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Cloaca. A cloaca (/ kloʊˈeɪkə / ⓘ kloh-AY-kə), pl.: cloacae (/ kloʊˈeɪsi / kloh-AY-see or / kloʊˈeɪki / kloh-AY-kee), or vent, is the rear orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles, birds, and a few mammals ...
The anatomy of bird's respiratory system, showing the relationships of the trachea, primary and intra-pulmonary bronchi, the dorso- and ventro-bronchi, with the parabronchi running between the two. The posterior and anterior air sacs are also indicated, but not to scale. Inhalation–exhalation cycle in birds.
Pangalloanserae (fowl) Neoaves. Synonyms. Neornithes Gadow, 1883. Birds are a group of warm-blooded vertebrates constituting the class Aves (/ ˈeɪviːz /), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.
This is the reproductive method used by most animal species, as opposed to viviparous animals that develop the embryos internally and metabolically dependent on the maternal circulation, until the mother gives birth to live juveniles. Ovoviviparity is a special form of oviparity where the eggs are retained inside the mother (but still ...
A diagram of a bird egg. Eggs of various birds, labelled (Trinity College Zoological Museum, Dublin) Bird eggs are laid by the females and range in quantity from one (as in condors) to up to seventeen (the grey partridge). Clutch size may vary latitudinally within a species. Some birds lay eggs even when the eggs have not been fertilized; it is ...
The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. [1] Unlike most organ systems, the sexes of ...
Parthenogenesis (/ ˌpɑːrθɪnoʊˈdʒɛnɪsɪs, - θɪnə -/; [1][2] from the Greek παρθένος, parthénos, 'virgin' + γένεσις, génesis, 'creation' [3]) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means development of an ...
The lake duck holds the Guinness World Record for having the largest avian reproductive organ, from a specimen in Córdoba, Argentina that had a penis measuring 42.5 centimetres (16.7 in). [3] It also has the longest penis of any vertebrate in relation to body length. The penis, which is typically coiled up in flaccid state, can reach about the ...