Save the Frogs
Geetha Iyer
Frogs have been around for 300 million years and have survived some very harsh conditions on earth. Yet in their greatest test of survival, they appear to be failing, unable to defend themselves against the changes wrought on this earth by humans and human activities; activities that are destroying the frog’s habitats, changing their environment often so swiftly, that there is isn’t enough time for them to adapt.
Frogs, toads, salamanders, newts, and caecilians are different types of amphibians of which frogs and toads are the ones that are most familiar to us. I wonder how many have seen a caecilian in the wild. The other day, my 27 year-old niece was thrilled to see a tamarind tree for the first time in her life. She studied biology till class 12 and went on to graduate in biotechnology and yet the tamarind tree was new to her. This being so, it is too much to expect to see a caecilian! It is also highly probable that many may have passed it in the forest without a second glance, mistaking it for an earthworm. If you are a fan of PG Wodehouse you have probably been introduced to the newts through his hilarious novels featuring Jeeves and Bertie Wooster. But one doesn’t think like this when one has to study amphibians, do we? Amphibians generally mean, it’s all about frogs, their body parts, physiology, and metamorphosis. There are other ways of learning about frogs. From a perspective that is as important as knowing their physiology and reproduction. It is by looking at their diversity!
Amphibians are among the most endangered group of animals on the planet: nearly one-third of the world’s amphibian species, that is nearly 32 per cent are on the brink of extinction. There are many factors negatively affecting amphibians, which are all due to human activity – habitat destruction, infectious diseases, pollution and pesticides, climate change, invasive species, and over-harvesting for the pet and food trades are some of the reasons for the current status. As the human population spirals out of control, these threats will continue to grow, unless immediate action is taken. Frogs are one of the main indicators of habitat health. If you can’t hear them, be sure that you need to start worrying about the habitat you reside in.
Among the leading amphibian experts in India are Dr. SD Biju and his team from the Dept. of Environmental Studies, University of Delhi. This description on his website www.frogindia.org best highlights the recent discoveries in frog diversity of India – “We have been working on Indian amphibians for over two decades. Till now we have recognized over 100 new species. The first new species was published in 2001. We have formally described 42 new species (another 28 species in press/review), six new genera (three more in press), and one new family (one more in press). We usually put more emphasis on solving long-standing taxonomic issues and describing new species… groups using both morphological traits and molecular evidence.”
India has a rich diversity of frogs and yet there are not many who study them. How diverse are they? The images in this article will give you an idea. But here are a few examples that fascinate me.
The Indian purple frog, also known as the pig-nosed frog, has an unusual look and was discovered in 2003, in the Western Ghats of Kerala. It is an endangered species that spends most of the year underground, using its short, stout limbs like spades to dig as far as 12 feet (3.7 meters) below ground. Thus, the frog’s features which seem so queer to us are adaptations necessary for burrowing deep into the soil where it resides most of the time, coming to the surface only during monsoons to find a mate.
The females are about three times the size of the male and take them on their backs, then hop off to find a spot most suitable to lay eggs, mainly in or near streams.
When the Meowing Night Frog, Nyctibatrachus poocha croaks, it sounds more like a cat than a frog.
The male and female Jog’s Night Frog, Nyctibatrachus jog, have no gender issues. Both males and females look after the eggs.
The Coorg night frog, Nyctibatrachus sanctipalustris, was described 94 years ago by CR Narayan Rao in 1920 after which, when it was thought to be extinct, it has now been rediscovered by Dr. Biju and his team. The species name sanctipalustris in Latin means ‘holy swamp’ a reference to the swampy regions of Coorg where it was rediscovered.
The Wayanad Night Frog, Nyctibatrachus grandis, grows to roughly the size of a baseball. “It’s almost like a monster on the forest floor, a huge animal for a frog, leaping from one rock to another,” says Dr. SD Biju.
So, currently, the known number of frog species from India stands at around 336. According to Dr. Biju, this number indicates probably only half the number of what can be found in the wild and many are waiting to be discovered! He also laments that there are not enough studies in India to find the biological compounds they possess that can be of tremendous significance to science and humanity.
Difficult to believe that the frogs living in dirty waters or slushy dirty soil can have biological compounds that could be of use to humans? Did you know that before modern refrigeration, some people in Russia and Finland preserved milk by placing a live frog in it? This is no joke, but I would not recommend you to try it out without reading more about the species of frogs used or how this could be possible. But there is scientific research in support of this practice.
In 2010, researchers from the United Arab Emirates found more than 100 antibiotic substances in frog skins from around the world. They were different types of peptides, proteinaceous compounds that make up the majority of frogs’ skin secretions, providing a vital defence against bacteria in the wet habitats where frogs live. But some may also be able to protect people, and not just from
rotten milk. One secretion the researchers tested, for instance, could fight the drug-resistant bacteria Ainetobacter baumannii nicknamed Iraqibacter. It is commonly associated with hospital acquired infection. The dry, sandy conditions associated with the conflict zones of Iraq deserts provide an ideal environment for the physiologically robust bacteria to infect the soldiers. ‘Frog skin is an excellent potential source of such antibiotic agents.’
It has been found that skin secretions from three species of Australian frogs (the Green Treefrog Litoria caerulea, the Southern Orange-eyed Treefrog Litoria chloris, and the Green-Eyed Treefrog Litoria genimaculata) have the potential to inhibit HIV, the virus that causes AIDS.
