FEROCIOUS ANIMALS

Record-breaking crocodile: first female to lay eggs without fertilization

Nature never ceases to amaze us with its extraordinary displays of adaptation and survival. In a Costa Rican zoo, an unprecedented event took place in January 2018: a female crocodile laid a brood of eggs despite living alone for a good 16 years. 

What makes this story even more incredible is that some of these eggs developed without any fertilisation by a male. 

In this photogallery, we explore the extraordinary phenomenon of parthenogenesis in the crocodile kingdom, shedding light on the significance of this event and opening up new perspectives on the evolution and reproduction of reptilian animals.

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A record-breaking female crocodile
Nature never ceases to amaze us with its extraordinary displays of adaptation and survival. In a Costa Rican zoo, an unprecedented event took place in January 2018: a female crocodile laid a brood of eggs despite living alone for a good 16 years. What makes this story even more incredible is that some of these eggs developed without any fertilisation by a male. In this article, we explore the extraordinary phenomenon of parthenogenesis in the crocodilian kingdom, shedding light on the significance of this event and opening up new perspectives on the evolution and reproduction of reptilian animals.
Getty Images (generic image)
An exceptional event
In January 2018, a zoo in Costa Rica witnessed an exceptional event. A female crocodile, who had been living alone for a good 16 years, laid a brood of eggs. What made this situation extraordinary was the fact that some of these eggs seemed to be able to develop, despite the fact that the female had had no contact with a male. This event attracted the attention of researchers from different parts of the world.
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The first time
An article published in the journal 'Biology Letters' reported the surprising discovery that one of the crocodile pups, born from these eggs, was a parthenogen. Parthenogenesis is a virgin birth phenomenon, in which the individual contains only the genetic material of its mother. This is the first time parthenogenesis has been observed in crocodiles, although it has been identified in other creatures such as the king cobra, the sawfish and the California condor. This discovery opens up new possibilities for studying the evolution of reproduction in reptiles.
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Parthenogenesis
Virgin birth occurs when an egg cell inside the mother's body divides repeatedly, generating an individual with exactly half the necessary genes. During this process, three smaller cell sacs, called polar bodies, are produced, which usually degrade. However, in vertebrates capable of parthenogenesis, a polar body can fuse with the egg, creating a cell with the right complement of chromosomes to form an individual. This seems to be the case with the crocodile in question, as stated by Warren Booth, entomologist and associate professor at Virginia Tech.
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The reasons for parthenogenesis
The reasons for parthenogenesis. The survival of individuals born through parthenogenesis may be compromised compared to those born through sexual reproduction. However, thanks to the increasing ease of DNA analysis, it has been discovered that parthenogenesis is not as rare as originally thought. This phenomenon could provide a species with the ability to survive in prolonged periods when no sexual partner is available. A parthenogenetic individual, carrying largely the same genes as its parent, could live long enough to await the arrival of a mate, thus enabling sexual reproduction, which tends to produce more vigorous offspring.
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