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Lagomorph

Lagomorpha

Lagomorphs are small to medium-sized terrestrial mammals that resemble large rodents in appearance. They belong to the order Lagomorpha, which includes rabbits, hares, and pikas or conies. 

These animals are found on nearly all continents except Antarctica and are exclusively terrestrial. They thrive in underground burrows for most of the day, usually feeding on plants, while a few, like collared pikas, consume decaying carcasses and fecal matter.

Description

Lagomorphs are endothermic mammals with four limbs, characteristic body hair, and mammary glands. Unlike most small mammals, they possess a postorbital process fused to the skull and a smooth-surfaced cerebrum. They exhibit a unique characteristic among terrestrial mammals: the females are generally larger than the males.  

Although lagomorphs and rodents fall under the same grandorder, Glires, they have some major differences. Lagomorphs have four incisors (two large incisors and two smaller peg teeth behind them), whereas rodents have two. The incisors are structurally different in both groups and grow continuously in rodents, whereas in lagomorphs, all the teeth show constant growth. 

Unlike rodents, lagomorphs do not have rubbery paw pads; their paw bottoms are covered with fur (like red pandas). They also lack canines (like rodents), and a large space called diastema separates the incisors from the first cheek tooth.

Size

The largest living lagomorph is the European brown hare (Lepus europaeus), which measures 60 to 75 cm (1 ft 11 to 2 ft 5 inches) in body length and 7.2 to 11 cm (2.8 to 4.3 inches) in tail length. It typically weighs between 3 and 5 kg (6 and 11 lbs).

In contrast, the smallest lagomorph, the tiny American pika (Ochotona princeps), measures only 6 to 8 inches.

Pikas

They are about 15 cm (6 inches) long, with four legs (nearly equal in length) and no external tail. They have greyish brown, silky fur and tiny, round ears.

Hares

These medium-sized mammals range from 40 to 70 cm (16 to 28 inches). Their hind legs are longer and more powerful than the fore legs, and their ears are characteristically long (20 cm or 8 inches).

Like pikas, hares are usually greyish-brown in color but often turn white in winter. 

Rabbits

They are usually smaller than hares and measure 20 to 50 cm (8 to 20 inches) in body length. Like hares, they have longer and sturdier hind legs, shorter forelegs, and a short tail.

They are typically brown, buff, or grey, though two species, the Annamite and the Sumatran striped rabbits, have stripes on their bodies.

Taxonomy

The order Lagomorpha derives its name from the Greek words lagos, meaning hare, and morphe, meaning form, referring to the hare-like appearance of its members.

Currently, 109 living species of lagomorphs are divided into two families: Leporidae (with 42 species of rabbits and 33 species of hares) and Ochotonidae (with 34 species of pikas).

Evolution and Fossil Records

The evolution of lagomorphs is still poorly understood. 

Distribution and Habitat

Rabbits and hares are found in North America, Europe, central and southern Africa, and also in the Indian subcontinent, Sumatra, and Japan. In contrast, pikas inhabit the semi-deserts of Central Asia, China, and parts of Western North America. However, these lagomorphs are generally not seen in Antarctica, the West Indies, Indonesia, Madagascar, or the southernmost regions of South America.

The pikas occupy broken rock fragments (scree), burrows of mountainous regions, and alpine meadows, whereas rabbits and hares have a broader habitat range, including agricultural lands, forests, swamps, deserts, mountains, and grasslands. Cottontails and hispid hares live in special nests called forms that are usually built under bushes.

Lifespan

While rabbits in the wild live anywhere between one to eight years, those in captivity survive for seven to ten years. Pikas, in contrast, live for around seven years, with rock-dwelling species living longer than the burrowing ones.

Diet

They are strictly herbivorous, feeding on grass, herbs, forbs, hay, straw, and other plant materials, unlike rodents, many of which eat both meat and vegetable matter. 

When domesticated, rabbits eat fresh fruits and vegetables, such as carrots, cabbage, and spinach. Collared pikas often consume the carcasses of birds and the feces of other animals.

Behavior

Rabbits and hares are primarily nocturnal, emerging from their burrows only during the dark. In contrast, pikas are diurnal and forage mostly in daylight. 

Sociality

Rock-dwelling pikas are mostly solitary and contribute one or two small litters to the existing population annually. In contrast, those living in burrows are gregarious and give birth to multiple large litters throughout the year.

Although most rabbits are colonial and feed in small groups, hares are usually solitary and do not usually socialize.

Feeding and Digestion

Lagomorphs use their four incisors to grind the plant material they consume. Since cellulose is difficult to digest, they ferment the fiber in the caecum (part of the gastrointestinal tract) and expel the fermented material as greasy packets called cecotropes (cecotrophy). They reingest these pellets to absorb the nutrients in the small intestine.

Reproduction and Life Cycle

Lagomorphs that spend most of their time underground breed multiple times year-round, producing large litter. 

Rabbits and pikas, known as kits, are born after a short gestation period of about one month. These kits are altricial, meaning they are born with closed eyes and ears without fur. In contrast, hares (leverets) are born after a relatively long gestation period, with each litter comprising a small number of precocial young. These newborns have open eyes and ears and are fully furred.

Since the young do not require constant attention, the mother leaves them and can mate and get pregnant almost immediately after giving birth. She returns only at intervals to feed them with extremely nutritive milk. Sometimes, the mother feeds the litter only once daily, but they grow rapidly and are weaned within a month. 

Predators

Raccoons, snakes, eagles, cats, owls, and hawks are natural predators of lagomorphs.

Adaptations

To shield themselves from the harsh cold during winter, pikas often collect hay in bulk (hay piles) and store it in their burrows for warmth.

References Article last updated on 8th June 2024
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