urine via the dipstick test, no bunny death necessary! Though rabbits have maintained their association with sex and fertility, largely due to their short (only 30 days!) gestational periods.