If you’ve been anywhere near fresh water in the past few
weeks, chances are you’ve come across a frog or two. Here at Preston Montford
they’ve been popping up everywhere as they wake from hibernation and begin
their quest to raise the next generation. As I rescued one unfortunate toad
that had tumbled down a drain outside Caradoc classroom, I couldn’t help but
wonder…what actually is a toad? Is it just a frog with an ugly complexion? How
can I be a biology undergraduate and not even know the difference between a
frog and a toad?
The answer is, like many things in biology (and life), it’s
complicated. Frogs and toads are both amphibians, a class of vertebrates that
usually spend their larval stage in water before metamorphosing into their
air-breathing adult forms. If this isn’t crazy enough, amphibians are also the
owners of some of nature’s most exciting skin, which can act as a secondary respiratory
surface and may secrete predator-deterring toxins. The golden poison frog is
the most poisonous vertebrate in the world, containing enough venom to kill 10
adult men!
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| Phyllobates terribilis, the aptly named golden poison frog. Source: https://upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Schrecklicherpfeilgiftfrosch-01.jpg/786px-Schrecklicherpfeilgiftfrosch-01.jpg |
Within the amphibians, the order Anura, literally translating to “without tail” in Ancient Greek, includes both frogs and toads. This distinguishes them from “tailed” amphibians such as newts and salamanders, but this is about as far as taxonomy takes us. There is a family of “true toads”, (Bufonidae), within this order which are grouped together based on DNA and skeletal characteristics, like their lack of teeth. However, there are several “true toads” that have an appearance more similar to frogs, and many frog species outside this group that most people would distinguish as toads. In short, it’s a massive grey area and you’d be forgiven for just collectively labelling them as frogs, (which would technically be correct).
So is that it? Are toads just frogs with wrinkly skin? Well,
yes, and no. Despite the many similarities between them, there are several
characteristics that are generally recognised as more frog-like or more
toad-like. Frogs tend to have longer legs for jumping between ponds, whereas
toads have shorter legs for walking and hopping on land. Toad spawn is also
distinguishable from frog spawn in that the eggs tend to be laid in long chains
rather than clusters. Some toads such as Nimbaphrynoides
occidentalis don’t even lay eggs at all, but actually give birth to little,
fully formed toadlets, skipping the tadpole stage entirely. As I mentioned
earlier, true toads also do not have any teeth…which means yes, most frogs do.
They’re pretty small though, and are used for gripping onto their prey, not
gnawing on human fingers.
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| Long ribbons of toad spawn. Source: https://i.ytimg.com/vi/aGwAgLHY-78/maxresdefault.jpg |
Of course, it’s impossible to talk about any wild animal
these days, without mentioning how they’re suffering at the hands of humans. Frogs
and toads make up around 90% of the world’s amphibian species, almost half of
which are now in danger of extinction. Habitat loss, climate change and
pollution, as well as the threat of the parasitic fungus known as amphibian
chyrrid means it’s not a great time to be a frog, and quick action is needed if
we are to save these iconic animals. If you have the space in your garden you
may want to consider building a pond. Make sure it has plenty of vegetation and
shallow sides to help the frogs hop in and out. I’ve seen at Preston Montford
that even the smallest ponds can support a wealth of amphibian life, so building
one really does make a difference! Of course we aren’t all able to build ponds
in our gardens, but we all have the power to make an impact, whether that’s by
reducing our carbon footprint or by occasionally rescuing toads from
unfortunate places.
If you want to learn more about frogs and other amphibians,
why not check out our courses at https://www.field-studies-council.org/individuals-and-families/natural-history/animals/reptiles-and-amphibians.aspx?
By Hannah Lawson (Education Assistant).
References
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