Australian Museum Herpetology Department

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Frequently asked questions

Frogs

How many species of frog are there in the world?

Scientists have now described about 4740 species of frogs world-wide.

How many species of frogs are native to Australia?

There are now about 216 species of frogs native to Australia.

How many species of frogs have been introduced to Australia?

There is only one introduced species of frog in Australia - the Cane Toad, Bufo marinus.

How many Australian frogs live in the desert? How do they survive?

Only about 15 species of frogs (about seven percent of the total) live exclusively in the Australian arid zones. Perhaps five additional species penetrate the area regions from the wetter parts of the continent.

Arid zone frogs have two main ways of surviving the long periods of dry weather and the high temperatures of these areas. Some species burrow deep underground while many move into deep crevices. And some of the burrowing species store large amounts of water in their body before they burrow.

What is the most endangered species of frog in the world?

To answer that you have to think about what endangered means. Is it the frog species with the smallest number of individuals? Or is it the frog species in which the number of individuals is being reduced the most quickly? Either way you ask the question, for most species we don't have the numbers to actually say which is the most endangered. But we do know that many kinds of frogs have been reduced to a very small number of individuals and many frogs have numbers which appear to be declining rapidly. For example, the Ramsey Canyon Leopard Frog Rana subaquavocalis in the United States is known from only about 100 individuals and Hamilton 's Frog Leiopelmahamiltoni from a small island in New Zealand appears to consist of only about 300 individuals.

In general, the more restricted a species habitat is, the more endangered it is likely to be. That is why is so important to save habitats and not just keep rare frogs breeding in zoos.

What is the most common frog in the Sydney area?

In the Sydney region, the two most common frogs are probably the Striped Marsh Frog, Limnodynastes peronii and the Eastern Toadlet, Crinia signifera.

What is the smallest frog in the world?

Two frogs are the smallest frogs in the world. Eleutherodactylus iberia (no common name) from Cuba and the Gold Frog Psyllophryne didactyla from Brazil which measures only about 10 mm from the tip of the snout to the tail end.

However, many small species of frogs are not known from many individuals and it is always possible that another only poorly known species might turn out to be the smallest. How many people would it take to discover the smallest person?

How long do frogs live?

The life span of frogs, like lizards, varies depending on the species. But in general, the larger the species of the frog, the longer it is likely to live. Some small frogs live on average for just one year, whereas some large frogs live for many years before they croak.

Do frogs have five senses like humans?

Yes, but their sense of smell may not be as good as ours.

Do frogs change colour?

Frogs have the capacity to change colour both as tadpoles and as adults. In most species, both the tadpoles and the frogs can turn darker and paler, depending on things like the surrounding temperature and whether they are frightened or not.

Frogs also have a different colour pattern when they are tadpoles and when they are frogs. Most tadpoles are a fairly uniform and drab colour, but frogs often have distinct patterns and have some bright colours somewhere on the body.

Can some frogs change skin colour as a form of camouflage?

Most frogs have their camouflage colours "built in" permanently. Colour change in frogs usually have to do with the frogs temperature and perhaps whether it is stressed or not.

Do frogs react to changes in light intensity?

All frogs would react to changes in light intensity. They might react by moving toward or away from the light, or by changing their skin colour, that is, becoming paler or darker.

Why do some frogs have suction pads or discs for climbing?

First, the pads don't work by suction, that is, by creating a vacuum between them and whatever the frog is climbing on. Instead the toe pads work by friction.

And for those frogs with toe pads and which climb, there are benefits to be gained by being able to get up off the ground. Climbing frogs may be able to find kinds of food that ground frogs can't, and climbing frogs can flee to places where ground frogs can't.

Do frogs sweat?

Frogs don't have sweat glands. However, their skins are always moist and the evaporation of this moisture helps keep them cool.

Why are frog’s eggs clear?

Actually, the clear part is the protective "jelly" that surrounds the actual egg which is usually dark on top and pale on the bottom. The egg lies at the centre of the jelly capsule and is usually dark on one half and pale on the other. The dark part is where the little tadpole forms.

How big can a frog inflate its throat?

Some frogs can actually inflate the throat to larger than the size of the head. And it is only male frogs that inflate the throat. It is only the males that call, and the inflated throat helps to make the sound louder.