But here is the irony. Frogs in general are known to possess the ability to transmit pathogens such as Salmonella and Mycobacteria to humans. Many also make toxins to repel predators. The Russians and the Finnish people must definitely have taken a calculated risk in using them in their milk. So the frog, Rana temporia that was used to preserve milk was chosen in 2012, by researchers from Russia, Finland and Sweden to find out what special compounds it possessed. Although 21 different antibiotics had already been identified from this species earlier, the research team led by Moscow State University chemist A.T. Lebedev found 76 more compounds and peptides, some of which were better than traditional medicines, at fighting Salmonella and Staphylococcous infections. No surprise then that this practice is seen to exist even today in certain cultures in Europe and Northwestern Asia.
“These peptides could be potentially useful for the prevention of both pathogenic and antibiotic resistant bacterial strains,” the researchers commented “while their action may also explain the traditional experience of rural populations.” We need to exercise caution despite these finds. Many such practices are based on the knowledge these cultures possess and their ability to use the frogs in ways which is not reported. Surely it will not be the case of taking a frog and putting it into the milk! Probably there are many other species of frogs that could render us such services. Scientists over the years have isolated secretions from the frog skin, but have found them to be quite poisonous to human cells or found that the chemicals in our blood could easily destroy some of these peptides, nullifying whatever advantage they could provide us medically.
But if we want frogs to help us, we must first help them. They are disappearing rather fast and we will soon lose a lot of not just medical services but even ecosystem services that frogs render to us. This means that the study of amphibians, frogs should go beyond physiology to ecology.
Frog as an integrated study topic:
I. Start with a frog watch walk. This will give you and your students a first-hand experience of where frogs are. Was it difficult to find a place where you could see them and if it was difficult it would be an eye opener about what we are doing to our habitats. Frogs are bioindicators of a healthy ecosystem. If your frog watch-walk did not result in seeing any frogs then these questions will help you discuss and know more about them:
How do frogs help our environment?
How can we help the frogs?
How many frogs have disappeared?
How does the plight of the frogs impact me?
II. Here are some fun facts about frogs! They are also a starting point to studying about various topics such as food, ears in animals, ecdysis, size, and movement; vocabulary and etymology to discussion on cultures and names.
- Frogs have teeth but toads do not.
- Frogs’ ears are connected to their lungs.
- Frogs shed their skin often to keep it healthy. Once they shed it, they eat it!
- The world’s biggest frog is the Goliath frog from West Africa. It can grow up to 13 inches long and weigh up to 8 pounds.
- The Chinese word for frog is “qing wa.” In Spanish, it is “rana.” In Ethiopia, it’s “enkurarit.” In Tamil, it is ‘thavalai’, while in Malayalam it is ‘thavala’; in Telugu it is ‘kappa’ while in Kannada it is ‘kappe’; in Hindi, it is ‘mendak’, while in Sanskrit it is ‘plavaka’. So how did the English language get the name frog? What is the source of all these names in each of the languages? Discover!
III. Experiments with frogs: These experiments will require to be done in pairs or in groups of three. The teacher needs to ensure that the frogs are not stressed during the experiment. The ability to hold a frog in the hand is in itself an achievement for many students and needs to be appreciated. If a student finds it simply difficult to hold it, she/he must not be forced to do so and can be given other tasks.
This will also require the teacher to get some frogs for observation. It can be done outdoors too. Carrying a simple microscope to the field will not be cumbersome at all.
- These do not require killing a frog. Pick up a frog and hold it gently in your hand. Ask your friend to keep a microscope with a slide with a drop of water on it ready for viewing. Put a drop of water on the slide. Now gently spread the digits of one of the hind legs, place it on the slide and allow your friend to observe under microscope. Red blood cells flowing through the blood vessels can be observed. Make sure that the frog is held gently and not stressed during your experiment.
- Now keep a ruler or an inch tape, a note book, and a pencil ready. Measure the length of hind legs and forelegs and the body distance between the fore and hind legs. Release your frog on the ground and watch it jump. Make a note of how far it jumped and measure the distance it jumped. If you have more than one frog (same or different species) then comparisons can be made, and data analysed and presented as graphs. You can also try imitating a frog leap and compare and contrast and come up with some hypothesis/explanations.
- There are several photos of frogs given in this article. Find the geographic locations, their range distribution, and plot the findings on a map. Research to find out the reasons for their limited or extended ranges.
- Frogs are an integral part of the food web. Explore to find out the ecosystem services they render.
With the kind of environmental degradation one witnesses, the emphasis on studying frogs at middle and secondary school should shift from learning about their interiors to learning about their exterior environment, about their distribution, their absence and the support required to protect them. The biodiversity of frogs in particular and amphibians in general should become an important focus of study in schools.
BOX: Did you know?
The Constitution of India, under Section 51A (G) states, “It shall be the duty of every citizen of India to protect and improve natural environment including forests, lakes, rivers, and wildlife, and to have compassion for all living creatures.” Let us exercise this right for frogs.
Resources
http://kiddyhouse.com/Themes/frogs/ Has information on frogs and some very helpful and interesting diagrams that could make learning about frogs interesting. It also has a template for making masks of frogs.
http://www.frogindia.org/newspecies.htm See the images of all frog species from India discovered recently. A must see site to understand the diversity of frogs found in India.
http://caeciliansofindia.blogspot.in/ An excellent site to learn about Caecilians with image of species seen in India.
http://wgbis.ces.iisc.ernet.in/biodiversity/pubs/ETR/ETR43/ETR43.pdf Useful for a project on frogs, has photographs of some important genera of frogs seen in Karnataka.
http://www.savethefrogs.com An interesting site on frogs of the world.
The author is a consultant for science and environment education. She can be reached at scopsowl@gmail.com.
