Life Finds a Way: Crocodile Impregnates Itself

Jun 9, 2023

A crocodile at a zoo in Costa Rica did something unique. She laid an egg with a baby crocodile inside. That’s not unique, of course. But accomplishing the feat without a father for the egg? That’s a different story.

The baby crocodile didn't live, but it showed scientists something amazing. The mother crocodile had a "virgin birth." This is called parthenogenesis. Scientists found that the baby was almost exactly like its mom, genetically. Usually, babies get half their genes from each parent, but the mother crocodile had never been around any others of its kind — everything that made up the baby came entirely from her.   

This is the first time scientists have seen parthenogenesis in crocodiles. But it's not unusual in other animals. Dr. Warren Booth told the BBC, "We see it in sharks, birds, snakes, and lizards." He added that there were more reports of it happening when people started keeping snakes as pets. "But your average reptile keeper doesn't keep a crocodile.”

Booth is a biologist at Virginia Tech. He studied the American crocodile and her eggs. He published his report this month. He thinks female animals having babies without males could be helpful if only a few animals of a species were left. It might even be how ancient crocodiles survived extinction.  

Booth told the BBC that parthenogenesis happening the same way in different animals suggests it's a very old trait. He added that this supports the idea that dinosaurs could also reproduce this way.

Photo from Reuters. 

Reflect: How might an animal species' ability to reproduce without mating be beneficial to its survival? 

Which of the following ideas is highlighted throughout the story? (Common Core RI.5.3; RI.6.3)
a. The baby crocodile at a zoo in Costa Rica didn't survive.
b. Parthenogenesis has been observed in sharks, birds, snakes, and lizards.
c. Typically, babies get half their genes from each parent.
d. Some animals, like crocodiles, can reproduce without having contact with others of their kind.
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