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Altricial


In biology, altricial species are those in which the young are incapable of moving around on their own soon after hatching or being born. The word is derived from the Latin root alere, meaning "to nurse, to rear, or to nourish" and indicates the need for young to be fed and taken care of for a long duration. Species whose young are immediately or quickly mobile are called precocial.

In bird and mammal biology, altricial species are those species whose newly hatched/born young are relatively immobile, lack hair or down, are not able to obtain food on their own, and must be cared for by adults; closed eyes are common, though not ubiquitous. Altricial young are born helpless and require care for a specific amount of time. Among birds, these include herons, hawks, woodpeckers, owls, cuckoos and most passerines. Among mammals, marsupials and most rodents are altricial. Cats, dogs, and humans are some of the best-known altricial organisms.

At the opposite end of the spectrum are precocial animals in which the young have open eyes, have hair or down, have large brains, and are immediately mobile and somewhat able to flee from, or defend themselves against, predators. For example, with ground-nesting birds such as ducks or turkeys, the young are ready to leave the nest in one or two days. Among mammals, most ungulates are precocial, being able to walk almost immediately after birth. Beyond the precocial are the superprecocial animals, such as the megapode birds, which hatch with full flight feathers.

Different animals employ different precocial and altricial strategies; there is no clear distinction between the two states, and a wide range of intermediate states. The ability of the parents to obtain nutrition and contribute to the pre-natal and post-natal development of their young appears to be associated.


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Wikipedia

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