Glossary: G

gallery forest

Luxuriant forest lining the banks of waterways.

game species

a species that is hunted recreationally for food or sport. Game species typically refers to species for sport, not as part of subsistence hunting.

gamma diversity

See diversity - gamma.


a bundle of nervous tissue containing many synapses and cell-bodies and contained within a sheath of connective tissue. Most ganglia (plural) occur outside of the central nervous system.

gas exchange

the process of exchanging gases from the environment with gases resulting from metabolism inside an animal's body across a gas exchange surface, such as the exchange surfaces of gills and lungs.


Cells lining the gastrovascular cavity. Synapomorphy of Scyphozoa+Cubozoa+Anthozoa.


a dormant, tough-coated cluster of cells produced by freshwater sponges for development in more favorable conditions.

generation (or generation time)

A period of time characteristic of an animal species and/or population that can be calculated as: The average age of parents in the population (used in the criteria for the new (1996) IUCN Red Data List categories), or the average age at first breeding


Referring to the genetic make-up of an organism.

See Also: phenotype
genus (plural genera)

A taxonomic division that generally refers to a group of animals which are similar in structure and descent but are not all able to breed among themselves. For example, the lion, leopard and tiger all belong to the genus Panthera.


eating clay or minerals as an essential addition to nutrition, such as to obtain mineral nutrients or to neutralize toxins in the diet. This includes the use of naturally occurring salt or mineral licks.


To begin to grow.


The process of carrying young inside the body before birth; the period from implantation of the embryo in the uterus to birth.

gibber desert or plains

Large areas in Australia covered by small, rounded pebbles, rocky ranges and low scrubby vegetation.

gill slits

Paired openings that allow movement of water from the pharynx to the exterior of the organism. Synapomorphy of the Chordata+Hemichordata.


pelvic and pectoral girdles are the portion of vertebrate skeletons made up of the pelvic bones (pelvic girdle) and the scapula and clavicle (pectoral girdle).


Any of the usually paired organs in animals that produce reproductive cells (gametes). These include female ovaries, which produce eggs, and male testes, which produce sperm. Gonads also secrete hormones that influence secondary sexual characteristics.


Animals in which the sexes are separate, each individual being unisexual, either male or female, such as in most vertebrates.


the medusae of some hydroids (Class Hydrozoa) which are reduced to gonadal tissue and do not detach.


the genital pore found in many invertebrates.

gran chaco

The Gran Chaco is a flat plain in the region of northern Argentina, southeastern Bolivia and western Paraguay and with a mosaic of vegetation types including thorn forest, savanna, marsh and gallery forest.


an animal that mainly eats seeds


An herbivore that feeds on grasses (compare browser).


Tending to associate with other animals of its kind; habitually living with other animals of its kind.

group defense

an anti-predator adaptation in which animals form groups primarily in order to protect themselves from predators, both through increased vigilance and combined aggression.


excrement of seabirds or bats

guard hair

Part of the coat of some animals consisting of longer, stiffer hairs which lie outside and support the warmer, softer underfur.