altricity

…For example, even though they are both rodents, mice are born hairless and with their eyes closed, while guinea pigs are born with their eyes open and fully furred. A baby that is able to survive on its own immediately after birth is called precocity, while a baby that needs long-term parental protection is called altricity. In general, herbivores tend to be precocial, while carnivores tend to be altricial. In mammals, contraction of the smooth muscle that forms the wall of the uterus often causes the membrane surrounding the fetus to rupture, and the fetus passes through the vagina and is pushed out of the body through the vaginal opening. …

*Some of the terminology explanations that mention "altricity" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…例えば同じ齧歯（げつし）類でも，ネズミの子は無毛で目を閉じたままで生まれるが，モルモットでは開眼で，毛が生えそろった状態で生まれてくる。子が生まれてからすぐに自活能力をもつものを早成性precocity，長く親の保護を必要とするものを晩成性altricityというが，一般に草食獣は早成性，肉食獣は晩成性の傾向がある。哺乳類では，子宮の壁を形成している平滑筋の収縮により，胎児を包んでいる胎膜が破れ，胎児が腟を通り腟口から体外に押し出されることが多い。…

※「altricity」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報