Glass frogs are an unusual group of frogs with unique characteristics. Found in rainforests in Central and South America, their name is derived from their skin, which is transparent in some areas of their body. Keep reading to learn 15 interesting facts about the delicate little glass frog and how it is adapted for life in the rainforest.
1. The Underside of Their Body is Translucent
Glass frogs are usually some shade of green in color, ranging from dark olive to bright, vibrant green. This green coloration is on the top of their body, on their back and the backs of their arms and legs. Green allows them to camouflage with the many green leaves of the rainforest.
When you see the underside of a glass frog, you can see how it earned its name. The skin on the underside of their body is translucent. You can see right through the skin, and view the bones and organ inside their body.
2. They Have Sticky Toes
Glass frogs are adept tree climbers, with sticky toe pads that help them grip a variety of surfaces like leaves and tree bark. Their toes have soft, rounded pads that create friction for clinging to surfaces, aided by mucus secretions that improve adhesion and keep their pads clean.
3. They Are Arboreal Frogs
Speaking of climbing with sticky toes, this is especially important for the glass frog because they live in trees. Frogs that live in trees are called arboreal frogs, with arbor being the Latin word for tree.
The sticky toes we were just talking about make arboreal frogs like the glass frog unique. They can jump long distances to escape predators, and their sticky feet will help them immediately stick upon landing instead of bouncing off.
4. Females Choose A Mate By Their Call
Male glass frogs attract females with unique vocal calls, and females select mates based on these calls. Males may accompany their calls with slight limb movements, like waving of the arms or legs, especially when calling from a leaf positioned near water.
Glass frog calls are typically soft, high-pitched, and somewhat insect-like, often resembling a rapid series of clicks, chirps, or peeps. These calls are usually not as loud or pronounced as those of other frogs, blending into the ambient sounds of the rainforest.
5. Females Are Usually Bigger Than Males
There are few noticeable differences between male and female glass frogs. The main difference is males are typically smaller than females.
Females also tend to be a bit fatter than males. So if you see two glass frogs side by side on a leaf, the bigger of the two is likely female.
6. Males Are Very Territorial During Mating Season
Male glass frogs are territorial during the mating season. They establish small territories, typically on leaves overhanging water sources, where they call to attract females. Males will defend these areas against other males, often engaging in physical confrontations that include wrestling and pushing each other off leaves to maintain their space.
This territorial behavior helps ensure that the calling male has a clear area to attract potential mates and increases his chances of being chosen by a female.
7. They Lay Their Eggs On A Leaf, Not In Water
Many species of frogs lay eggs in water, but not the glass frog. After mating, females deposit about 18 to 30 eggs on a leaf that is positioned above the water. When the eggs hatch, the tadpoles roll off the leaf and fall into the water below. After that, they begin their metamorphosis, which can take a few days or a few weeks, depending on the temperature.
8. Males Guard And Care For Eggs
After mating, males stay behind on the leaf and guard the eggs against predators. Males also keep eggs wet and hydrated by transferring moisture from their bellies.
Male glass frogs attract several females to the same leaf to mate. They often end up protecting several different clutches of eggs on one leaf.
9. The Main Threats To Their Eggs Are Frog Flies And Wasps
It is the males job to protect the egg from predators, the two main types being frog flies and wasps.
Frog flies lay their eggs on top of the glass frog egg clutches. Once the fly eggs hatch, the maggots feed on the frog eggs, often leading to significant egg loss in a clutch.
Wasps are attracted to glass frog eggs as a food source. To protect their clutch, male glass frogs will actively guard the eggs and use their legs to kick or swipe at wasps and other small predators, attempting to keep them away.
10. They Glow In UV Light
Some glass frogs appear to glow under UV light, displaying biofluorescence—a phenomenon that absorbs UV light and re-emits it as visible light. This effect, different from bioluminescence where an animal produces its own light, is likely due to proteins in the frogs’ translucent skin. Scientists are still studying this biofluorescence to understand its purpose, though it may help the frogs blend into their leafy surroundings.
11. They Live Up To 10 years in the wild
Glass frogs have a relatively long lifespan for small amphibians, living about 5 to 10 years in the wild. Their effective camouflage helps them evade predators, and they are skilled at making quick jumps to escape danger.
12. Tadpoles Can Take Several Months To Develop
Some species of glass frogs have relatively long larval stages, taking several months to develop into adult frogs. This extended development period can vary depending on environmental conditions, which need to be stable for tadpoles to undergo successful transformation in their adult form. These specific habitat needs, along with predation, contribute to the relatively smaller populations of glass frogs.
13. There Are About 160 Species Of Glass Frog
As of 2024, there are approximately 160 recognized species of glass frogs, classified into 12 genera. Each species of glass frog has unique adaptations suited to its environment. Most live in trees and thrive in warm, humid climates. New species are occasionally discovered, with the Mashpi Glass Frog (Hyalinobatrachium mashpi) identified in 2019 in Ecuador’s cloud forests near the Mashpi Reserve.
14. They Are Nocturnal
Another interesting fact about glass frogs is that they are most active at night. During the day, they hide under leaves and sleep, emerging at night to feed and call for mates. Their soft calls fill the forest, especially during the mating season. Spotting a glass frog in the rainforest is challenging unless you know where and how to look.
15. Are Glass Frogs Poisonous?
There are many amphibians that release toxins in their skin as a defense mechanism. However, glass frogs are not toxic or poisonous and do not rely on toxins for defense. Their primary defense is camouflage, which helps them blend seamlessly into their leafy surroundings. Their translucent skin, especially on the underside, helps them avoid detection by predators, reducing their need for chemical defenses.
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