Fish in the long-term evolution of the torrent, has evolved a unique set of survival capabilities, including feeding, swimming, etc., and these survival skills are evolved for the sake of reproductive success, so many species in the history of the earth have disappeared, fish are still active in the ocean, fresh water and most of the water. However, different species of fish have evolved special and interesting reproductive strategies and behaviors in response to different environmental conditions.
First of all, the way fish spawn is related to their survival strategy, most of the teleost fish are in vitro fertilization, the amount of eggs is large, most of them are in vitro insemination, but there are also a very small number of virgin reproduction. All cartilaginous fish, such as sharks, rays, stingrays, etc., are in vivo insemination, so their spawning methods are also different. Below, the way in which offspring are produced can be distinguished into oviparous, oviparous and viviparous.
The white lion head of the cichlid family organizes the nest to guard the fertilized eggs.
The difference between oviparous and oviparous?
In oviparous fish, the female will produce mature eggs directly in the water, the male will then release sperm for the eggs and sperm broodstock to be fertilized outside the body, and the fertilized eggs will complete the subsequent embryonic development process outside the body. The way in which oviparous fish reproduce, the fertilization process occurs in the body.
Therefore, comparing the differences in the reproductive characteristics of oviparous and oviparous birth, first of all, in the fertilization mode, oviparous is in vitro fertilization, oviparous birth is in vivo, and all the nutrient sources when the embryo develops after fertilization are from the yolk, and the oviparous birth is also from the yolk. However, for the protection of fertilized eggs, oviparous birth is hatched in vitro, producing eggs to the outside of the body; and oviparous fetus will remain in the body of the broodstock, be fully protected until hatching, and produce juvenile fish with independent living ability, so the vivo fertilized oviparous fish have a handover or a handover foot to transmit sperm to the mother fish, and the fertilized egg will remain in the mother fish after fertilization. Because of this, the space for laying fish to conceive larvae in the reproductive cavity is limited, and the number of eggs fertilized by the sperm strategy used is small, but the survival rate of the oviparous species is better than that of the oviparous species.
Viviparous fish have a mammal-like way of vitro reproduction, and the cycle of embryonic development is exchanged with the mother, so the nutrition required for embryonic development not only depends on the yolk it carries, but also part of the nutrients are supplied from the mother. However, this method of reproduction is only available in some gills of cartilaginous fish, such as the grey star shark, which has been found to have the nutrients needed to grow in the mother's body, through a structure similar to the placenta.
The eggs of the goby snout develop into eye-catching eggs under the protection of the broodstock.
Special egg protection behavior
Although the oochophytic mode of reproduction seems to be less protective of offspring, some oviparous species also have some special egg protection behaviors, for example, cichlid fish will look for appropriate spawning points during reproduction, male fish induce females to enter the spawning house to complete fertilization, broodstock will jointly protect small fish until the small fish are independent, and clownfish will also have egg protection behavior after spawning.
Males of the family Pygmyidae build bubble nests.
The snouted tiger that lives in the stream will choose a suitable stone rock crevice to lay eggs, after laying will guard the fertilized eggs, and always use the pectoral fin to shake the water flow, and pick and remove the undeveloped eggs until the juveniles hatch into juveniles and leave the nest; the covered spotted fighting fish belonging to the labyrinth family, in the reproductive season, will be in the water weeds on the water surface, with the mouth secretion bubbles to build a bubble nest, after building the bubble nest, the male fish begins to chase the female fish for courtship, luring and driving the female fish to the nest, at this time the male will bend the body and hug the female fish, at this time the male will bend the body and hug the female, The female fish at the same time like a prostration spasm in the water to float and sink, the female fish at this time ovulation, the male fish also at the same time, after the egg fertilization, the male fish with the mouth to pick up the eggs and discharge to the nest. After several repetitions and hundreds of eggs, the male fish will begin to guard the fertilized eggs, build a nest, and pick up necrotic and unsupgraded eggs until the small fish hatch.
Male snapper holds fertilized eggs in its mouth.
In the coral reef area, the female lyrefish pairs the selected male ovulation, and the male's mouth is like a "hatchery" that puts the fertilized eggs in the mouth to hatch, and every few minutes it will turn and swallow the fertilized eggs in the mouth, and do not eat for several weeks until the hatched small fish.
Different breeding methods
In addition to the broodstock themselves to protect the juveniles, some fish also have some special breeding behaviors, such as freshwater fish commonly known as cow feces carp high body carp, in the breeding period, the male will have a gorgeous marriage color, the female will also extend a long spawning tube from the cloaca, at this time the male will select the field mussel, began to expel the male, and induce the female to the field mussel to spawn, the female first use the slender spawning tube into the inlet and outlet pipe on the mussel's outer incision membrane, and the eggs are laid on the gill flap of the field mussel. At this time, the male then discharges the sperm into the mussel to fertilize the eggs, and then uses the protection of the mussel to hatch the juvenile fish until the juvenile swims out of the inlet and outlet pipe of the mussel.
Species breed successfully for generations to continue to flourish, and the evolution of fish has produced a variety of breeding strategies and behaviors, which always amazes people and makes the legend of crystal palace amazing everywhere.
Photo: Qiu Yuwen