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Cloaca of a red-tailed hawk. A cloaca (/ k l oʊ ˈ eɪ k ə / ⓘ kloh-AY-kə), pl.: cloacae (/ k l oʊ ˈ eɪ s i / kloh-AY-see or / k l oʊ ˈ eɪ k i / 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.
Parthenogenesis is a mode of asexual reproduction in which offspring are produced by females without the genetic contribution of a male. Among all the sexual vertebrates, the only examples of true parthenogenesis, in which all-female populations reproduce without the involvement of males, are found in squamate reptiles (snakes and lizards). [1]
As such, there are over 80 species of unisex reptiles (mostly lizards but including a single snake species), amphibians and fishes in nature for which males are no longer a part of the reproductive process. [41] A female produces an ovum with a full set (two sets of genes) provided solely by the mother.
The desert grassland whiptail lizard (Aspidoscelis uniparens) is an all-female species of reptiles in North America. It was formerly placed in the genus Cnemidophorus. A common predator of the whiptail lizard is the leopard lizard that preys on A. uniparens by using ambush and stalk hunting tactics. [2] [3] [4] These reptiles reproduce by ...
Females also gain nutrients from sperm storage so the more a female mates with different males the more nutritional access she will obtain. [40] After copulation, some female lizard species chose the sex of their offspring based on the male's sperm. Females produce sons with sperm from larger sires, and daughters from sperm with smaller sires. [41]
They form a ring-like structure for the attachment of genital parts and a pair of lateral clasping organs (claspers, valvae (singular valva), or 'harpes'). The male has a median tubular organ (called aedeagus or phallus) which is extended through an eversible sheath (or 'vesica') to inseminate the female. [ 3 ]
In plants, male reproductive structures include stamens in flowering plants, which produce pollen. [3] Female reproductive structures, such as pistils in flowering plants, produce ovules and receive pollen for fertilization. [4] Mosses, ferns, and some similar plants have gametangia for reproductive organs, which are part of the gametophyte. [5]
The hemipenis is the intromittent organ of Squamata, [4] which is the second largest order of vertebrates with over 9,000 species distributed around the world. They differ from the intromittent organs of most other amniotes such as mammals, archosaurs and turtles that have a single genital tubercle, as squamates have the paired genitalia remaining separate. [5]