Search results
Results From The WOW.Com Content Network
Oviparous fish are fish that reproduce by spawning fertilized eggs outside of the body that grow into hatchlings.This process is unlike live-bearing viviparous species, which develop and nourish embryos and inside the womb, or live-beaering ovovivipary species, which develop and nourish eggs with egg yolk.
In oviparous fish, internal fertilisation requires the male to use some sort of intromittent organ to deliver sperm into the genital opening of the female. Examples include the oviparous sharks, such as the horn shark, and oviparous rays, such as skates. In these cases, the male is equipped with a pair of modified pelvic fins known as claspers.
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 the egg by the reproductive system of the mother (the vitellogenesis ).
Ovoviviparous fish give birth to live young. Unlike viviparous species, their embryos are nourished by an egg yolk, and not directly by the parent. See also: Category:Viviparous fish - fish which give birth to live young which receive nourishment whilst in the womb.
Viviparous fish are fish that give birth to live young, the eggs develop whilst receiving nutrition from the parent. See also: Category:Ovoviviparous fish - fish which give birth to live young which do not receive nourishment from the parent whilst in the womb.
Some fish are hermaphrodites, having both testes and ovaries either at different phases in their life cycle or, as in hamlets, have them simultaneously. Over 97% of all known fish are oviparous, [74] that is, the eggs develop outside the mother's body. Examples of oviparous fish include salmon, goldfish, cichlids, tuna, and eels.
Among mammals, the monotremes are oviparous. Ovo-viviparity: or oviparity with retention of zygotes in either the female's or in the male's body, but there are no trophic interactions between zygote and parents. [1] This mode is found in the slowworm, Anguis fragilis. In the sea horse, zygotes are retained in the male's ventral "marsupium".
Zenarchopteridae, the viviparous halfbeaks, is a family of ray-finned fishes in the order Beloniformes.The Zenarchopteridae exhibit strong sexual dimorphism, practicing internal fertilisation, and in some cases ovoviviparous or viviparous (the family also includes oviparous species).