Engystomops petersi facts for kids
Quick facts for kids Engystomops petersi |
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Physalaemus petersi (Jiménez de la Espada, 1872) |
The Peters' dwarf frog (scientific name: Engystomops petersi) is a small frog that lives in the Amazon rainforest. You can find it in parts of Colombia, Ecuador, and Peru. This frog looks a lot like its close relative, Engystomops freibergi. For a while, scientists even thought they were the same species!
The way scientists group and name these frogs often changes. This is because new species are always forming in the Amazon. This happens partly because of how frogs behave, especially their mating calls. Male calls are very important in helping these frogs find mates.
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About the Peters' Dwarf Frog
Engystomops petersi belongs to a frog family called Leptodactylidae. Before, this group was mixed with other Amazonian frogs like Eupemphix and Physalaemus. This made it tricky to tell different species apart. Scientists used to think Eupemphix paraensis, Eupemphix schereri, and Engystomops petersi were all different. But after looking closely at their bodies, they found out these frogs were actually the same species.
What Do They Look Like?
Peters' dwarf frogs are quite small. Male frogs are about 21 to 31 millimeters (0.8 to 1.2 inches) long from their snout (nose) to their vent (bottom). Females are a bit bigger, measuring 25 to 39 millimeters (1 to 1.5 inches). Their skin color on their back can be different shades. Their skin is bumpy, with small warts and some larger bumps.
These frogs do not have teeth on their upper jaw. Their finger bones have a special T-shape at the ends. They also have two salivary glands, called parotoid glands, which you can usually see. Their fingers are rounded, and their first finger is longer than their second. Their bodies can be thin or a bit chunky. An interesting fact is that some female frogs have hidden eardrums (called tympani), while males have eardrums that stick out.
Tadpole Appearance
The tadpoles of Engystomops petersi have been studied a lot. They are usually the biggest tadpoles among all Engystomops species. A tadpole's body includes its snout, mouth, vent tube, and tail. A typical tadpole is about 22.7 millimeters (0.9 inches) long. Its body makes up a little less than half of its total length.
They have a wide, round snout with nostrils that are slightly discolored around the edges. Their mouth is covered with tiny bumps called papillae, which are arranged in rows. The tadpole's jaw is dark and has a curved, jagged pattern. They also have a vent tube attached to the fin on their belly. Their tails are about 60% of their total body length and have a slightly rounded tip. A special feature of E. petersi tadpoles is that they have clear, oval-shaped glands along their back.
When preserved, these tadpoles are usually dark to light brown. They often have a spotted, mesh-like pattern with speckles on certain parts of their body. Their tail is light brown with speckles, and their fins are clear with thin, thread-like markings.
Where They Live and How New Species Form
The Peters' dwarf frog is a common species. It lives in both old and new forests, especially at the edges of forests. These frogs live on land and are often found hiding in leaf litter on the forest floor. They are active at night and prefer places that are humid (moist).
Even though they live on land, they lay their eggs near water. They like the edges of lakes, ponds, and pools. Male frogs sing their mating calls while floating on their backs in the water.
The Engystomops group of frogs lives in the Andean foothills of Ecuador, Peru, and Bolivia, and also in the Amazon basin in Brazil. Scientists study how new species form in this group by looking at their DNA, their mating calls, and their chromosomes. Engystomops petersi is found in the northwestern part of this group, mainly in northern Peru and Ecuador. Puyo, Ecuador, is a key place for these frogs. Their chromosomes are unique compared to other Engystomops species. They are different from E. freibergi, which lives in southern Peru and Brazil.
Frog Family Tree and Genetics
Scientists believe that how frogs choose their mates plays a big role in how new species of Engystomops frogs develop. Female E. petersi frogs are picky! They can tell the difference between mating calls from their own group and calls from frogs in other places. This behavior, where they prefer certain calls, likely led to new species forming. The genetic differences between Engystomops species also show up in their chromosomes, which have different patterns.
What Do They Eat?
Engystomops petersi frogs eat only termites. This is different from other frogs like the Túngara frog (Engystompos pustulosus), which eats many different kinds of insects. Sometimes, these frogs have been seen eating in groups. In one study in Bolivia, E. petersi frogs were seen eating termites together in a half-circle shape. This is rare for frogs in this area, which usually eat alone among the leaves on the rainforest floor.
Reproduction and Life Cycle
E. petersi frogs breed during the rainy season. The male frog's call has a first part (a "prefix") and a "whine" sound. In some places, their call also has a third "squawk" sound at the end. The eggs are laid in foamy nests.
Mating Calls and Female Choices
Female E. petersi frogs choose mates based on the calls of males from their own species. The special mating call of E. petersi has two main parts. The first part, called the prefix, is one or two short bursts of sound, lasting about 20 to 70 milliseconds. The second part is the whine, which is a lower-pitched, sweeping sound that comes after the prefix. In some areas, E. petersi frogs also add a "suffix" to the end of the whine. This suffix has a higher pitch.
In different areas of Ecuador, the mating calls of E. petersi vary in pitch. This suggests that new E. petersi species might be forming over time in these isolated places.
Female E. petersi frogs usually prefer calls from local males over calls from males in other areas. They don't seem to care as much about different pitches in the calls. They also like complex calls that include a suffix more than simpler calls with just a prefix and a whine. This strong preference for local males shows that these frogs are becoming isolated in their behavior. This is important for understanding how genes change and how new species form quickly in the Amazon.
Genetic Differences
E. petersi frogs are known for their behavioral isolation. Females prefer calls from their own species, which helps them stay separate from other frog species. However, sometimes, different species do mate. This can lead to hybrid frogs that look very similar to their parents. But E. petersi frogs have different chromosome structures compared to other species. This makes it harder for their eggs to be fertilized and for the young to develop properly if they mate with other species. For example, when E. petersi tries to mate with E. magnus or E. selva, fewer eggs are fertilized, and the offspring are less likely to be fertile. This is because the big differences in chromosome structure make the new frogs' chromosomes unstable.
Dangers and How We Protect Them
E. petersi frogs are part of studies to help protect frogs in the Andes mountains. They face a potential threat from an invasive fish called the rainbow trout. These trout have spread into the waters of the Ecuadorian Andes. Rainbow trout can carry a disease called Saprolegnia diclina. This disease can spread to E. petersi tadpoles, causing more of them to die. This can lead to a decrease in the number of frogs in the area. With more rainbow trout farms being built, this is a growing danger for nearby frog species.
Losing their habitat is also a big worry for E. petersi. The forests in Ecuador have lost almost 60% of their area because of deforestation. There are also many legal and illegal mining and logging activities that destroy even more habitat. This is a threat not just to E. petersi but to all the amazing plants and animals in the region. Since E. petersi lives in a relatively small area, losing their habitat could be very bad for this species.
See also
In Spanish: Rana enana de Peters para niños
