Frogs are, in my opinion, some of the most charismatic creatures of the animal kingdom. With their slimy skin, big eyes, long legs and bright colours, they've attracted admiration all around the world. They've inspired fairytale stories and folklore, with characters such as The Wind in the Willows' Mr Toad and the unasumming prince-turned-frog from The Princess and the Frog giving a personality to these wonderful little beings. But some can also be dangerous, with their striking reds, yellows and blacks signifying a toxicity that can be lethal even to humans.
This post looks at some of the most interesting species of frog and where in the world they're found. Reticulated Glass Frogs Hyalinobatrachium valerioi Glass frogs are quite a phenomenon of the natural world. As their name suggests, glass frogs can make themselves appear transparent by hiding 90% of their red blood cells inside their livers. This makes their skin completely transparent so you can actually see their heart beating through their skin. This adaptation, known as 'edge diffusion', allows them to hide from predators whilst they rest on leaves. They are only small and reside in the rainforests of Costa Rica, Panama, Colombia, and Ecuador. When not hiding their blood cells, reticulated glass frogs are identified by their light green colour dotted with yellow spots. They are highly adapted to a rainforest habitat, with strongly webbed toes that allow them to grip onto slippery branches and climb up high into the canopy. They are carnivores, feeding on small insects such as moths and crickets, spiders and even sometimes smaller frogs. After mating, the very territorial male of this species will look after the fertilized eggs laid by the female, staying up night and day to protect his young. He may even mate with several other females during this time, leaving him with a number of egg clutches at different developmental stages. When the eggs hatch, the tadpoles drop into the water below and swim off into the big wide world of the rainforest, to fend for themselves. Unfortunately, like pretty much all frogs, these little creatures are under threat due to human activity, including agriculture, deforestation and human collection.
The underside of a reticulated glass frog - you can see all its organs!
The Wood Frog Lithobates sylvaticus These incredible creatures from North America have worked out a fascinating way to deal with the freezing temperatures they have to cope with. During the winter time, wood frogs seek shelter in leaf litter on the ground and then go on to freeze up to 65% of their body whilst secreting glucose to protect their organs and cells. They stop their breathing, heartbeat and all muscle movements, falling into a long, dormant state. When spring comes round, this process is reversed, as they 'defrost' from their centre outwards, and hop off to start the process of mating. This strange freezing-up technique means that, unlike other frogs who hide far underwater during the winter, these frogs can start mating earlier as the land warms up much faster than ice-covered lakes. They're located mainly in the Northeastern and Alaskan forests of the USA (and are the only frog species that live north of the Arctic Circle) but can also be found in southerly regions such as Alabama and Idaho. They have a distinctive black mark across their face, making them appear as if they're wearing a mask, and come in varying colours of brown, red, green and grey. They are also thought to be one of the few species able to recognize their family; when tadpoles come into contact with one of their siblings, they are likely to stick together. These frogs are preyed upon by snakes, snapping turtles, raccoons, coyotes, foxes and birds, and face an increasing amount of threat from human expansion into their habitat.
A wood frog with the distinctive black mark across its face.
The Kihansi Spray Toad Nectophrynoides asperginis This tiny toad is one of the rarest species on the entire planet and unique in its behaviour too. They are one of the few frog species that give birth to live young instead of frog spawn. They reside in the spray zone of the Kihansi Falls amongst the Udzungwa Mountains of eastern Tanzania. Giving birth to live young helps prevent eggs being washed away by the strong forces of water in their habitat. These toadlets are so tiny that they could fit onto the head of a pin! The kihansi spray toad is extremely vulnerable and did become extinct in the wild for a time. This is thought to have been caused by the construction of a dam on the Kihansi River, which blocked 90% of the water running to the gorge, drastically diminishing the spray conditions and vegetation of the toad's habitat. An outbreak of disease then reduced the population even further. The last 500 were taken into a captive breeding programme (The Kihansi Catchment Conservation and Management Project) which began working to grow their numbers so that they could one day be released into the wild. In 2012, 2,500 frogs were reintroduced into the wild and in 2015, 6,200 individuals were counted, meaning that this programme has been more or less a success! It's one that conservationists look to learn more from as they work to introduce other endangered species back into the wild.
As you can see, the kihansi spray toad is tiny - not even the size of this leaf!
