If this question had been posed more than a couple of decades ago, the obvious answer would have been ‘YES.’ In fact, until the early twentieth century, taxonomists used to place the rabbits and other members of the same order in the order Rodentia, commonly called ‘rodents.’ It was due to the lack of phylogenetic studies back then. When scientists began to classify the animals based on their genetic makeups, evolutionary histories, and phyletic relationships, some confusion arose in the classification of rabbits as rodents.
Until 1912, there had been a substantial debate on whether rabbits should be placed among rodents. If not, which animal family the rabbit belongs to? Of course, the misconception between rodents and rabbits was partially due to the history of classification and lack of research. After 1912, the rabbits, hares, and pikas were separated from the Rodents and were placed in a different order. This classification is still being used by modern taxonomists.
Now, the answer is “NO, rabbits are not rodents.” Although rabbits and rodents have a lot in common on the outside, they are entirely different animals. When you look closely and study the two orders in detail, you’ll discover the clear differences between the two. The rabbits and hares were still classified as rodents in the curriculums because the textbooks took decades to make up ground for the modern taxonomy. Even in popular culture, rabbits took considerably longer to be distinguished from rodents.
Rodentia is actually the largest and the most diverse group of mammals. Therefore, we often confuse many other animals with rodents just because of their superficial similarities. This is the reason that moles, desmans, hedgehogs, and shrews, all belonging to the Eulipotyphla order, are frequently mistaken for rodents as well. In this article, we’ll debunk some common misunderstandings about the classification of rabbits and their relationship with rodents.
What Are Rodents?
Rodents are the animals belonging to the taxonomic order Rodentia. They are the largest group of mammals and are quite small in size. Therefore, they often get preyed on by large animals. For defense, they have sharp teeth and claws. They have more than 2000 living species. Many rodent species are known to have been extinct, such as Castoroids (giant beavers) found in North America, Josephoartigasia found in South America, Giant hutias found in West Indies, and many others more.
It is an extremely diverse order, with all of them having some properties in common, like claws with 2 to 3 digits, single pair of upper and lower incisors, and a great sense of vision and listening. But just like humans, these senses weaken with age in rodents. They lose some of the listening capacity and lose eyesight too. In addition, their muscles degenerate, and the body loses its physical strength.
Which Animals Are Classified as Rodents?
There is a long list of small mammals in this group. Some representatives of the group include:
- Rats are long-tailed rodents that are known to spread diseases in humans through Salmonella and Hantavirus.
- Guinea pigs are great pets. They cuddle a lot and are very affectionate. Guinea pigs are also known as domestic cavies.
- Hamsters alone comprise 19 species, among which the best known is the Syrian hamster.
- Beavers are extremely cute, soft, and small mammals, with their wild species being dangerous to humans.
- Squirrels are often seen climbing the trees. But these small rodents do live on land and fly as well.
- Chinchillas are a mixture of other rodents. Their anterior portion looks like that of a rat with a tail and posterior body similar to that of a squirrel.
Difference Between Rabbits and Rodents
The domesticated rabbits and the wild rabbits have gained human attention due to how adorable and lovely they are. Is it possible that such a famous animal does not represent its group? You didn’t find rabbit on the list of rodents above, right? It is because rabbits are not rodents, to begin with. Both are different in many aspects.
Teeth
Dental anatomy is the major reason for keeping rabbits out of the Rodentia order. The basic difference is the number of incisor teeth. Rabbit incisors are 6 in number. Four incisors are located in the upper jaw, and two are located in the lower jaw. The second pair of upper incisors are small in size and is often located behind the main pair of top incisors hence not visible from the outside. In addition, they lack canine teeth as they are herbivores. Instead, they have peg teeth behind the front teeth and 22 back teeth.
On the other side, rodent incisors are only 4 in number. One pair is in the upper jaw and the other in the lower jaw. They lack canine teeth too and have a set of peg teeth. There are relatively flat teeth at the back of the mouth called premolars and molars, which may vary in number.
Rabbits have harder enamel on the outer surface of both sides of the teeth, whereas rodents don’t. Their teeth are covered with hard enamel from the front but have soft dentin at the back. The purpose of this dentin is to give the teeth a sharp shape. You can easily observe the front teeth of both animals. Rodents have sharp, while rabbits have flat teeth. Furthermore, rodents have orange incisors while rabbits have white.
Rabbit and rodent teeth have space between the incisors and the premolars called diastema. Unlike human teeth, their incisor teeth don’t have roots and grow continuously; it is called indeterminate growth. It is the reason both the rabbits and the rodents need fibrous plant matter to wear their teeth down. If not taken care of, they can face many dental problems.
Digestive Systems
Though the major parts of their digestive systems are similar, they differ a bit in their functions. Rabbits have a blind pouch called the caecum at the anterior portion of the large intestine. Rabbit’s caecum is a habitat of numerous beneficial bacteria that aid the breakdown of plant matter, especially cellulose, keeping the rabbit’s digestive tract in a good shape and thus keeping the rabbit healthy.
