What does It Mean When an Animal is Said to be "Altricial"?
When an animal is altricial, it means that it is born in a helpless state, reliant on its parents for support and protection until it matures. This is in opposition to a precocial animal, an animal which is capable of moving around on its own shortly after birth. Many species of birds are famously altricial, being born naked, blind, and totally helpless, while animals like ungulates tend to be precocial. Altricial animals develop differently from precocial animals, displaying markedly different traits later in life as well as in childhood.
As a general rule, altricial animals are born to parents who might have difficulty defending themselves in the late stages of pregnancy or nesting, making it imperative for the young to be born as quickly as possible. The mothers may also be incapable of providing needed nutrition to the young while they develop. In the case of birds, for example, the mother bird may not be able to build enough egg yolk for the young to develop more fully in the egg.
When an altricial animal is born, it is often blind, and it may lack the plumage or fur associated with adults of the species. Altricial animals also tend to be helpless, unable to move around like mature adults and dependent on others for support, food, shelter, and companionship. Many marsupials, for example, are born naked or blind; baby kangaroos are perhaps one of the more outstanding examples of an altricial animal, as they are born in a form which borders on embryonic. Humans are also altricial, with an extremely long period of development required before they reach maturity.
The parents must therefore have a protected area for their young, and may also have to actively work to protect the babies. Mother rats, for example, are quite ferocious when threatened, and songbirds may use a variety of tricks to distract predators in the hopes of saving their nestlings. One big advantage to being born in altricial state is that the animal's brain will continue to develop and grow for years after birth, allowing altricial animals to learn more and develop wider skill sets than their precocial counterparts.
There are various degrees along the scale when it comes to being born altricial. While some animals demonstrate extreme degrees of altricial or precocious traits, most fall somewhere in the middle. For example, chicks and ducklings are capable of moving around within a few hours of hatching, and they are born with their eyes open, but they are clearly dependent on their parents for warmth and shelter.
In a way, therefore, human beings are also Altricial, right? --NKD
Kittens and puppies are born like this. There are few more dedicated mothers than a mother cat. She has to carry her babies everywhere and they are blind and practically naked until they are older. They can't even urinate without their mother's help, which is why if you find very young, abandoned kittens, you should take them first to a vet. Looking after very young kittens is much more involved than most people think, because they are so helpless. It can be done, but you should find out how to do it first, or you might hurt the babies by mistake.
There are some kinds of frogs and spiders that will carry their babies around for a few weeks until they have developed enough to live on their own. I know the frogs, in particular, do this because they are not water frogs, and don't lay eggs in the water, so there is nowhere for the tadpoles to swim and be independent. If they didn't carry their children around until they developed legs, they would die.
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