In Biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. Foundations of modern biology There are five unifying principles The opposite developmental strategy is called "altricial", where the young are born helpless. Altricial means "requiring nourishment" and refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or Extremely precocial species may be called "superprecocial". The term superprecocial refers to a level of physical maturity and capability in young animals that is most extreme These three categories form a continuum, without distinct gaps between them. Precocial species are normally nidifugous, meaning that they leave the nest shortly after birth. An animal that leaves its nest shortly after birth is said to be nidifugous.
The span between precocial and altricial species is particularly broad in birds. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. Precocial birds, including many ground-nesting species, have offspring that are born with well-ossified skeletons, with good sight, and covered with feathers. Very precocial birds can be ready to leave the nest in a short period of time following hatching (e. g. 24 hours). Many precocial chicks are not independent in thermoregulation (the ability to regulate their own body temperatures), and they depend on the attending parent(s) to brood them with body heat for a short period of time. Thermoregulation is the ability of an Organism to keep its body temperature within certain boundaries even when temperature surrounding is very different Precocial birds find their own food, sometimes with help or instruction from the parents. Examples of precocial birds include the domestic chicken, many species of ducks and geese, and rails and crakes. The chicken ( Gallus gallus, sometimes G gallus domesticus) is a domesticated Fowl which is traditionally believed to have descended from For duck as a food see Duck (food; for other meanings see Duck (disambiguation. Goose (plural geese) is the English name for a considerable number of Birds belonging to the family Anatidae. The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized Birds The family exhibits considerable diversity The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized Birds The family exhibits considerable diversity The most extreme, superprecocial birds are the megapodes, where the newly-hatched chicks dig themselves out of the nest mound without parental assistance, and fly on the first day after hatching. The term superprecocial refers to a level of physical maturity and capability in young animals that is most extreme The megapodes, also known as incubator birds or mound-builders, are stocky medium-large chicken-like Birds with small heads and large feet in the family
Precociality is also found in many other animal groups. Familiar examples of precocial mammals are most ungulates, the guinea pig, and most species of hare. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands Ungulates (meaning roughly "being Hoofed quot or "hoofed animal" are several groups of Mammals most of which use the tips of their toes usually The Guinea pig (also commonly called the cavy after its scientific name Cavia porcellus) is a species of Rodent belonging to the family Caviidae Hares and jackrabbits are Leporids belonging to the Genus Lepus. This last example demonstrates that precociality is not a particularly conservative characteristic, in the evolutionary sense, since the closely related rabbit is highly altricial. Rabbits are small Mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world Altricial means "requiring nourishment" and refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or
Precocial species typically have a longer gestation or incubation period than related altricial species, and smaller litters or clutches, since each offspring has to be brought to a relatively advanced (and large) state before birth or hatching. Gestation is the carrying of an Embryo or Fetus inside a Female Viviparous Animal. Incubation is the process by which Birds hatch their eggs, and to the development of the Embryo within the egg
The phenomenon of imprinting studied by Konrad Lorenz is characteristic of precocial birds. This article is about the psychological term For other meanings see Imprinting. Konrad Zacharias Lorenz ( November 7, 1903 in Vienna &ndash February 27, 1989 in Vienna) was an Austrian
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Etymology
The word "precocial" is derived from the same root as precocious, implying in both cases early maturity. [1]
Phylogeny
Precociality is thought to be ancestral in birds. Thus, altricial birds tend to be found in the most derived groups. There is some evidence for precociality in Protobirds (Elzanowski, 1995. " Protobird " is an informal term that has been used by some Paleontologists when discussing animals that while technically classified as non-avian Dinosaurs ) and Troodontids (Varricchio et al. Troodontidae is a family of Bird -like theropod Dinosaurs In previous decades troodontid fossils were few and scrappy and they have therefore 2002).
References
Footnotes
- ^ Webster's New World Dictionary. David B. Guralnik, Editor in Chief. New York:Simon and Schuster, 1984. Simon & Schuster Inc, a division of CBS Corporation, is a Publisher founded in New York in 1924 by Richard L
Notations
- Starck J. M. , Ricklefs R. E. Patterns of Development: The Altricial - Precocial Spectrum. In; Avian Growth and Development. Oxford University Press, New York, NY, 1998.
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