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Frog Reproduction

It’s almost Valentine’s Day and I know all of you are wondering, how do frogs have sex? Today is your lucky day because I’ll be explaining it. There are many different ways that frogs and toads reproduce and if I try to cover them all, this post might become its own book.

Frogs and toads generally start breeding in early spring or late winter if the weather is nice. They also start breeding at the change from dry season to wet season. The breeding season ends in summer, giving the offspring the longest time to develop before winter or dry season comes.

Bufo_bufo_couple_during_migration(2005).jpg
By Janekpfeifer at de.wikipedia – Uploaded by Janek, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=251993

The most well known way that frogs reproduce is in the water through external fertilization. Male frogs can be found in bodies of water calling for female mates during the night. Some frogs breed in vernal ponds / ephemeral pools (temporary ponds created by melting of snow and spring rain) because these ponds lack fish that can prey on their offspring. Other frogs look for more permanent bodies of water because their tadpoles don’t undergo metamorphosis until after the next winter. For this sort of reproduction, females come into the territory of a male and the male jumps on her back. This mating position is called amplexus. Males will often try to mate with anything, including different species of frogs, toads, and fish. Male frogs don’t have penises, they have an opening called the cloaca where the sperm is released. Females have this opening too, where the eggs come out. The male grips the female from behind so that when he releases his sperm, there’s a better chance at fertilizing the eggs. Other males sometimes will come into the frog’s territory and also jump on the female while the other male is holding her. They sometimes even form giant piles of frogs or toads. Occasionally, it gets so rough, the female is killed. Usually though, the female releases her eggs and the male fertilizes them and she goes on her merry way.

While some frogs mate in the water like that, many others mate on the ground, and some even mate in the trees. During reproduction in the trees, the couple makes a foam nest out of the eggs and other secretions to keep the eggs dry. For the species that reproduce on land, the eggs might never need water because when they hatch, the offspring is immediately a froglet and not a tadpole.

Ascaphus_truei_web
By Mokele – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11586685

Not all frogs use external fertilization, some use internal fertilization. There are different ways that frogs and toads use internal fertilization. Some frogs such as the Tailed Frogs from Ascaphidae, perform internal fertilization then lay fertilized eggs later. The Tailed Frog’s tail is used in fertilization.

The Nimba Toad (Nimbaphrynoides occidentalis) is the only known viviparous frog / toad. The frog is pregnant for 9 months and the babies feed off the mom’s secretion.

The genus Nectophrynoides and the Golden Coquí (Eleutherodactylus jasperi) are the only known ovoviviparous frogs and toads, where they have eggs inside them that hatch and then they give birth to little froglets.

Limnonectes_larvaepartus_adult_female
Photo By Mirza D. Kusrini, Jodi J. L. Rowley, Luna R. Khairunnisa, Glenn M. Shea, Ronald Altig – Kusrini MD, Rowley JJL, Khairunnisa LR, Shea GM, Altig R (2015) The Reproductive Biology and Larvae of the First Tadpole-Bearing Frog, Limnonectes larvaepartus. PLoS ONE 10(1): e116154. doi:10.1371/journal.pone.0116154, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=37784743

Ok just kidding about them being the only ovoviviparous frogs because there is another one but it’s kind of different. The Fanged Frog (Limnonectes larvaepartus) is also ovoviviparous but instead of giving birth to froglets, it gives birth to tadpoles.

 

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