Before discussing whether rabbits are mammals or not, let’s have a brief look at the method by which we classify the animals into different groups and subgroups, one of which is mammals.
Classification of Animals
The total number of animal species that have been identified so far is 8.7 million. Many more of the animals out there are still unidentified. In order to deal with such a large number, taxonomists have classified animals into groups and subgroups in which the animals which are more closely related to one another are placed together. When arranged in the form of a phylogenetic tree, each animal is seen relating to the others at some point.
All animals form a kingdom called ‘Animalia.’ The kingdom is further divided into different phyla. Some major phyla are Porifera, Cnidaria, Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda, Echinodermata, Hemichordata, and Chordata. The most developed of these animals are of the Phylum Chordata. The Chordates include animals of classes like fish, amphibians, reptiles, birds, and mammals. Each of these classes, let’s say mammals, are further divided into different Orders, Families, Genera, and Species.
What are Mammals?
All the animals which are members of the class ‘Mammalia’ are mammals. Scientists named them mammals because these animals are characterized by the possession of mammary glands to feed their young ones after birth, as the word mammal has been derived from a Latin term mamma, which means ‘breast.’ Some other features which are present in almost all mammals include the presence of hair or fur, sweat glands, 3 middle ear bones, non-nucleated red blood cells, and highly developed organs and organ systems.
Mammals are of three types:
- Monotremes: These mammals lay eggs that hatch, and the young ones come out of them. They later feed on the mother’s milk to fulfill their nutrition. The two living examples of monotremes, platypus and echidna, are exclusive to Australia and New Guinea, though they were thought to be distributed worldwide before. Monotrematum, an extinct monotreme, was found in South America in the old times.
- Marsupials: These are the pouched mammals. The females have a pouch or marsupium to keep their babies on their lower bellies. Babies are altricial and premature. After birth, the mother transfers the baby to her pouch. The baby feeds on the nipples inside the pouch and remains there until it’s fully mature. Examples of marsupials are kangaroos, opossums, koalas, wombats, wallabies, etc.
- Placentals: These mammals are characterized by the presence of the placenta, the vascular connection that forms between the mother’s womb and the baby in the womb to facilitate the exchange of oxygen, nutrients, and waste. In most placentals, a baby completes its development in the womb and is fully developed when born. Humans, monkeys, dolphins, whales, cats, dogs, and elephants all are placental mammals.
To Which Class of Animals Do Rabbits Belong?
Rabbits are mammals; to be more precise, they are placental mammals. The female rabbit keeps the babies in her womb until they are fully developed. During gestation, the babies are nourished through the placenta’s blood vessels. After their development is complete, the mother rabbit gives birth to many offspring called kittens at a time. Rabbits are altricial, which means that they are entirely dependent on their mothers after birth. Newborn rabbits are helpless on their own; they are born blind and without fur, even unable to move on their own.
Female rabbits, like all other mammals, have mammary glands or breasts. After the females give birth, baby rabbits feed on their mothers’ milk to keep themselves nourished. This is called weaning; it must be allowed until the baby bunnies are old enough to eat food by themselves. This usually happens anywhere between four and six weeks of their age. Apart from having mammary glands and placenta, the rabbit also qualifies all other properties one needs to be a mammal. It has fur, a set of sweat glands, RBCs without a nucleus, middle ear bones, and all of the other mammalian stuff as well, which has been mentioned earlier.
Taxonomy of Rabbit
Rabbit belongs to the class Mammalia of the phylum Chordata. Chordates are the most advanced animals on the planet. The subclass to which the rabbit belongs is Theria, and its division Eutheria, which are also called placental mammals. There is a total of 20 different orders of placental mammals. Out of these, rabbit belongs to the order Lagomorpha.
Lagomorpha has three families, out of which Leporidae and Ochotonidae are the living families. Rabbits and hares belong to the family Leporidae. There are 11 genera in this family, out of which only one genus, Lepus, is of the hares and the other 10 are of the rabbits. These are Brachylagus, Bunolagus, Caprolagus, Nesolagus, Oryctolagus, Pentalagus, Poelagus, Pronolagus, Romerolagus, and Sylvilagus. Although the common name for these small mammals is a rabbit, and people also call the young rabbit a bunny, the total number of rabbit species is 29. The common representative species of rabbits is the European rabbit (Oryctolagus cuniculus).
Best Known Species of Rabbits
Although the average number of the rabbit species found in the records is 29, this number varies in some books. This is because rabbits are extremely diverse animals. For example, 17 species of Sylvilagus or cottontails are found in North and South America alone. In addition, there are as many as 305 breeds of domestic rabbits; almost all of these have been selectively bred from the world’s oldest known rabbit, the European rabbit (Oryctolagus cuniculus). The European rabbit is native to Southwestern Europe and Northwestern Africa but is found all over the world today, except in Antarctica and Sahara.
