The Lizard Log

The Langkilde Lab in Action

Are male wood frogs good midwives?

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This one looks like he might be. Not bad for a deadbeat dad who fertilizes-and-flees.

This spring, I captured wood frog “sex” on video. Since frog eggs are fertilized as they’re being laid, the male wood frog in this video is simultaneously having (his version of) sex and helping to deliver the babies. Wrap your head around that.

Female wood frogs (in this video—the frog that’s underneath) are essentially balloons full of unfertilized eggs when they come to the breeding ponds. When a male finds a female frog, he amplexes her—essentially, he wraps his arms around her from behind, digs in his thumbs, and holds on for dear life. She’ll carry him around for a while like this until she finds the perfect spot in the pond to lay her eggs. At that point, maybe following some trigger that we don’t yet understand, she begins laying eggs.

You’d think that males would just squeeze the eggs out of the females. They’ve got their arms around the female’s balloon-belly, after all. But they also use their shovel-like feet to slowly pull the eggs out of her. Bit by bit, you can see the female’s belly begin to deflate with each male “pull” in this video clip.

In these breeding ponds, there’s fierce competition among males to get a lady. And male wood frogs aren’t too clear on what’s a female, and what isn’t. At 1:50, check out how a lonely male mistakes our busy father for an available lady. It takes the interloper a few moments to realize his mistake… after which he wanders off like nothing out of the ordinary happened.

If you’re in the mood for bad film noir, here’s an alternate version of this video for you to enjoy:

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