A lagomorph is a mammal belonging to the order Lagomorpha, a distinct group of animals that includes rabbits, hares, and pikas. The term “lagomorph” itself originates from Greek words meaning “hare form,” reflecting the common appearance of many members of this order.
Defining Features of Lagomorphs
A distinguishing feature of lagomorphs is their dentition, specifically the arrangement of their incisors. Unlike most mammals, lagomorphs have two pairs of upper incisors, with a smaller, peg-like pair located directly behind the larger, more prominent front pair. These continuously growing teeth are highly adapted for gnawing on plant material.
Their diet consists entirely of plant matter, making them obligate herbivores. To efficiently digest this fibrous material, lagomorphs employ a specialized digestive process known as hindgut fermentation. Food passes through the stomach and small intestine before fermentation occurs in the cecum, a large pouch at the beginning of the large intestine. This process allows them to extract maximum nutrients from tough plant fibers.
A unique aspect of their digestion is coprophagy, or re-ingestion of their own feces. After initial digestion, they produce soft, nutrient-rich fecal pellets called cecotropes, which they consume directly from the anus. This second pass through the digestive system allows for further absorption of vitamins and nutrients synthesized by gut bacteria. Their skeletal structure is also adapted for quick, powerful movements, particularly noticeable in the elongated hind limbs of rabbits and hares designed for hopping.
Lagomorphs Versus Rodents
Many people commonly mistake lagomorphs for rodents, yet these two orders of mammals are distinct. The most significant difference lies in their dental structure. Rodents possess a single pair of continuously growing upper and lower incisors, which they use for gnawing. In contrast, lagomorphs have the unique arrangement of two pairs of upper incisors, with the smaller second pair positioned behind the primary pair.
Beyond dentition, there are also differences in skull morphology. The skulls of lagomorphs have a fenestrated, or lattice-like, appearance due to numerous small openings in the bone. Rodent skulls lack these widespread perforations. These skeletal distinctions reflect separate evolutionary pathways, indicating that lagomorphs and rodents developed independently from different ancestral lines.
Their evolutionary lineage further clarifies their separation; while both groups are gnawing mammals, they are not closely related. Genetic and fossil evidence confirms that Lagomorpha and Rodentia diverged millions of years ago. Therefore, despite superficial similarities in size and some behaviors, lagomorphs are not a type of rodent.
Examples of Lagomorphs
The order Lagomorpha encompasses a variety of recognizable animals. Rabbits are a familiar example, known for their relatively short ears, soft fur, and burrowing habits. They are found across many continents and exhibit diverse adaptations to different environments.
Hares are another prominent group within lagomorphs, distinguished from rabbits by their longer ears, longer hind legs, and faster running speeds. Unlike rabbits, hares do not dig burrows but rather create shallow depressions, known as “forms,” in vegetation for shelter. Hares are also more precocial at birth.
Pikas represent a third type of lagomorph. These small, mountain-dwelling mammals have short, rounded ears and no visible tail. Pikas are known for collecting and storing vegetation in “haystacks” to eat during colder months.