Piranha

Piranhas are fish that live in South American rivers.

They have very sharp teeth. These teeth are shaped like blades. They use them to tear food.

Piranhas eat many things. They eat fish, but they also eat plants and seeds. Some piranhas even eat insects.

They are not always scary hunters. Many fish swim in groups to stay safe. This helps them hide from bigger animals. Piranhas are very interesting fish to learn about.

Piranhas are famous fish from South American rivers.

Many people think they are scary hunters. They often swim in groups called schools. Scientists found these fish school to stay safe. They want to hide from larger animals.

Piranhas are omnivorous. This means they eat both plants and animals. They eat fish, insects, and even seeds. Some piranhas even eat the scales of other fish. Most piranhas grow to be quite small. The red-bellied piranha can reach about 35 centimeters long.

Their teeth are very special. They have one row of sharp, triangular teeth. These teeth fit together like scissors. This helps them tear their food quickly. Piranhas also have very strong jaws. This gives them a powerful bite. They use these strong jaws to help them eat. Some people even use piranha teeth as tools. They use them to carve wood or cut hair.

Piranhas are famous freshwater fish from South America.

They live in many places like the Amazon basin and the Orinoco River. These fish can be found in rivers, lakes, and even floodplains. While many people think they are scary hunters, they are actually omnivorous. This means they eat a mix of things. They eat fish, insects, and even small animals like birds or reptiles. They also eat plants, seeds, and fruit.

A piranha's body is built for eating. They have a single row of sharp teeth in each jaw. These teeth are triangular and look like little blades. The teeth are packed tightly together and interlock. This helps them puncture and tear food very quickly.

They also have very large jaw muscles. These muscles are attached close to the tip of the jaw. This setup gives them a very strong bite. The black piranha has one of the strongest bites for its size.

People have known about these fish for a long time. The name piranha comes from the Old Tupi word *pirãîa*. In a 1585 dictionary, this word was used to mean scissors. An explorer named Gabriel Soares de Sousa wrote about them in 1587. The word first appeared in English books in 1710. Scientists are still studying them today. They are still finding new species of piranha. Estimates say there are between 30 and 60 different types.

Most piranhas are not very large. Many species grow to be between 10 and 25 centimeters long. The red-bellied piranha is one of the biggest. It can grow up to 35 centimeters. A long time ago, an extinct fish called Megapiranha lived. It was much larger than today's piranhas. Some people say piranhas in the São Francisco River reach 40 centimeters. However, the largest fish that scientists have actually confirmed are much smaller.

Piranhas are part of our world in many ways. Some people catch them to eat as food. In the Amazon, they are even sold at markets. Some tribes in Brazil and Bolivia use piranha teeth as tools. They use them to carve wood or even cut hair.

Other people keep them as pets in aquariums. However, keeping them can be hard. They can be aggressive toward each other. In some places, like the Philippines, it is illegal to import them. This helps protect the local environment from new fish.

Piranhas are a group of freshwater fish belonging to the subfamily Serrasalminae. They are part of the family Serrasalmidae and the order Characiformes.

These fish live in South American river systems, such as the Amazon and Orinoco basins. They also inhabit floodplains, lakes, and reservoirs. While many people believe piranhas are strictly predatory hunters, they are actually omnivorous. This means they eat a wide variety of things. Their diet includes fish, insects, crustaceans, and even other vertebrates like mammals or birds. They also consume plant material like seeds, fruits, and leaves.

The physical structure of a piranha is specialized for eating. They possess a single row of sharp teeth in both their upper and lower jaws. These teeth are tightly packed and interlock with one another. Most species have tricuspid teeth, which means they have three points or cusps. This creates a triangular, blade-like shape that is perfect for rapid puncture and shearing. The genus Pygopristis is an exception, as it has pentacuspid teeth with five points.

Their biting strength is also remarkable. The black piranha, or Serrasalmus rhombeus, has one of the most forceful bites relative to its body mass among all vertebrates. This power comes from large jaw muscles called adductor mandibulae. These muscles attach close to the tip of the jaw to create a mechanical advantage for force.

Taxonomy, or the science of naming and grouping living things, is complex for piranhas. Traditionally, scientists only called four genera "true" piranhas: Pristobrycon, Pygocentrus, Pygopristis, and Serrasalmus. This was based on their unique teeth. However, recent genetic analysis has changed these views. To make the group monophyletic, which means all members share a single common ancestor, the group might need to be restricted or expanded. Currently, most members of the Serrasalminae subfamily use "piranha" in their names. This excludes the most basal members, known as silver dollars. The exact number of species is still debated, with estimates ranging from fewer than 30 to more than 60.

History shows that humans have interacted with piranhas for centuries. The name comes from the Old Tupi word *pirãîa*, which was used in a 1585 dictionary to mean scissors. In 1587, the Portuguese explorer Gabriel Soares de Sousa provided the first formal description of the fish. The word eventually entered English literature in 1710.

Piranhas have also been found in unexpected places far from South America. They have been discovered in Kaptai Lake in Bangladesh and the Lijiang River in China. Some researchers believe rogue fish traders may have released them in Bangladesh to avoid detection by authorities.

Size varies greatly depending on the specific species. Most piranhas grow to a length between 10 and 25 centimeters. The red-bellied piranha is a larger species that can reach up to 35 centimeters. While some claim São Francisco piranhas reach 40 centimeters, confirmed specimens are smaller. In the distant past, an extinct species called Megapiranha lived 8 to 10 million years ago. This prehistoric fish was much larger, potentially reaching lengths of 100 centimeters or more.

Piranhas have interesting social behaviors and ecological roles. Many people think they form schools to hunt cooperatively. However, recent research suggests they actually school for protection. They group together to stay safe from predators like dolphins, caimans, and cormorants. Some species are solitary, while others live in small groups. Their diet often changes as they grow. For example, some species like Serrasalmus elongatus are specialized scale-eaters that focus on the fins and scales of other fish. During the breeding season, piranhas dig pits in the substrate to lay their eggs and swim around to protect them.

Humans use piranhas in several ways, though they can also be a nuisance. Many South American tribes, such as the Camayura and Shavante, use piranha teeth as tools for carving wood or sharpening darts.

Piranhas are also a common food source and are sold in markets. However, they can damage fishing gear and steal bait. While they are kept as pets, they can be very aggressive. In aquariums, it is best to keep them in groups of four or more to prevent fighting. In some countries, like the Philippines, importing them is illegal to prevent them from spreading in the wild.