Some other common and best-known species of rabbits are:
- Eastern cottontail (Sylvilagus floridanus), the most common species of cottontails found in North and South America
- Pygmy rabbit (Brachylagus idahoensis) is North America’s smallest rabbit species.
- Swamp rabbit (Sylvilagus aquaticus) is a large rabbit living in the wet lowlands of Mississippi.
- New England Cottontail (Sylvilagus transitionalis) is the only rabbit native to New England.
- Volcano rabbit (Romerolagus diazi), the world’s smallest rabbit found on the volcanoes of Central Mexico, is therefore named as volcano rabbit.
- Desert Cottontail (Sylvilagus audobonii), long-eared rabbits common in the White Sands of New Mexico.
- Riverine rabbits (Bunolagus monticularis) are found along the dry riverbeds of the Karoo region in South Africa.
Are Rabbits Rodents?
No, rabbits are not rodents; in fact, both belong to two different orders of mammals. Rodents include rats, mice, squirrels, hamsters, chipmunks, beavers, guinea pigs, etc. All these animals are part of the order Rodentia which is actually the largest order of mammals comprising more than 2050 species of rodents; many more are thought to be present.
On the other hand, Rabbits belong to the entirely separate order Lagomorpha. This is because they are more closely related to hares and pikas(both are Lagomorphs) than rats and hamsters. The reason behind the confusion between rabbits and rodents is the similarities that are often seen between them. This is also why rabbits and hares were originally classified alongside rodents in the early times. However, they were later studied to be different and were separated from the rodents and placed in a separate group in 1912.
Both the rabbits and rodents are placental mammals, have continuously growing incisor teeth, are fast breeders, and produce a litter. BUT!! Rabbits are herbivores, rodents, maybe herbivores or omnivores. Rabbit has four incisors; rodents have two. A rabbit has long ears and a short tail; a rat has shorter ears and a long tail. All rabbits are coprophages, but not all rodents are. Rodents have shorter gestation periods, about 21 to 23 days; most rabbits have a gestation period of 31 to 33 days. There are also many other differences that prove that rabbits are not rodents.
General Characteristics of a Rabbit
Although the term rabbit is very broad and consists of several species, all rabbits generally exhibit some common characteristics. The behavior of wild and domestic rabbits may differ slightly as they become adapted to their environment, but both physiological and behavioral characteristics are the same. As obvious, their basic body plan and internal body structures are also identical. So let’s have a look at some of the salient characteristics of rabbits.
All the domestic rabbits have been bred from European rabbits that were indigenous to Europe and Africa, but now they are found almost all over the world in every kind of environment. Woodlands, grasslands, jungles, plains, deserts, marshes, and poles are all the habitats of rabbits. Although rabbits are not effective bearers of heat, those living in the arid and hot climates have certain adaptations to bear the temperature extremes. Pet rabbits, on the contrary, require a controlled environment with appropriate temperature and humidity to survive for longer periods of time.
Most rabbits are ground dwellers. Wild rabbits, especially the does dig tunnels into the ground to make their homes; warrens feature spaces for nesting and staying. They also have a number of exits in case the rabbits need to escape quickly. Warrens can be as deep as 3 meters below the ground. In addition, the open environment of the forests and meadows helps them detect predators and escape.
Rabbits are small mammals with an average size of 40 centimeters in length. The average weight of a domestic rabbit is 6 pounds. The smallest rabbits weighing less than a pound include the pygmy rabbits and the volcano rabbits. These grow to the size of 11 to 30 centimeters in length. Some other small breeds include Netherland dwarf, English Angora, Dwarf Hotot, American Fuzzy Lop, Jersey Wooly, Holland Lop, and Lionhead Rabbit.
Flemish Giant Rabbit is the largest rabbit breed in the world. It is large enough to be mistaken for a dog. It has an average weight of 15 pounds. The longest one recorded by the Guinness World Records is 129 cm or 1.29 m. Some other large rabbit breeds include Continental Giant, Spanish Giant, Hungarian Giant, Blanc de Bouscat, French Lop, Silver Fox, and Giant Papillon.
Rabbits have an egg-shaped body with a cute and downy appearance. The face of a rabbit is almond-shaped. This small mammal has long whiskers, and large ears, no larger than that of a hare. The long ears of rabbits are an adaptation that helps them in detecting predators in the wild. In addition, the rabbits have a small puff-like tails. In some rabbits, the tail is nothing other than a white ball of cotton. Therefore we call these rabbits cottontails. However, the tail of European rabbits is generally brownish in color with a white underside.
The long powerful hind legs help the rabbit to escape from predators in the wild. In addition, pet rabbits have generally long fur, which is more soft and even, giving them an attractive appearance. The fur of wild rabbits is brown in color and is coarser. Although wild rabbits’ body proportions and posture are quite consistent, those of pet rabbits may vary as they are exposed to different domestic environments.
