Question

how does fertilization occur in frog.???? answer in long but not so long and answer if you are 100 and 10 means 110 percent sure because have exam tomorrow of science.

Answer 1

A more general term for fertilization accomplished outside the female's body, and therefore including amplexus, is external fertilization. Frogs and toads don't have penises. During amplexus the female discharges eggs -- usually into water -- while the male sheds sperms over the eggs.

Answer 2

Hope it helps 

Typically, frogs lay eggs. This process usually occurs through external fertilization, where the female releases her eggs from her body into water. Then, the male releases his sperm to fertilize them.

However, a few species of frog use internal fertilization. In this case, the eggs are fertilized inside the female’s body before they are released. All mammals, including humans, use this process of fertilization.

For many years now, scientists have known about a species of fanged frog, Limnonectes larvaepartus, found in the forests of Sulawesi (an Indonesian island). However, little was known about how this species reproduced.

Inside of the female fanged frog, the researchers found developed tadpoles rather than eggs. Click to enlarge.

Was it through the more common process of external fertilization? Or internal fertilization? Do they lay eggs on leaves or in water, like most frog species? 

In a recent expedition to Indonesia, scientists went out to explore streams and other bodies of water. They searched for these fanged frogs, and caught them with their hands. After catching a number of these frogs, they discovered something unexpected.

Instead of eggs, they found tadpoles inside the frogs. The scientists first noticed this while dissecting, or cutting into, the bodies of dead frogs. They did this to better understand the internal structure of the frogs.

A close-up view of the tadpoles found inside a female fanged frog. Click to enlarge.

The scientists also wanted to study the body tissue and DNA from the frogs to map the frogs' genes. This would help scientists to learn the relationship between this frog species and others.

In the bodies of some female frogs, scientists found fully developed tadpoles. In one instance, a pregnant female gave birth to live tadpoles on the hand of a researcher who caught her. 

These tiny tadpoles were mostly clear in color with spots around their bodies. This finding is very unusual because scientists only expected to find eggs, which are common in most female frogs. 

A One of a Kind Frog

Why does this difference make the fanged frog so special? Well, there are over 6,000 known species of frogs, and this is only one that scientists know of that gives birth to live tadpoles.

Scientists used a map of Indonesia to show the locations of the fanged frogs they found, and how these related to other similar frog species. Click for more detail.

The only frogs that give birth in a similar way come from two African toad genera, Nectophrynoides andNimbaphrynoides, and a now extinct species, Eleutherodactylus jasperi. These species give birth to miniature frogs, called froglets, rather than tadpoles. This makes the reproductive process for the fanged frog unique to any other frog that scientists currently know about.

Scientists discovered that the fanged frog uses internal fertilization. Though internal fertilization is found in other frogs, the other species either lay eggs or give birth to froglets. Discoveries like this are very exciting because it opens a whole new door of possibilities for how frogs reproduce. It also brings up questions about the larger role they have in the ecosystem because of their unique life history.

The Secret Life of Fanged Frogs

For the few frog species that use internal fertilization, the males use an intromittent organ. This is a tail-like structure located at the end of their bodies that they use to transfer sperm into the female.

In general, the intromittent organ allows a male to deliver sperm to the female during internal fertilization. Scientists were puzzled that the male fanged frog did not appear to have this organ. Image by Mokele.

 However, such an organ has not been found in male fanged frogs. This has left scientists puzzled as to how the eggs are fertilized. Unfortunately, no one has seen this fanged frog mate in the wild.

So, how do we know that these frogs use internal fertilization? Simply put, since the scientists saw the frog give birth to live tadpoles, fertilization must have occurred within the frog’s body. Fertilization would need to have occurred so that the tadpoles could develop inside the female frog’s body in the first place.

There is still much to be learned from the fanged frog, such as how females know when to give birth. But then again, there remains much more to be discovered in this strange, bizarre, and amazing world of ours.