The term “herps” is a common shorthand for Herpetofauna, which includes the vertebrate classes Amphibia and Reptilia (frogs, snakes, turtles, and salamanders). Though they are distinct evolutionary groups, scientists traditionally study them together for historical and practical reasons. This grouping persists because they share certain biological traits and ecological roles in various ecosystems.
Defining Amphibians
Amphibians are vertebrates in the Class Amphibia, characterized by a “dual life” adaptation relying on both aquatic and terrestrial environments. Their defining characteristic is a biphasic life cycle involving metamorphosis. The cycle begins with shell-less eggs laid in water, which hatch into aquatic larvae (tadpoles) that breathe with gills.
The larvae then undergo metamorphosis, developing limbs and lungs to become air-breathing, terrestrial adults. Amphibians possess thin, permeable skin that must be kept moist for cutaneous respiration (gas exchange through the skin). This reliance on moisture for survival and reproduction means they are rarely found in dry habitats.
The Class Amphibia is divided into three main groups: Anura, Urodela, and Gymnophiona. Anura includes frogs and toads, the most numerous amphibian order, known for powerful hind legs adapted for jumping. Urodela comprises salamanders and newts, which typically maintain a tail and have four limbs of roughly equal size. Gymnophiona are the caecilians, a lesser-known group of legless, burrowing amphibians that superficially resemble large earthworms or snakes.
Defining Reptiles
Reptiles are vertebrates in the Class Reptilia that have fully adapted to a terrestrial existence. The key evolutionary advancement allowing this shift is the amniotic egg. This specialized egg contains membranes that protect and nourish the embryo, providing its own aquatic environment and eliminating the need to return to water for reproduction.
Reptiles (snakes, lizards, turtles, and crocodilians) reproduce via internal fertilization, and most species lay leathery-shelled eggs on land. Their skin is covered in keratinous scales or scutes, which provides a waterproof barrier preventing desiccation. This enables them to thrive in arid and diverse terrestrial habitats, contrasting sharply with the moist skin of amphibians.
Reptiles are grouped into four major living orders:
- Squamata: The largest group, encompassing all lizards and snakes, characterized by movable quadrate bones allowing for wide jaw movement.
- Testudines: Includes turtles and tortoises, defined by their bony or cartilaginous shell.
- Crocodilia: Includes crocodiles, alligators, caimans, and gharials, which are large, semi-aquatic predators.
- Rhynchocephalia: A small order containing only the tuatara, found exclusively in New Zealand.
The Shared Science of Herpetology
The study of both reptiles and amphibians is known as herpetology. The primary biological link connecting these two distinct classes is ectothermy: their reliance on external sources to regulate body temperature. Ectothermic animals, often called “cold-blooded,” manage heat by basking in the sun or seeking shade, rather than generating a steady internal temperature.
This shared characteristic of ectothermy means that many of the biological principles, ecological pressures, and research methods used to study one group are relevant to the other. The term “herp” itself derives from the archaic classification system of Carl Linnaeus, who initially grouped all reptiles and amphibians into a single class based on their external appearance and ectothermic nature. Though modern taxonomy now recognizes them as separate classes, the tradition of studying them under the umbrella of herpetology has persisted within the scientific community.
Why Herps Matter
Herpetofauna are integral components of global ecosystems, playing important roles in the food web as both predators and prey. Many species, such as frogs, are voracious insectivores that help control pest populations, which is beneficial for both natural environments and human agriculture. They are also a significant food source for various birds, mammals, and other reptiles, connecting different trophic levels within their habitats.
Amphibians, in particular, are regarded as highly sensitive bioindicators of environmental health. Their permeable skin readily absorbs substances from the environment, making them vulnerable to pollution, habitat degradation, and climate change. Monitoring the health and population stability of amphibians and, to a lesser extent, reptiles provides scientists with visible, early warnings that an ecosystem’s quality is deteriorating. Their presence often signifies a healthy environment, while their decline indicates underlying ecological problems.