Agkistrodon piscivorus

The cottonmouth is a large snake.

It lives near slow water. It likes to swim in lakes and streams.

Young snakes have bright colors. They may have dark stripes.

The tip of their tail is yellow. They wiggle their tails to trick prey.

Adult snakes look different. They are often dark or brown. Their stripes fade as they grow old.

This snake can be dangerous. It has a bite that can hurt. It may show its white mouth to stay safe.

It is a very good swimmer. It can even swim between islands.

The cottonmouth is a large snake.

It lives in the southeastern United States. This snake likes to stay near water. You can find it in slow lakes, streams, and marshes. It is a very good swimmer. It can even swim between islands and the mainland.

Young snakes look different than adults. They have bright colors. They may have dark stripes on their bodies.

The tip of their tail is often yellow. Young snakes wiggle their tails to lure prey. This helps them catch food.

Adult snakes are often dark. They can be olive-brown, gray-brown, or black. Their stripes fade as they get older. Most adults have a bulky, triangular head.

This head is easy to see from its neck.

Cottonmouths are pit vipers. This means they are venomous snakes. They can give a painful bite if they feel unsafe. When they feel threatened, they may coil their bodies. They might also open their mouths wide. This shows the white lining inside. This is a way to tell others to stay away.

The cottonmouth is a fascinating snake found in the southeastern United States.

It is a semiaquatic pit viper, which means it spends much of its time in or near water. You can find these snakes in slow-moving lakes, streams, and marshes. They are very capable swimmers. Some even swim between barrier islands and the mainland through bays and estuaries. This snake is quite large and can deliver a painful, potentially fatal bite.

This snake has a very interesting way of protecting itself. When it feels threatened, it may coil its body up. It might also display its fangs to warn others. A common behavior is called gaping. This is when the snake opens its mouth wide to show the white lining inside.

This display tells intruders to stay away. Some people call this snake a "gapper" because of this action. It is a strong way to say, "Please leave me alone."

Scientists have studied these snakes for a long time. The name *Agkistrodon piscivorus* comes from old languages. The first part comes from Greek words for "hook" and "tooth." The second part comes from Latin words meaning "fish" and "to eat greedily." This means the name translates to "hook-toothed fish-eater." For many years, experts thought there were three different subspecies. These were the eastern, western, and Florida cottonmouths. However, a study in 2014 used DNA to change how we group them. Now, scientists recognize two different species instead of three.

There are many specific facts about how these snakes look.

Adult males can reach an average body mass of 450 grams. Females are usually smaller than the males. One very large specimen was measured at 189.2 centimeters long. The snake's head is bulky and triangular. This shape is very different from its neck. Even though it lives in water, it does not have a narrow head. The scales on its back have ridges called keels.

Young cottonmouths look very different from the adults.

They often have bright colors like tan, brown, or reddish-brown. They also have dark crossbands across their bodies. The tip of a young snake's tail is usually yellowish or greenish. Young snakes use a clever trick to find food. They wiggle the tips of their tails to lure prey closer. This is a great way to catch a meal. As they grow older, their bright colors fade into darker shades.

The cottonmouth, scientifically known as *Agkistrodon piscivorus*, is a unique species of venomous pit viper.

It belongs to the subfamily Crotalinae and the family Viperidae. This snake is one of the few semiaquatic vipers in the world. It is native to the Southeastern United States. You can find them in slow-moving and shallow waters. These include lakes, streams, and marshes. They are also very capable swimmers. Some individuals even swim between barrier islands and the mainland through bays and estuaries.

This snake has a very distinct physical structure. It is the largest species within the *Agkistrodon* genus. Adults often exceed a certain length, and females are typically smaller than males. One study found that males have an average body mass of 450 grams. Females have an average mass of 315 grams. While most are average in size, some can be much larger. A record specimen was measured at a total length of 189.2 cm.

Large specimens can be extremely bulky. One snake measuring about 150 cm in length weighed approximately 1,000 grams. The head is bulky and triangular. This head shape is distinct from the neck. The snout is blunt in profile. Even though it lives in water, its head is not narrow. This contradicts what many might expect for an aquatic animal.

When a cottonmouth feels threatened, it uses specific behaviors to protect itself. It may coil its body and display its fangs. A common behavior is called gaping. During gaping, the snake opens its mouth wide to show the white lining inside.

This action is why some people call the snake a "gapper." It is a defensive display intended to warn intruders. Because of this, many common names refer to this threat display. Names like "cottonmouth" or "gaper" come from this white mouth lining. Some people also call them "water moccasins." However, many scientists dislike that name. It can cause confusion with nonvenomous water snakes.

Young cottonmouths look quite different from the adults.

They often have high-contrast colors like tan, brown, or reddish-brown. They also have dark crossbands across their bodies. The tip of a juvenile's tail is usually yellowish or greenish. As the snake grows, these bright colors fade. Older individuals become a more uniform olive-brown, grayish-brown, or black. Young snakes also use a clever trick to hunt. They wiggle the tips of their tails to lure prey animals closer.

This behavior helps them catch meals more easily.

The history of how we name this snake is quite complex. The scientific name *Agkistrodon piscivorus* comes from two different languages. The genus name comes from Greek words meaning "hook" and "tooth." The specific name comes from Latin words meaning "fish" and "to eat greedily." Therefore, the name translates to "hook-toothed fish-eater." For a long time, scientists recognized three subspecies. These were the eastern, western, and Florida cottonmouths. However, a molecular study in 2014 changed this. By looking at DNA, researchers applied phylogenetic theories. This study changed the long-standing taxonomy. Now, scientists recognize only two species.

Under the current taxonomic arrangement, the western cottonmouth is no longer a separate subspecies. It was merged with the eastern cottonmouth into one species. The Florida cottonmouth is now recognized as its own separate species.

This change was based on studying gene flow. The Florida cottonmouth is found in southern Georgia and the Florida peninsula. The northern cottonmouth lives in various parts of the United States. This includes the Atlantic Coastal Plain and the lower Piedmont. It also reaches into areas like Oklahoma and Indiana.

It is important to distinguish the cottonmouth from other similar animals. The copperhead is a common species that people often confuse with the cottonmouth. This is especially true with juvenile snakes. You can tell them apart by looking at the head. The cottonmouth has broad, dark stripes on the sides of its head. These stripes extend back from the eyes. In contrast, the copperhead has only a thin, dark line. You might also see them near water snakes of the genus *Nerodia*. These water snakes have round pupils and different scale patterns. Understanding these differences helps people identify the venomous cottonmouth correctly.