amphibians: A group of animals that includes frogs, salamanders and caecilians. Amphibians have backbones and can breathe through their skin. Unlike reptiles, birds and mammals, unborn or unhatched amphibians do not develop in a special protective sac called an amniotic sac.
bacteria: (singular: bacterium) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals). Bacteria are one of the three domains of life on Earth.
birds: Warm-blooded animals with wings that first showed up during the time of the dinosaurs. Birds are jacketed in feathers and produce young from the eggs they deposit in some sort of nest. Most birds fly, but throughout history there have been the occasional species that don’t.
caecilian: A type of amphibian that has no legs. Caecilians have ring-shaped folds of skin called annuli, small eyes covered by skin and sometimes bone, and a pair of tentacles. Most of them live underground in the soil, but some spend their entire lives in water.
chytridiomycosis: A disease caused by fungi (Batrachochytrium dendrobatidis and B. salamandrivorans). This disease is a major killer of amphibians, especially frogs, and appears to be responsible for the extinction of many amphibian species in recent years.
climate change: Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.
cold-blooded: Adjective for an animal whose body temperature varies with that of its environment.
environment: The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of things in the vicinity of an item of interest).
extinction: The permanent loss of a species, family or larger group of organisms.
fungus: (plural: fungi) One of a group of single- or multiple-celled organisms that reproduce via spores and feed on living or decaying organic matter. Examples include mold, yeasts and mushrooms.
gills: The respiratory organ of most aquatic animals that filters oxygen out of water. Fish and other water-dwelling animals use gills to breathe.
habitat: The area or natural environment in which an animal or plant normally lives, such as a desert, coral reef or freshwater lake. A habitat can be home to thousands of different species.
infection: A disease that can spread from one organism to another. It’s usually caused by some type of microbe.
insect: A type of arthropod that as an adult will have six segmented legs and three body parts: a head, thorax and abdomen. There are hundreds of thousands of insects, which include bees, beetles, flies and moths.
larvae: Immature insects that have a distinctly different form (body shape) than when they are adults. For instance, caterpillars are larval butterflies and maggots are larval flies. (Sometimes this term also is used to describe such a stage in the development of fish, frogs and other animals.)
mammal: A warm-blooded animal distinguished by the possession of hair or fur, the secretion of milk by females for feeding their young, and (typically) the bearing of live young.
metamorphosis: A dramatic change from one stage in an animal’s life history to the next, such as the process by which a tadpole becomes a frog or the changes that transform a caterpillar into a butterfly.
mucus: A slimy substance produced in the lungs, nose, digestive system and other parts of the body to protect against infection. Mucus is made mainly of water but also includes salt and proteins such as mucins. Some animals use mucus for other purposes, such as to move across the ground or to defend themselves against predators.
oxygen: A gas that makes up about 21 percent of Earth’s atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).
population: (in biology) A group of individuals (belonging to the same species) that lives in a given area.
scourge: A person or other organism that inflicts pain or threatens the success and wellbeing of others nearby.
species: A group of similar organisms capable of producing offspring that can survive and reproduce.
threatened: (in conservation biology) A designation given to species that are at high risk of going extinct. These species are not as imperiled however, as those considered “endangered.”
vertebrate: The group of animals with a brain, two eyes, and a stiff nerve cord or backbone running down the back. This group includes amphibians, reptiles, birds, mammals and most fish.