Fish/ja: Difference between revisions

The primary reproductive organs are paired [[testicle]]s and [[ovary|ovaries]]. Eggs are released from the ovary to the [[oviduct]]s. Over 97% of fish, including salmon and goldfish, are [[oviparous]], meaning that the eggs are shed into the water and develop outside the mother's body. The eggs are usually fertilized outside the mother's body, with the male and female fish shedding their [[gamete]]s into the surrounding water. In a few oviparous fish, such as the [[Skate (fish)|skates]], fertilization is internal: the male uses an [[Ichthyology terms#I|intromittent organ]] to deliver sperm into the female's genital opening of the female. Marine fish release large numbers of small eggs into the open water column. Newly hatched young of oviparous fish are [[Ichthyoplankton|planktonic larvae]]. They have a large [[yolk sac]] and do not resemble juvenile or adult fish. The larval period in oviparous fish is usually only some weeks, and larvae rapidly grow and [[metamorphosis|change in structure]] to become juveniles. During this transition, larvae must switch from their yolk sac to feeding on [[zooplankton]] prey. Some fish such as [[Embiotocidae|surf-perches]], [[Goodeidae|splitfins]], and [[lemon shark]]s are [[viviparous]] or live-bearing, meaning that the mother retains the eggs and nourishes the embryos via a structure analogous to the [[placenta]] to connect the mother's blood supply with the embryo's.