Rodents have caecum, but its function is mostly to store plant material and absorb minerals and salts from the digested plant matter. Moreover, both the rabbits and the rodents have different bacteria in their guts. For example, an adult rabbit has Bactericides, while a young rabbit has Enterobacteria and Streptococci. On the other hand, rodents have a great diversity of microflora in their digestive system.
Type of Nutrition
Both the wild and the pet rabbits are obligate herbivores. They cannot eat meat as they cannot digest high protein foods. Even the pet food available for bunnies is low in protein supplements. On the other hand, a few rodents are omnivores. They eat insects, worms, and eggs. Among the list are hamsters, rats, mice, and squirrels. But not a single rodent has been found to be an obligate carnivore yet.
Others like chinchillas and guinea pigs are herbivores and eat leaves, flowers, seeds, roots, and bark of trees. Their diet is completely different from that of rabbits that comprises more fibrous hay and pellets.
Reproductive Systems
Rodents like rats are much faster breeders as compared to rabbits. A mouse is sexually mature and can start breeding as early as four weeks after its birth. On the other hand, it takes at least six months of age for a rabbit to mature sexually and start mating with other rabbits. The average gestation period for rabbits is 31 days, though it may differ from one breed to another and usually lies somewhere between 30 days to 33 days. On the other hand, rats have shorter gestation periods of 21 to 23 days. Therefore, the phrase “breeding like rabbits” is actually more appropriate for rats.
Another important difference in the reproductive systems of rodents and a rabbit is the presence of baculum or penis bone. The baculum is actually a bone structure found in most mammals and helps harden the male’s penis during mating. It allows the animal to mate for extended periods of time. Hydraulics for animals lacking baculum bones is significantly slower as compared to inserting a bony penis into the female genitalia and attaining a speedy erection. These bones are not found in humans, horses, kangaroos, dolphins, and whales.
Rabbits and hares also lack the penis bone present in rodents such as rats. The evolution of the baculum in rodents has allowed for faster and longer matings. It causes a rapid erection in the male penis instead of the erection without bone, which is generally slow being under hormonal control. An important benefit of rapid erections in rodents is that predators are less likely to attack during mating. Thanks to this bony structure, these animals have to spend less time in vulnerable and prominent mating positions.
Tail
Rodents usually have long tails as compared to rabbits. A common pet rabbit called a European rabbit has a tail of length 4 to 8 centimeters only. On the other hand, an adult rat can have a tail of length 7 to 9 inches (18 to 23 centimeters). In addition to it, mice have thin hair, and rats have no hair on their tail at all. Their tail is scaly. While rabbits have furry tails, they feel so soft to touch and often look like a plush ball from a distance.
Ears
The opposite of the tail goes for the ears. Rabbits have long ears as they serve two purposes. First, they equip them with an excellent hearing sense as they are prey animals and hear the footsteps of the predator from a distance and escape. Secondly, they help in regulating body temperature. In cold weather, the blood vessels in the ear constrict (called vasoconstriction) to minimize heat loss. When the temperature rises, the vessels dilate (called vasodilation) to maximize the heat loss.
Rodents have comparatively smaller ears. Rat has a bit pointy yet smaller ears while mouse has round but a bit longer ears. Still, the mouse cannot compete with the length of the rabbit ears.
Why Do People Confuse Rabbits With Rodents?
Despite the uncountable differences from the body structure to these mammals’ internal anatomy, they are still confused by many people. It’s obvious that there are some similarities among both mammals. Some similarities are listed below:
Gestation Period
The gestation period of most mammals is quite long, ranging from 100 to over 300 days. But these two families of rabbits and rodents have shorter gestation periods. Rabbits deliver their babies after being pregnant for 30 to 33 days, whereas different breeds of rodents like mice and rats deliver their babies on the twenty-first or the twenty-third day.
Both are induced ovulators. It means the females can get pregnant each time after mating with the males. So they can be pregnant 12 times per year, and both of them deliver babies in a litter. Each litter can have 1 to 14 babies in it.
Some rodents might have a longer gestation period, like a guinea pig that remains pregnant for 60 days. But most rodents have no longer pregnancy period than 30 days.
Placental Mammals
There are three types of mammals. The first category involves the monotremes. These animals lay eggs that have soft shells. The baby develops inside the egg and comes out at maturation. Examples of such animals are platypus and echidnas. The second class is of marsupials. They include kangaroos, koalas, and other related animals. These animals have a small pouch on their lower abdomen. They give premature birth to their babies and then keep them inside these pouches. Inside the pouches are the nipples from which they get nourishment and grow.
The third class is of placentals. Both the rabbits and the rodents belong to this category. These animals nourish their babies inside their womb through a connection called the placenta; the name placental mammals are also derived from it. The placenta is a vascular organ that allows the exchange of blood and nutrients between the mother and the baby. After the development is completed, a female rabbit or a female rodent gives birth to their young ones.
