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(Redirected from Altricial)
Altricial means "incapable of moving around on its own soon after hatchling", where the young "require care and feeding by the parents after hatching." [Canadian Oxford, 1991]
In bird and mammal biology, 'altricial' species, or 'altrices', are those whose newly hatched or born young are relatively immobile, have closed eyes, lack hair or down, and must be cared for by the adults. Altricial young are born helpless and require care for a comparatively long time. Among birds, these include, for example, herons, hawks, woodpeckers, owls and most passerines. Rodents and marsupials are altricial, as are gray wolves.
On the opposite end of the spectrum are precocial animals in which the young have open eyes, have hair or down, large brains and are immediately mobile and somewhat able to defend themselves against predators. For example, with birds that nest on the ground, such as ducks or turkeys, the young are ready to leave the nest in one or two days. Similarly, butterflies and bees, elephants and horses, monkeys, donkeys and also wilderbeast; they are all able to fend for themselves almost immediately and so they are precocial.
Both altricial and precocial come from the same Latin root as the word "precocious" or "praecox", implying late or early maturity, and "to nourish." It makes reference to the need for extensive parental care required before fledging in altricial species.
Differerent animals employ different precocial or altricial strategies. It hinges on the ability of the female to contribute to the pre-natal and post-natal development of their young. Precocial females are able to provide protein-rich eggs and such their young hatch in the fledgling stage - able to protect themselves from predators (cf. ducks or turkeys) and the females have less involvement post-natal (think turtle eggs). Ostrich eggs are so large, that they are as large as an adult ostrich brain. Altricial females are somewhat less able to contribute nutrients in the pre-natal stage; their eggs are smaller and their young still in need of much attention and protection from predators.
The two strategies result in different brain sizes of the newborns compared to adults. Precocial animals' brains are large at birth relative to their body size, hence their ability to fend for themselves. However, as adults, their brains are not much bigger or more able. Altricial animals' brains are relatively small at birth, thus their need for care and protection, but their brains continue to grow. As adults, altricial animals end up with comparatively larger brains than their precocial counterparts. Thus the altricial species have a wider skill set at maturity.
Humans (and parrots) have developed a strategy comprising both altricial and precocial characteristics. The young are precocial: they have hair/down, eyes are open, and yet are immobile and require great investiture by the parents to protect them from predators and to provide nutrients to raise them to maturation. Humans (and parrots) have relatively large brains at birth, but brain size nonetheless continues to grow substantially to maturity.
★ The eight recognized modes (or categories) of development, ranging from full precocity to altriciality are discussed in Standford's: Precocial and Altricial at stanford.edu/group/stanfordbirds/text/essays/Precocial_and_Altricial.html. [1]".
Altricial means "incapable of moving around on its own soon after hatchling", where the young "require care and feeding by the parents after hatching." [Canadian Oxford, 1991]
In bird and mammal biology, 'altricial' species, or 'altrices', are those whose newly hatched or born young are relatively immobile, have closed eyes, lack hair or down, and must be cared for by the adults. Altricial young are born helpless and require care for a comparatively long time. Among birds, these include, for example, herons, hawks, woodpeckers, owls and most passerines. Rodents and marsupials are altricial, as are gray wolves.
On the opposite end of the spectrum are precocial animals in which the young have open eyes, have hair or down, large brains and are immediately mobile and somewhat able to defend themselves against predators. For example, with birds that nest on the ground, such as ducks or turkeys, the young are ready to leave the nest in one or two days. Similarly, butterflies and bees, elephants and horses, monkeys, donkeys and also wilderbeast; they are all able to fend for themselves almost immediately and so they are precocial.
Both altricial and precocial come from the same Latin root as the word "precocious" or "praecox", implying late or early maturity, and "to nourish." It makes reference to the need for extensive parental care required before fledging in altricial species.
Differerent animals employ different precocial or altricial strategies. It hinges on the ability of the female to contribute to the pre-natal and post-natal development of their young. Precocial females are able to provide protein-rich eggs and such their young hatch in the fledgling stage - able to protect themselves from predators (cf. ducks or turkeys) and the females have less involvement post-natal (think turtle eggs). Ostrich eggs are so large, that they are as large as an adult ostrich brain. Altricial females are somewhat less able to contribute nutrients in the pre-natal stage; their eggs are smaller and their young still in need of much attention and protection from predators.
The two strategies result in different brain sizes of the newborns compared to adults. Precocial animals' brains are large at birth relative to their body size, hence their ability to fend for themselves. However, as adults, their brains are not much bigger or more able. Altricial animals' brains are relatively small at birth, thus their need for care and protection, but their brains continue to grow. As adults, altricial animals end up with comparatively larger brains than their precocial counterparts. Thus the altricial species have a wider skill set at maturity.
Humans (and parrots) have developed a strategy comprising both altricial and precocial characteristics. The young are precocial: they have hair/down, eyes are open, and yet are immobile and require great investiture by the parents to protect them from predators and to provide nutrients to raise them to maturation. Humans (and parrots) have relatively large brains at birth, but brain size nonetheless continues to grow substantially to maturity.
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External links
★ The eight recognized modes (or categories) of development, ranging from full precocity to altriciality are discussed in Standford's: Precocial and Altricial at stanford.edu/group/stanfordbirds/text/essays/Precocial_and_Altricial.html. [1]".
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