There are many types of fish, some of which reproduce without physical contact. Others, such as rays and sharks, prefer internal fertilization.
For example, a male Phallostethus cuulong uses a priapium to attach to a female’s urogenital opening and fertilize it internally.
Hermaphrodites
Hermaphrodites are animals that possess both male and female reproductive organs at the same time. They reproduce in pairs through multiple matings in which each contributes sperm and eggs. These fishes are rare and have only been observed in a few species of Kryptolebias. Hermaphroditism is an interesting phenomenon, and the observations of “hermaphrodites” in other animals have inspired scientists for decades.
The reproductive behavior of hermaphrodites hasn’t been fully understood, but many species appear to have a sexual relationship with other species. Studies of synchronous hermaphrodites have shown that they rarely self-fertilize and engage in a role-playing relationship between the male and female during the spawning process. This is an evolutionary advantage of hermaphrodite fishes, as this means that the fishes can avoid incompatibility concerns with other species.
Dioecious fish
Most fish are dioecious, meaning they have a male and female reproductive organ. Some species have both sets of reproductive organs, while others have only one. Dioecious fish have sex organs that are located at the back of their anal fins. Sperm is released from these organs and fertilizes an egg. This fertilization process results in the development of the fry embryo.
Plants are also dioecious, which means that they produce both male and female gametes in separate plants. In addition, many dioecious species produce both male and female sperms and eggs. Inbreeding between dioecious species results in less genetic variation and increased heterozygosity.
Ovoviviparous reproducers
The reproductive mode of ovoviviparous species is complex. Some reproduce by retaining ova and not producing offspring, whereas others do so by producing offspring and producing sperm. In either case, they produce free-living, autonomous offspring. The reproductive mode of ovoviviparous species also differs in egg-laying patterns, with a single species depositing fewer eggs than the other.
Most mammals, reptiles, and insects are oviparous. These animals lay eggs within the mother’s body and nurture them until hatching. These animals are mostly found in aquatic environments. In addition, some species, such as the echidna, care for their young until they are old enough to reproduce.
Priapium fishes
It is not known if Priapium fishes have sperm in their heads, but we do know that they have a bony structure called a priapium that the male inserts into the female’s urogenital opening. Priapium fishes have a unique sexual arrangement compared to other species of fish. Males tend to have a priapium on one side of their heads, while females have one on the other side of their heads.
A male fish’s penis (or priapium) is an elaborate, muscular organ, with a urogential opening and a bony rod and sawlike hook. The female’s genital opening is located at the throat, but in some species, it is a different structure. The priapium and the ctenactinium are believed to help hold onto the female during spawning.
Egg scatterers
When egg scattering fish are ready for spawning, their bellies will be rounded. The male will then chase the female around and fertilize the eggs as they are laid. This process can take several hours, and the fish will then resume their normal activity. In general, most fish eat their own eggs after spawning.
Fortunately, many species of fish can produce a small number of offspring. These species are commonly bred as livebearers. Their eggs are laid in the female’s gills, and the young ones will emerge approximately four weeks later. Typically, livebearers will produce 50 to 100 young. Proper feeding can reduce mortality and increase survival rates for these fish.
Egg buriers
Livebearers are fish with a unique way of fertilizing and growing their young. They lay their eggs in a shallow, covered area, and the male fertilizes the eggs by swimming through a spray of semen and diving into the substrate. This process is simple, and these fish are very easy to breed. Their eggs can survive drought conditions, and they can hatch months after laying them. The lifespan of their young is between 50 and 100 days, so proper feeding can increase survival rates.