Torrent sucker frog facts for kids
Quick facts for kids Torrent sucker frog |
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The Amolops torrentis, also called the torrent sucker frog or little torrent frog, is a type of frog. It belongs to the Ranidae family and the Amolops group. This frog lives only in China, specifically on Hainan island. You can usually find them in streams and wet areas nearby.
Male frogs make high-pitched calls to attract females. These frogs have special glands on their skin that can release toxins. Sadly, these frogs face problems like parasites and losing their homes. The IUCN says they are a vulnerable species. This means they need protection, and they are protected by law in China.
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What Makes Them Special
A. torrentis frogs have several features that make them different from other frogs in the Amolops group found in China and southeast Asia.
- They have special glands on their ankles, called tarsal glands.
- Their eardrum (tympanum) has a clear edge.
- When their back legs are tucked in, their ankle joint (tibio-tarsal articulation) reaches past their nose.
- They have a distinct ridge of skin under their ankle.
- Their backs have smooth bumps.
- The tip of their first finger has a special groove.
Male A. torrentis frogs have two white vocal sacs under their throat. These sacs inflate when they call. Female frogs are usually bigger than males. Adult females are less than 42 millimeters long, while adult males are less than 35 millimeters long. The young frogs, called tadpoles, can grow up to 35 millimeters long. Their tadpoles have a special mouth shape and glands on their belly.
Where They Live
A. torrentis frogs are only found on Hainan island in China. They live at different heights, from 80 to 1000 meters above sea level. For example, you can find them in the Limushan nature reserve on Hainan island. While some thought they were in mainland China's Guangdong province, those sightings were later found to be a different, but related, frog species.
These frogs live in medium and large streams. They also live in the wet areas around these streams. They are called "torrent frogs" because they live near fast-flowing water. This fast water creates a lot of background noise. During the day, they often sit on rocks near fast parts of the stream. They might also be on stone walls near waterfalls. Sometimes, they go into the water for a short time and float on top. At night, you can find them on rocks near streams. They also sit on leaves of nearby bushes and plants.
Reproduction
Female A. torrentis frogs lay their eggs in fast-flowing parts of the stream. They choose rocky spots. They lay eggs in holes or openings in piles of rocks. This helps anchor the eggs to stones or soil. It stops the eggs from being washed away by the strong current. Tadpoles also live in similar places in the stream.
Mating
Male Calling
Mating for these frogs happens when males call out. Their calls travel across and around the streams. The call sounds like a sharp, high "squeak, squeak, squeak." Males make these calls day and night during the breeding season.
Male frogs change how often they call when there is more noise. However, they do not make their calls louder. Researchers used recordings of stream noise to study this. The fact that they don't get louder is interesting. It goes against a common idea that animals should get louder when it's noisy. Instead, these frogs call at a higher pitch. This helps their calls stand out from the lower-pitched stream noise. Males like to call from rocks in the river. They choose rocks that match their body color. This makes their white vocal sacs stand out when they inflate them.
Female Preference
Female A. torrentis frogs prefer higher-pitched calls. They like these calls more than lower-pitched ones. This is true no matter how much background noise there is. Females also prefer calls with some stream noise added. However, stream noise by itself does not attract them. This might mean that stream noise helps females. It could make the calls more attractive. River noise is linked to the rocks and plants where the frogs live. This might help females find good places to lay their eggs.
Females probably don't just listen when choosing a mate. Researchers found that both sounds (male calls) and sights (inflated vocal sacs) attract females. But the sounds were more attractive than the sights.
How They Sense the World
Hearing
These frogs rely on their hearing to find mates. Females hear best at frequencies between 1.6 and 2 kilohertz (kHz). They also prefer higher-pitched calls. However, the males' calls are usually even higher, around 4.3 kHz. This difference is a bit of a mystery. It suggests that A. torrentis might have evolved from frogs that didn't live near streams. The loud stream noise might have made them develop high-pitched calls over time.
The frogs' hearing is also affected by temperature. When it's colder, they don't hear as well at lower frequencies. Their hearing is less sensitive, and it takes longer for them to react to sounds. But this temperature effect doesn't happen for higher-pitched calls. This means that temperature changes might not affect their hearing for the calls they prefer. This could be helpful for their breeding behavior.
Glands and Toxins
The skin of A. torrentis frogs contains special proteins. These proteins are similar to a substance called bradykinin. Bradykinin can lower blood pressure and make muscles contract. In the lab, these proteins from the frog's skin made rat muscles contract. These proteins likely help the frog defend itself. When a predator tries to eat the frog, these toxins might make the predator feel sick. This would stop the predator from trying to eat the frog again.
Threats to the Frogs
Parasites
These frogs can get parasites that feed on their blood. One example is frog-biting midges. These midges are attracted to the calls of male frogs. When a midge attacks, the frog moves its limbs to defend itself. These movements include wiggling toes, lifting hind feet, waving arms, shaking limbs, wiping, stretching legs, and flagging feet. Interestingly, female frogs find males who do these defensive movements more attractive.
These frogs also suffer from nematodes, which are a type of worm. Nematodes have been found as cysts in the stomachs of these frogs.
Protecting the Frogs
The IUCN listed A. torrentis as vulnerable in 2019. This means they are at risk. They only live in a small area of about 15,838 square kilometers on Hainan island. Their habitat on Hainan is shrinking and getting worse.
- Main threats:
- Growing crops like rubber, bananas, and areca nuts.
- Cutting down trees for wood and paper.
- Building dams and managing water.
- Pollution from farms and forests.
In the past, people worried that building hydroelectric plants on Hainan would harm the frogs. However, these plants have been built, and no new ones are planned. Also, no major harm to the frog population has been seen from them.
Habitat Loss
More and more rubber, banana, and areca nut farms are being created. This is shrinking the forest homes of A. torrentis. These farms also pollute the habitat with chemicals like herbicides and pesticides. Losing their home is a big problem because these frogs only live on Hainan island.
Conservation Efforts
To help fight habitat loss, A. torrentis frogs live in several protected areas on Hainan. These include nature reserves and forest parks. Also, these frogs are on a special list in China. This list protects wild animals that are important for their economic or scientific value. Being on this list makes it illegal to collect these frogs. This helps to protect them.
