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Reptile Terms and Abbreviations

This page is intended to aid readers in understanding Reptile Terms and Abbreviations used in herpetology.

x.x.x – Used to designate the sex of the animals that you have. The first number is for males, the second for females, and the third (if used) is used for unknown/unsexed animals. For example, 2.1 is 2 males, 1 female and 2.1.4 would mean 2 males, 1 female, and 4 unknown/unsexed animals.

Arboreal – Tree dwelling reptile.

Adaptation – An inherited (genetically controlled) characteristic of an organism that helps it to survive and reproduce in the environment it inhabits. These are often interpreted as evolutionary changes in response to selection pressures present in that environment.

Amniote – An animal that produces an embryo within a sac that contains amniotic fluid. Amniotes include turtles, lizards, snakes, tuataras, crocodilians, birds, and mammals.

BCC – Boa Constrictor Constrictor.

BCI – Boa Constrictor Imperator.

BP – Ball Python.

BRB – Brazilian Rainbow Boa.

Carnivorous – Said of an animal which primarily eats other animals.

Caudal – Referring to the tail.

CB – Captive Born.

CBB – Captive Bred and Born.

Cloaca – A body opening that serves both for excretion and for the reproductive organs.

Clutch – A group of eggs that is laid in the same place at the same time (or nearly the same time), and will hatch at the same time.

Colubrid – A snake from the family Colubridae.

Constrictor – A snake that kills its prey by grabbing the animal and throwing two or three coils around it. The force of constriction (squeezing) prevents the prey from breathing, and it usually dies within seconds. The snake can then relax its grip and swallow the animal head-first.

Crepuscular – Active during the evening and early morning hours.

Cryptic coloration – A pattern of colors that makes an animal hard to see. It may be a pattern that is similar to the background on which the animal lives, or one that seems to break up the animal’s outline (also called “disruptive coloration”)

Cycling – The recurring reproductive phase, triggered by hormonal changes triggered by environmental cues. May occur on an annual basis, or a more or less frequent basis.

Diurnal – Active during the day.

Dorsal – Referring to features on the back or along the spine of the animal.

Ectotherm – An animal whose body temperature varies with the temperature of its surroundings (also called cold-blooded).

Endotherm – An animal that maintains its body temperature at a relatively constant level by physiological means regardless of the temperature of the environment (also called warm-blooded).

ETB – Emerald Tree Boa.

F/T – Fully Thawed.

Fertilization – When a sperm from a male penetrates the ova of a female. In oviparous species, fertilization occurs when the sperm meet the ova as they pass through the oviduct, a passage which also layers the outside of the egg with calcium to form a shell.

Follicle – A small bodily cavity or sac; any small spherical group of cells containing a cavity. pl. follicles. 2. small egg-containing sacks found in the female ovary. In fertile human females, one follicle will become dominant and release a mature egg (ovulate) during every cycle. In oviparous reptile species, several mature eggs will be produced, depending on the species and the individual.

Gestation – The period of time between mating and the birth of the young.

Gravid – Said of females when they are carrying fertilized eggs.

GTP – Green Tree Python.

Habitat – The kind of place where a plant or animal naturally lives.

Herpetology – The study of the biology and evolution of amphibians and reptiles.

Lateral – Referring to the sides of the body.

Live Birth – In reptiles, this is when the eggs hatch while still inside the female, and the young soon emerge alive. The young do not obtain nutrients from their mother while in the reproductive tract, as is the case with most mammals. A condition known as oviviviparous.

Litter – The offspring of a birth.

Nest – The burrow or pallet dug by the female in which to deposit her eggs.

Nocturnal – Active at night.

Oviparous – Reproduces by laying eggs (Pythons).

Ovoviviparous – Reproduces by eggs which remain in the mother’s body until they are ready to hatch. When the young emerge, they are born live, with only a membrane to break out of (Boas).

P/K- Pre-killed.

POS – Post Ovulation Shed.

Resorbtion– Some female animals can resorb fully developed eggs. What causes resorbtion in female reptiles is not known, so there is no known way to trigger nor prevent it.

Sexual Dimorphism – Refers to a species where the males and females are different in appearance. This can be a difference in size, or in other visual features.

Slug – An infertile egg.

Substrate – The surface on which a reptile lives and moves on (newspaper, paper towels, aspen shavings, Repti-bark, etc.)

Terrestrial – Land dwelling reptile.

UTH – Under the tank heater.

Vent – The cloaca of an animal; in reptiles this opening may also serve the reproductive organs. It is seen as a marker of where the body ends and the tail begins, which is hard to determine in some animals, such as snakes.

Ventral – Referring to the underside of an animal, the “tummy” side.

Vestigial – Remaining in a species only in a much reduced or useless state. Vestigial body parts or organs are evidence of parts that the ancestors of an animal had, but that the modern animal no longer needs or uses. For example, the Rosy Boa bears vestigial traces of the legs of its lizard ancestors.

Viviparous – Reproducing by giving birth to live young.

WC – Wild Caught


  • Blumen Boas (2016), “Reptile Terms and Abbreviations” (Accessed online @