Coprophagous
Coprophagy is another similarity between the rabbits and the rodents, which often leads to confusion between them. Coprophagy is a process in which an animal eats its own feces. Although this behavior is found in different animals, there may be different reasons for an animal showing coprophagy. For example, an animal may eat its own feces out of boredom, due to an illness, or in order to clean its place. Coprophagy is shown by foals, dogs, and nonhuman primates to a lesser extent.
Both rabbits and rodents are coprophagous. They don’t do this due to some temporary reasons; it is actually a part of their normal digestive routine. Both rodents and rabbits are hindgut fermenters. It means that in these animals, nutrient production by the microflora of the gut takes place in the lower gastrointestinal system. Because the lower digestive system is involved in fermentation, very little absorption of nutrients occurs here. Therefore, coprophagy is required in rodents and rabbits for the supply of several vital nutrients, which are wasted in the form of fecal matter. It is possible to gain these only by eating their own poop and hence digesting the food twice.
Terminology
Both the rabbits and rodents have almost similar terminologies for the members of their families. A female rabbit is called a doe, so does a female rat. A male rabbit is called a buck, and a male rat is called with the same name too. Even their babies have similar names too. Babies of both species are called kittens. However, newborn babies of rats are sometimes called pinkies. It is because of the cute pink color they have at the time of their birth.
Both the baby rabbits and rats are born blind and deaf. Not only this, but they also have no fur and are entirely dependent on their mothers for feeding. Both the babies grow and become sexually mature at an early stage of their life.
Which Order Do Rabbits Belong to?
Rabbits belong to the Order Lagomorpha. The word lagomorph means hare shaped. The order includes medium-sized animals. Their evolutionary history is entirely different from that of rodents. Lagomorphs comprise the majority of the prey animals. Though some species are scavengers and eat the dead remains of other animals.
Characteristics of Lagomorphs
All the characteristics of lagomorphs can be easily studied through domestic rabbits. Keep a European rabbit in view, and you will observe it has all the basic properties of the group.
Lagomorphs have generally larger ears and hind legs that are quite strong. Nature gifted these two features to lagomorphs because they are prey in the food web. They have a great sense of listening to both low and high-frequency sounds and sensing dangers. They have mammary glands for feeding their babies. They have a cranium to which a structure called the postorbital process is partially attached. It is quite unique feature that is not found in other mammals. They are sensitive animals who always demand love and affection.
Other Animals Belonging to Lagomorpha
Order Lagomorpha has two families within it.
Family Leporidae
This family includes rabbits and hares. Hares have a body size larger than that of rabbits, with longer legs and ears. Rabbit fur doesn’t change its color and remains the same throughout the year. However, hares tend to change the color of their fur. Their color depends on the weather. During the Summer and the Spring season, the color of the fur can change from reddish-brown to several shades of gray. In Winter, the color becomes light and often turns white.
They differ in their tastes in plants as well. Rabbits prefer soft grass and hay as well as eat leaves, vegetables, and certain flowers. Hares like to eat twigs and small pieces of wooden bark. Rabbits make their homes underground in the form of tunnels. They form many interconnected tunnels, also called warren, while hares live on land.
A newborn baby rabbit, called a kit, is blind and deaf and has no fur. It depends entirely on its mother. While on the contrary, a newborn baby hare looks like a small mammal that has complete fur. It can see and hear and doesn’t depend on the mother for a long period of time. It starts moving within an hour of its birth.
Rabbits hide in their burrows when they sense any danger, and hares run away. Rabbits can be kept as pets, whereas hares can’t. Hares remain wild and are not domesticated. Both of them have thick fur and many other mechanisms for surviving the harsh cold.
Family Ochotonidae
This family is also called the pika family. These mammals are mostly found in the mountains of Asia and North America. They have a small round body with short limbs and large ears. They don’t have a visible tail.
Pika is also called a whistling hare because of the high-pitched sound it makes while going in its burrow. They eat the food of both the rabbits and the hares, including flowers, leaves, hay, and twigs. In winters, they store the dead bodies of birds in their burrows and feed on them as they hardly get anything to eat during harsh weather. Like other members of Lagomorpha, they are coprophagous and eat feces of their own as well as other animals.
Conclusion
Rabbits are lagomorphs and not rodents; both are entirely different orders of mammals. Although they were initially classified as ones, it would be scientifically wrong to call rabbits rodents now. They show some similarities like being fast breeders, coprophagous, and feeding their babies through the placenta in their wombs. However, the phylogenetic studies on both orders have clearly shown that they don’t share a common history.
They have different dental anatomy. Rabbits are obligate herbivores, whereas rodents may be either herbivores or omnivores. Rodents have baculum bones for efficient mating, while rabbits have no such bony structures. Rodents have long tails and short ears; rabbits, on the other hand, have short tails and large ears. All of these differences have forced the taxonomists to place rabbits, hares, and pikas in a separate order Lagomorpha.
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