River shark

Some sharks live in rivers. They swim in muddy water.

These sharks live in Asia and Australia. They also live near the sea. Some stay in fresh water only.

These sharks are hard to find. People thought they were gone. Then, people found small groups again.

One type lives in the Ganges River. This river is a place where babies are born.

Fishing and dirty water can hurt them. We must help keep their homes safe. Do you like rivers?

River sharks are a special group of sharks. They belong to the genus Glyphis. These sharks live in rivers and near the sea. Most live in Southeast Asia and Australia. Some are even found in Africa.

These sharks are hard to find. They are very secretive. For a long time, people thought they were extinct. Extinct means they were all gone. But people found small groups in the late 1900s. They found them in Borneo and Northern Australia.

Some river sharks live in fresh water only. The Ganges shark is one of these. It uses the Ganges River as a nursery. A nursery is a safe place for babies to grow. Other types, like the speartooth shark, live in salt water too.

These sharks like muddy water. This water has low salinity. Salinity is how much salt is in the water. Many river sharks face big problems. Fishing and pollution can hurt them. In India, many sharks are caught. This makes it hard for river sharks to thrive.

River sharks belong to a group called Glyphis. These sharks are very special. They live in rivers or near the coast. Many live in Southeast Asia and Australia. Some have even been seen in Africa. They are different from the bull shark. People sometimes call the bull shark a river shark too. But the Glyphis sharks are their own group.

These sharks like a specific way of life. They often live in muddy waters. This water has low salinity. Salinity is the amount of salt in the water. Some species stay in fresh water only. The Ganges shark is one of these. Other sharks like the speartooth shark live in salt water too. They are often born around October.

Scientists have studied these sharks for a long time. The Ganges shark was named in 1839. The Irrawaddy River shark was named in 1896. There are also extinct species like Glyphis hastalis. That shark was named in 1843. Researchers found the Borneo river shark in 2010. These names help us keep track of each kind.

Finding these sharks is a hard job. They are very secretive animals. People thought they were extinct for a long time. Then, small groups were found in the late 20th century. They were seen in Borneo and Northern Australia. These sharks live in nine different tidal areas. They are found in South Asia and New Guinea.

Many things make life hard for these sharks. The Ganges shark uses the Ganges River as a nursery. A nursery is a place for babies to grow. But fishing and pollution cause big problems. This happens in the Northern Arabian Sea. India is a place where many sharks are caught. It is one of the top three shark catchers.

The genus *Glyphis* contains a group of animals known as river sharks. These sharks belong to the family Carcharhinidae. They are distinct from the bull shark, which is also sometimes called a river shark. While bull sharks and *Glyphis* sharks may live in the same river systems, they are different groups. These sharks are unique because they inhabit rivers and coastal regions. They are often found in parts of Southeast Asia and Australia. Some reports even place them in the Zambezi River in Africa.

River sharks prefer very specific environments to survive. They are often found in nine different tidal areas. These areas usually consist of muddy waters with low salinity. Salinity refers to the amount of salt present in the water. Some species stay in freshwater environments. For example, the Ganges shark is restricted to freshwater. Other species, like the northern river shark and the speartooth shark, can also live in coastal marine waters. Their presence in coastal areas suggests they are usually born around October.

Scientists use taxonomy to organize and name the different species within *Glyphis*. The genus is considered to be most closely related to the genus *Lamiopsis*. Currently, there are several recognized species in this group. These include the Borneo river shark, the Ganges shark, the northern river shark, the speartooth shark, and the Irrawaddy River shark. There are also known extinct species, such as *Glyphis hastalis* and *Glyphis pagoda*. The exact number of species might be higher than what scientists currently accept. However, the secretive habits of these sharks make research very difficult.

Taxonomy is a changing field as new studies provide more information. Scientists once thought there were five different species in this genus. Later, molecular studies changed this understanding. These studies revealed that *Glyphis gangeticus* has an irregular distribution in the Indo-West Pacific region. Because of this, the Bornean and Irrawaddy River sharks may actually be variations of *Glyphis gangeticus*. Despite these findings, some scientific authorities still choose to keep these species separate.

History shows how long humans have been studying these animals. The Ganges shark was first described by J. P. Müller and Henle in 1839. The Irrawaddy River shark was named by Steindachner in 1896. Other species have been identified much more recently. For instance, Compagno, White, and Cavanagh described the Borneo river shark in 2010. For a long time, researchers actually believed these sharks were extinct. It was not until the end of the 20th century that small populations were rediscovered in Borneo and Northern Australia.

Conservation is a major concern for the survival of river sharks. Many populations are currently very poorly known to researchers. The Ganges shark uses the Ganges River as nursery grounds. A nursery is a place where offspring are born and raised. Unfortunately, these populations have been severely diminished. This decline is caused by a long history of fishing and pollution issues in the Northern Arabian Sea. These environmental pressures make it difficult for the sharks to maintain healthy numbers.

Fishing activity also plays a significant role in shark populations. India is a major location for these activities. It is reported to be one of the top three greatest shark and ray capturers in the world. In fact, India accounts for up to nine percent of reported global landings for these animals. This high level of fishing, combined with pollution, creates a difficult environment for the genus *Glyphis*. Understanding their distribution and habitat is vital for protecting these secretive creatures.