How do frogs jump so well?

Frogs are good jumpers because they have relatively long rear legs and short bodies and lack tails. The legs give them power to jump, the short body helps them withstand the impact of landing, and there is no tail to get in the way or add unnecessary weight.

What do frogs eat?

All frogs eat other animals. None eat plants. Frogs usually eat insects and other arthropods. But some frogs will eat animals with backbones, such as other frogs, lizards and small mammals. A few frogs even eat bats which they catch from the water, when the bats fly low to drink.

How long do frogs care for their young?

In only a few frogs do either the mother or the father look after the eggs and sometimes the tadpoles. In no species do both parents look after the eggs or tadpoles together.

Some frogs just guard the eggs but other frogs may look after both the eggs and the tadpoles. For example, the male Pocket Frog from Australia, Assa darlingtoni, guards the eggs on land until they hatch and then carries the tadpoles in two pouches along his back until they transform into little frogs.

How do frogs develop from a tadpole? How does the tail disappear?

Many animals go through big changes as they develop and grow. It is almost as if they were several kinds of animals one after another. Among animals with backbones, only some fish and frogs go through such big changes.

In the transition from tadpole to frog, some body parts are broken down into small molecules and reused to build new body parts. For example, the tail is lost but legs are grown.

The changes from a tadpole to a frog occur when one set of genes (call them the tadpole genes) are turned off and a new set of genes (the frog genes) are turned on. All the genes are present in the individual fertilised egg, but some just lie quietly waiting their turn to play their role in the total life span of a frog.

You also have genes in you that have yet to be turned on and to help you become adults.

How do frogs avoid predators?

One of the most common ways of avoiding trouble when danger threatens is just to remain very still and hope that the predator doesn't see you.

But if this doesn't work and the predator gets closer, then most frogs jump to safety. An ability to jump long distances, is one of the most distinctive things about frogs. How many times the length of your body can you jump? How many can a frog jump?

If a frog is caught by a predator, some species may make a loud noise, and most have things in the skin that may make them taste bad.

Are all frogs poisonous?

All frogs have many glands in the skin and these glands produced many different compounds which cover the skin. Many of these compounds have evolved to deter a whole range of organisms that might infect the skin of frogs, such as bacteria, fungi and other microbes or that might eat the whole frog, such as snakes. Therefore, it seems likely that these compounds might also be generally toxic to other animals that would not ordinarily bother frogs such as humans. [Maybe that's why you never see smart people walking around with a frog in their mouth].

Which frog is the most poisonous?

This is difficult to answer because not many people ever die by coming into contact with frogs. However, we do know that many frogs have powerful toxins in their skins, and these toxins can range from mildly irritating to eyes and skin to deadly if swallowed.

Cane Toads, Bufo marinus, are known to be deadly to humans, and the skin secretions of arrow-poison frogs of tropical American are used to tip the hunting arrows of the indigenous people.

What colours are poisonous frogs?

Like many really deadly poisonous animals, poisonous frogs often have very bright and conspicuous colour patterns generally made up of reds, oranges, yellows and blues. These kinds of bright colours and patterns say: "You had better not eat me, because remember how bad something as colourful as me tasted last time you tried?"

Are frogs and lizards related?

All living things are related. It is just a matter of how close or distant the relationship is. On this basis, you can say that frogs and lizards are only distantly related. Other living organisms that are more closely related to frogs are salamanders (but none of these are in Australia ). Other living organisms more closely related to lizards are, in order of a increasingly distance of relationship: snakes, the tuataras in New Zealand, crocodilians and birds, and mammals.

How did frogs evolve?

Frogs evolved from ancestors that looked like living salamanders which themselves look like lizards with smooth moist skins instead of dry scaly skins. Frogs probably evolved in the Triassic, more than 200 million years ago.

The first fossil that everyone agrees is almost certainly a frog is Triadobatrachus from the Lower Triassic in Madagascar. The Lower Triassic was approximately 240 to 245 million years ago.

But imagine how difficult it is to identify the "first" of any kind of plant or animal. You need a fossil that shows the critical feature of that group of animals. What part of a frog do you think you would need to tell that it was a frog. One tooth? One toe bone? A leg bone?


Copyright © Australian Museum, 2002



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