Unlike most of the other mammals, the rabbit begins breeding at a very young age. A male rabbit is sexually mature after 8 months of their age. A doe matures sexually when she is 5 to 6 months of age. The release of the egg is stimulated by sexual intercourse. The gestation period is about a month; the rabbit can be pregnant again after a few days. Each year, a rabbit is pregnant 3 to 4 times on average. It can continue to conceive for 4 years.
The female rabbit gives birth to 1 to 12 baby rabbits called kittens. On average, these are five in number. All of the babies which are born at the same time are collectively termed as litter. The kittens, when born, are naked, blind, and unable to move on their own. Mother rabbit feeds the young ones on her milk.
Rabbits are hindgut fermenters. Their gut is longer than ours. The digestion is mediated by the symbiotic bacteria which reside in their cecum, where the chewed plant material collects. The cecum is a large blind-ended sac present at the beginning of the large intestine. The microflora of the rabbit’s stomach can digest fiber efficiently, but proteins, vitamins, and minerals are partially digested and thus wasted in the feces.
Rabbits solve this problem by having a double digestion process. They produce two types of feces: hard droppings, which are the actual wastes, and soft black viscous pellets, which are rich in nutrients. Rabbits immediately eat this soft feces form (caecotrophs). The process is called coprophagy. Therefore, the hard feces we usually found in the rabbit’s litter box are not eaten by them.
Rabbits eat only plants and plant material. Therefore they are called Herbivores. They cannot eat meat as their digestive systems are highly specialized to digest plants. In addition, rabbits produce certain cellulose digesting enzymes to digest fiber in plants which we humans can’t produce.
Wild rabbits feed on grass, leaves, twigs, the bark of the trees, seeds, fruits, and vegetables found in the wild. The diet for a pet rabbit, on the other hand, varies slightly. Ideally, it should consist of fresh water and hay in large quantities. Hay is rich in fibers and thus important to keep your bunny’s health in check. In addition, it wears down the continuously growing teeth of the rabbit and also keeps its digestive system in good shape. Apart from hay, rabbits also feed on pellets, leafy greens, and vegetables.
Being hunted in large quantities, both by wild animals and humans, the population size of many species of bunnies is falling towards the decline continuously. According to IUCN, nearly half of the world’s rabbit species are endangered (at the risk of becoming extinct), especially due to habitat destruction.
Small rabbit breeds like pygmy rabbit and volcano rabbit are at greater risk of extinction. The only two black striped species of rabbits are also in the IUCN red list of vulnerable species; these are Annamite striped rabbit (Nesolagus timminsi) and Sumatran striped rabbit (Nesolagus netscheri). Even the population of some less known species of European rabbits is known to be declining day by day.
The Lagomorph specialist group (LSG) of IUCN is currently working to protect these and other species of rabbits and hares.
Importance of Rabbits
Apart from being kept as a pet due to their quiet manner, rabbits are being used by us for a variety of other purposes too. It indirectly also causes some harm to humans.
Rabbits (both the wild and domestic rabbits) have been economically important to mankind for decades. Hunting wild lagomorphs just for fun or to obtain their meat and fur is common among hunters until this very day. Rabbit meat is still a popular part of the diet in many countries with its exquisite flavor. It is, in fact, a part of different cultures, for example, the popular rabbit stew ‘Hasenpfeffer,’ which is found in the Dutch and German cuisines.
European rabbits are the most common domestic rabbits found in many parts of the world. Domestic rabbits are kept for food and fur. Rabbit fur is used to make furry coats, sweaters, hats, felt, etc. The high-quality wool, ‘Angora wool,’ is also obtained from a rabbit. The original time of rabbit domestication is a point that requires discussion. According to the fossil record and historical documentation available, some archaeologists believe that rabbits have been hunted for meat and fur since the last ice age.
In terms of benefits, rabbits play two important roles in balancing our ecosystem. Firstly, they keep wild vegetation growth in check, especially that of invasive plants. Secondly, they are the prey animals and serve as food for different other animals. Without them, a number of carnivores will probably starve.
Rabbits can also be the source of diseases, for example, rabbit fever in humans. This disease is called tularemia and does not occur naturally in people. However, if a person eats rabbit meat that is already infected with the bacteria Francisella tularensis, he can develop rabbit fever. The most common symptoms of this disease are chills followed by high fever and swollen lymph nodes.
Importance in Scientific Research
Rabbits are the most important laboratory animals which are being used for medical and scientific purposes. These are the disease models for the development of therapeutics. In Microbiology, they are used as animal models to test different biologicals like vaccines. In addition, they are being used in Medical fields to produce and test monoclonal and polyclonal antibodies.
Rabbits are mammals as they belong to the class Mammalia of Chordates. They are placental mammals and give birth to live young ones. They consist of 10 genera and 29 species. European rabbits are the representatives of the family. The body of the rabbit is egg-shaped with long ears and a short tail. These small mammals are hind-gut fermenters and feed only on plants.