The family Colubridae represents the largest and most widespread group of snakes in the world, encompassing nearly two-thirds of all known snake species. Colubrids are characterized by immense diversity in size, shape, color, and behavior, with over 2,000 species classified across hundreds of genera. Colubrids are found on every continent except Antarctica, successfully adapting to a vast array of environments from deserts to aquatic habitats.
Defining Characteristics of Colubrids
Colubrids are generally characterized by a set of shared anatomical features that distinguish them from other snake families. Like all snakes, they are limbless, but they specifically lack the vestiges of a pelvic girdle found in more primitive snakes like boas and pythons. Most colubrids possess a single row of wide scales, known as ventral scales, along their belly, which aid in locomotion. On the top of the head, they typically have nine large, plate-like scales.
Internally, many colubrids show a reduction or complete absence of the left lung. The teeth are generally solid and conical, arranged in rows along the jaw, though this feature varies significantly across the family. Unlike vipers or elapids, colubrids typically lack the advanced, front-facing, hollow fangs for rapid venom injection. The body forms range from small, slender, burrowing species to large, robust constrictors and long, arboreal climbers.
The Scope of Colubrid Diversity
The Colubridae family covers almost every ecological niche available to snakes. Many of the most commonly encountered and popular pet snakes belong to this single family.
North America is home to numerous examples, including the King Snakes (Lampropeltis), which are renowned for their vibrant patterns and their tendency to prey on other snakes, including venomous species. Rat Snakes (Pantherophis), like the popular Corn Snake, are slender, semi-arboreal climbers often found around human dwellings where they hunt small mammals and birds. Garter Snakes (Thamnophis) are among the most geographically widespread of all colubrids, frequently found near water and feeding primarily on amphibians, fish, and earthworms.
Rear-Fanged Anatomy and Safety Concerns
A subset of colubrids is classified as opisthoglyphous, meaning they possess a specialized venom delivery system known as “rear-fanged.” These species feature enlarged teeth located at the back of the upper jaw, which are often grooved to channel venom into a bite wound.
This system differs from the hypodermic-needle-like fangs of front-fanged snakes, which can inject venom quickly and deeply. Rear-fanged colubrids must typically hold onto and chew their prey to successfully introduce the venom from the rear teeth. This low-pressure delivery mechanism makes envenomation of humans highly inefficient during a quick, defensive bite.
For the vast majority of rear-fanged species, like the North American Hognose Snake, the venom is mild and poses little to no medical threat to humans. However, a few exceptions exist, such as the African Boomslang (Dispholidus typus) and Twig Snakes (Thelotornis), whose venoms are highly potent and have caused confirmed human fatalities. These dangerous exceptions emphasize the importance of caution, although they represent a tiny fraction of the overall colubrid family.
Ecology and Captive Care
Colubrids exhibit a wide range of ecological roles, from aquatic species that hunt fish to arboreal species that spend most of their lives in trees. Their diets are equally varied, including insects, eggs, amphibians, fish, lizards, birds, and mammals, depending on the species and its habitat. This flexibility in diet and habitat has contributed significantly to their global distribution and population success.
Many colubrid species are highly sought after in the pet trade due to their manageable size and relatively docile nature. The Corn Snake (Pantherophis guttatus) is a prime example, known for its adaptability to captivity and the wide array of color variations bred by hobbyists. General captive care for most colubrids involves providing a secure enclosure with a thermal gradient, allowing the snake to regulate its body temperature by moving between a warm spot of about 85–90°F and a cooler area.
A consistent supply of fresh water and appropriate substrate, such as aspen or cypress mulch, is important for maintaining hydration and ease of cleaning. Feeding typically consists of appropriately sized, pre-killed rodents, which aligns with the constricting habits of many common pet species like Rat Snakes and King Snakes.