The Surinam Toad Pipa pipa The Surinam toad of South America has one of the most fascinating (and creepy) methods of reproduction. The female Surinam toad has eggs implanted in the skin of her back. After she mates with a male, the eggs slowly sink down into her back and begin developing. The skin grows and swells around the eggs, becoming a honeycomb structure which protects them. After three - four months, the eggs will have developed into little toadlets and will burst through the layer of protective skin on their mother's back. This process ensures that the offspring are protected until they're big and strong enough to fend for themselves. Along with this offbeat reproductive method, they certainly aren't lookers; they're pretty much flattened, with elongated, star-shaped digits and eyes that rest on the tops of their heads looking up into the sky (giving them the romantic nickname 'stargazers'). They live in still water rainforest pools and damp leaf litter in eastern Trinidad and Tobago and the Amazon Basin where they feed on crustaceans, invertebrates and fish, detecting prey with the ends of their long fingertips. You'll be pleased to know, the Surinam Toad is not currently under threat, however human activities such as logging, farming and ranching pose a threat to its habitat and therefore its future survival.
A Surinam toad mother with her offspring emerging from her back.
The Southern Gastric Brooding Frog Rheobatatrachus silus If you thought it was going to get less odd… you were wrong! Instead of carrying her babies in her back, this toad mother swallows her fertilized eggs. All digestive secretions are stopped to prevent her from digesting her own young, but this means she doesn't eat until they jump out of her mouth as tiny frogs about eight weeks later. Along with sacrificing her eating, the female's lungs collapse, meaning she only breathes through her skin throughout her pregnancy. This species is endemic to southeastern Queensland, Australia. However, in a very sad turn of events, the last individual spotted in the wild was in the late seventies or very early eighties and the last individual in captivity passed away in 1983. Scientists are now focusing on this species as one to bring back through the process of cloning. They hope to implant a southern gastric brooding frog's DNA into the embryo of a frog of a similar genetic makeup but so far they haven't got very far. There are both technical and ethical complications when it comes to animal cloning so despite being extinct, this frog species remains on the forefront of scientists' minds.
An old image of a mother giving birth to one of her young.
The Golden Poison Dart Frog Phyllobates terribilis Arguably the most poisonous animal on earth, the toxins produced on this frog's skin mean even touching it could be life-threatening. Just one individual can produce enough poison to kill 10 grown men. The poison works by permanently damaging nerves, stopping them from transmitting electrical impulses, causing heart failure and imminent death within 10 minutes of contact. There is no currently known antidote. It was actually used by the indigenous Emberá people of Colombia on their blowgun darts to hunt for animals, and possibly even further back, in times of battle. This frog is found in lowland rainforests of central and southern America and grow up to just two inches. They have what is called 'aposematic coloration', which simply means they are brightly coloured (in yellows, oranges and greens) as a warning for predators to stay away. They feed on flies, crickets, ants and beetles. The golden poison dart frog's population is threatened by a loss of habitat caused by logging, gold mining and agricultural development. The Ranita Terribilis ProAves Reserve has been set up to combat these issues and works to conserve both this species and its precious habitat.
The poison dart frog is unassumingly deadly.
The Goliath Frog Conraua goliath Growing up to more than a foot in length and weighing as much as a newborn baby, the goliath frog is the largest frog in the world! They're nocturnal and live in the rainforest of western Africa and feed on fish, insects, and crustaceans; but they aren't fussy, even a bat has been found in the stomach of one goliath frog! They're also known as the giant slipper frog and the goliath bullfrog and, fun fact, they can jump up to 10 ft forward! Unlike many of the above species, the goliath frog is not the greatest at parenting; once eggs have been fertilized and laid, the female and male take off, leaving the offspring to develop all alone. Along with being the largest of its kind, they are also one of the oldest, having been on the planet for approximately 250 million years, making them one of the only surviving amphibians that existed before dinosaurs. Unfortunately, this long and fruitful existence is now - you guessed it - under threat thanks to humans. They're currently being illegally poached to be sold as meat or pets, and even transported to the USA for frog-jumping contests. This is a prime example of the exploitative attitude that humans often approach nature with. Along with this, their habitat is being destroyed by agriculture, logging and human settlement. After observing a 50% population decline in the last three generations, the Monte Alen National Park in Equitorial Guinea plus three wildlife sanctuaries in Cameroon are now working to help preserve this species.
Goliath frogs can lift rocks weighing up to 2kg to build their nests.
How You Can Save the Frogs
So, there we have it, an overview of some of the most entertaining and charismatic creatures we have on this precious planet. As you would've gathered from this post, what comes with the stories of many of these species is the very negative impact that humans have on them. It can be disheartening to read about any wildlife because what comes with it is a sense of helplessness and hopelessness. But we can make a change. There are so many people out there trying to reverse the changes that we’ve caused and there's so many ways for us to help from the comfort of our own homes. Froglife, Amphibian and Reptile Conservation and Save the Frogs! are three such charities that focus their efforts on frog conservation, and provide ways for us to help out by donating, volunteering or just spreading the word.
References
Comments