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Oviparity occurs in all birds, most reptiles, some fishes, and most arthropods. Among mammals , monotremes (four species of echidna , and the platypus ) are uniquely oviparous. In all but special cases of both ovuliparity and oviparity, the overwhelming source of nourishment for the embryo is the nutrients stored in the yolk, pre-deposited in ...
External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. [1] It is contrasted with internal fertilization , in which sperm are introduced via insemination and then combine with an egg inside the body of a female organism.
Fertilization is the fusion of gametes to produce a new organism. In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization.
Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semiaquatic life in a marine environment. Only about 100 of the 12,000 extant reptile species and subspecies are classed as marine reptiles, including marine iguanas , sea snakes , sea turtles and saltwater crocodiles .
Reptiles, from Nouveau Larousse Illustré, 1897–1904, notice the inclusion of amphibians (below the crocodiles). In the 13th century, the category of reptile was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, lizards, assorted amphibians, and worms", as recorded by Beauvais in his Mirror of Nature. [7]
The young of ovoviviparous amphibians are sometimes born as larvae, and undergo metamorphosis outside the body of the mother. Modes of reproduction include [3] based on relations between zygote and parents: Ovuliparity: external fertilisation, as in arthropods, many bony fishes, and most amphibians
While reptiles and amphibians can be quite similar externally, the French zoologist Pierre André Latreille recognized the large physiological differences at the beginning of the 19th century and split the herptiles into two classes, giving the four familiar classes of tetrapods: amphibians, reptiles, birds and mammals.
Biology of the Reptilia is an online copy of the full text of a 22-volume 13,000-page summary of the state of research of reptiles. HerpMapper is a database of reptile and amphibian sightings; Amphibian and Reptile Atlas of Peninsular California, San Diego Natural History Museum; A Primer on Reptiles and Amphibians; Field Herp Forum