Habit, equivalent to habitus in some applications in biology, refers variously to aspects of behaviour or structure, as follows:
In zoology (particularly in ethology), habit usually refers to aspects of more or less predictable behaviour, instinctive or otherwise, though it also has broader application. Habitus refers to the characteristic form or morphology of a species.
In botany, habit is the characteristic form in which a given species of plant grows (see plant habit).
In zoology, habit (not to be confused with habitus as described below) usually refers to a specific behavior pattern, either adopted, learned, pathological, innate, or directly related to physiology. For example:
the [cat] was in the habit of springing upon the [door knocker] in order to gain admission...
If these sensitive parrots are kept in cages, they quickly take up the habit of feather plucking.
The spider monkey has an arboreal habit and rarely ventures onto the forest floor.
The brittle star has the habit of breaking off arms as a means of defense.
Mode of life (or lifestyle, modus vivendi) is a concept related to habit, and it is sometimes referred to as the habit of an animal. It may refer to the locomotor capabilities, as in "(motile habit", sessile, errant, sedentary), feeding behaviour and mechanisms, nutrition mode (free-living, parasitic, holozoic, saprotrophic, trophic type), type of habitat (terrestrial, arboreal, aquatic, marine, freshwater, seawater, benthic, pelagic, nektonic, planktonic, etc.), period of activity (diurnal, nocturnal), types of ecological interaction, etc.
The habits of plants and animals often change responding to changes in their environment. For example: if a species develops a disease or there is a drastic change of habitat or local climate, or it is removed to a different region, then the normal habits may change. Such changes may be either pathological, or adaptive.
In botany, habit is the general appearance, growth form, or architecture. For example:
Many species of maple have a shrubby habit and may form bushes or hedges rather than trees.