Are there male animals that give start or lay eggs? | Scientists reply | Science | EUROtoday

Most species have what we name sexual dimorphism, which is the physiological distinction between females and males. This distinction impacts, amongst different points, the reproductive system. That of the females is the one that’s ready to provide start or lay eggs and that of the males to fertilize the oocytes. This signifies that males can’t give start or lay eggs as a result of their organisms wouldn’t have the required organs to take action. What does occur in some species is that males are far more concerned in replica than the mere fertilization of females. Two clear examples are these of seahorses and a few species of fish.

In the case of seahorses, what occurs is that the females switch the eggs to an incubator bag carried by the males and in that bag, first the male fertilizes them internally after which incubates them, that’s, retains them secure to permit the embryos to develop.

Once the eggs have developed and the younger are able to hatch, it’s the males who expel the eggs. And they do it via contractions just like these of childbirth, even of their our bodies hormones are launched which can be similar to these launched within the our bodies of females throughout being pregnant. Pipefish have a system similar to that of seahorses for the fertilization and incubation of their eggs. In another species of fish what occurs is that the males maintain the eggs of their mouths till they hatch.

There are additionally circumstances of incubation of eggs by males in some species of birds. For instance, within the case of the emperor penguin, it’s the males that incubate the one egg that the females deposit in every clutch. Surely you’ve gotten seen pictures or illustrations exhibiting how these animals maintain the egg heat between their paws whereas the feminine brings them meals. In the case of rheas, that are South American birds just like ostriches, it’s the males that construct a nest during which the females lay the eggs. But each the incubation and the care of the younger as soon as the eggs hatch and till roughly six months later are carried out solely by the males who’re additionally, just like the females of many species, particularly aggressive in the direction of different animals that strategy the eggs or the younger.

There are numerous evolutionary explanations for this truth, which, as I’ve defined, does exist in nature, though it isn’t frequent. The most accepted of those evolutionary explanations is that any such shared parenting has an evident decrease power price for females. As quickly because the females have gotten rid of the eggs, since they don’t have to incubate them, they’re prepared once more to put extra eggs, so the survival of the species has a higher likelihood of success, since will probably be in a position to enhance the variety of offspring.

There is one other facet which will even have an evolutionary rationalization. In these circumstances of fertilization inside the male’s personal physique, they be certain that the offspring shall be his descendants.

But what I’m explaining to you can not happen in mammals as a result of, as I informed you initially, mammals have sexual dimorphism: the reproductive techniques of females and males are completely different and have completely different features. Males lack constructions equivalent to ovaries, fallopian tubes, uterus or start canal, vital for gestation and giving start.

Ana Josefa Soler Valls She is a professor of Animal Production on the University of Castilla-La Mancha, director of the Higher Technical School of Agronomic and Forest Engineering and Biotechnology and an professional in animal replica.

Coordination and writing:Victoria Toro.

Question despatched through e-mail byPaula García Pásaro.

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