Coastal fish

Many fish live near the shore.

They stay in shallow water. This water is near the land.

Some fish live in rock pools.

These pools stay when the tide goes out. A fish called a blenny lives here. It can even crawl on land!

Other fish live where rivers meet the sea.

These places are called estuaries. They have lots of food for young fish.

Some fish live near bright coral reefs. These fish are very colorful. They hide in the reefs to stay safe.

Coastal fish are the most common in the world. They are fun to find!

Coastal fish live in the sea near the land.

They live on the continental shelf. This is the part of the ocean floor near the shore. These fish are the most common in the world.

They live in many places like sandy shores or coral reefs.

Some fish live in rock pools. These are small pools of salty water left by the tide. The common blenny lives here. It has smooth skin with soft slime. This slime helps it stay moist so it can breathe out of water.

Other fish live in estuaries. An estuary is where a river meets the sea. These areas have lots of nutrients, which are things that help life grow. This makes them great nursery grounds for young fish.

Many fish also live near coral reefs.

These reefs are home to many species. One group is called anthias. They are small and colorful. All anthias are born female. If a male dies, a large female can change into a male. This helps the group stay strong.

Coastal fish live in the sea near the land.

They stay between the shoreline and the edge of the continental shelf. This shelf is the part of the ocean floor near the coast. These fish are the most abundant in the whole world. They live in the sunlit epipelagic zone because the shelf is not very deep.

This area includes many places like sandy shores, rocky coastlines, and coral reefs. It also includes tidal pools, fjords, and estuaries.

Many different habitats support these living things.

In estuaries, rivers meet the sea to create a mix of fresh and salt water. This makes the water rich in nutrients. These nutrients help many things grow. Many fish use estuaries as nursery grounds to grow up safely. Some fish are anadromous, meaning they live in the sea but swim up rivers to spawn. Others are catadromous, meaning they live in rivers but return to the sea to breed.

High productivity also happens in inshore waters because of upwelling.

Rock pools offer a special home for hardy species.

These pools are small areas of salty water trapped in rocks by the tide. Some fish are temporary residents here. For example, the rock goby is a small fish that hides under stones. The long-spined sea scorpion has four long spines on its gill covers. It also has finger-like organs near its mouth to help it catch food.

The common blenny is another resident that can crawl on land using its fins. It has soft slime to keep its skin moist so it can breathe out of water.

Coral reefs are another amazing place for coastal fish.

These reefs occupy less than one percent of the ocean surface. However, they provide a home for 25 percent of all marine fish species. Many fish there are very colorful. One group is called anthias. They are small and peaceful fish that eat zooplankton.

They live in groups called harems. A single colorful male might lead a group of females.

Nature has clever ways to help these fish survive.

Anthias are protogynous hermaphrodites, which is a way to change sex. This means they are all born female. If the dominant male dies, the largest female changes into a male. This helps the group keep its structure. Other fish use camouflage to stay safe. The lumpsucker is a portly fish that looks like a stone. It has a sucking disc on its underside to cling to surfaces.

These special traits help coastal fish thrive in their changing homes.

Coastal fish, also known as inshore or neritic fish, are incredibly abundant.

They inhabit the marine waters between the shoreline and the edge of the continental shelf. Because the continental shelf is usually shallow, these fish are mostly epipelagic. This means they live in the sunlit epipelagic zone of the ocean. They are distinct from oceanic or offshore fish. Those fish live in the deep seas far beyond the continental shelves. Coastal fish thrive in diverse areas like tidal pools, fjords, and estuaries. They also live near sandy shores, rocky coastlines, and coral reefs.

These fish exist in habitats with very high biological productivity. This productivity often comes from upwelling. Upwelling is a process that brings nutrients to the surface. Shoreline runoff also brings many nutrients into these coastal waters. These nutrients support forage fish, which are small fish that serve as food. Predators then feed on these forage fish. Some coastal fish are partial residents. They might spawn in streams, estuaries, or bays. However, most species complete their entire life cycles within the coastal zone.

One specific habitat is the intertidal zone. This area is found along rocky shores. It contains indentations called rock pools. These pools trap salty water when the tide goes out. Rock pools are miniature ecosystems. They are home to hardy plants and animals like seaweed and sea anemones. Many fish are only temporary residents in these pools. The tide eventually carries them to a new location. The rock goby is one such small fish. It is about 5 centimeters long and lives in northern temperate waters.

Other fish have developed amazing ways to survive in rock pools. The common blenny is a territorial fish. It can actually crawl on dry land using its paired fins. It has smooth skin covered in soft slime. This slime prevents the fish from drying out. As long as the skin stays moist, the blenny can breathe out of water. The long-spined sea scorpion is another resident. It is a stout fish that grows about 10 centimeters long. It has four long spines on its gill covers. It also has finger-like organs near its mouth to help catch prey.

Estuaries are another vital coastal habitat. An estuary is a partly enclosed body of water. It occurs where a river or stream flows into the sea. This creates a transition zone of brackish water. Brackish water is a mix of fresh and salt water. Estuaries are subject to marine influences like tides and waves. They also feel riverine influences like freshwater flow and sediment. These combined factors provide high levels of nutrients. This makes estuaries very productive natural habitats. Many fish use estuaries as nursery grounds to grow up safely.

Some fish must travel between different water types. These species are called anadromous or catadromous. Anadromous fish, like salmon, live in the sea but swim up rivers to spawn. Catadromous fish, like eels, live in rivers but return to the sea to breed. To survive in estuaries, fish must be euryhaline. This means they are tolerant of a wide range of salinities. In warmer climates, estuaries often feature mangrove swamps. Specialized fish like mudskippers forage on land in these areas. Archer fish even spit at insects to knock them into the water.

Coral reefs are perhaps the most diverse coastal habitats. They occupy less than one percent of the ocean surface. Yet, they provide homes for 25 percent of all marine fish species.

Reef fish have many specializations to survive. Some, like the anthias, are very colorful. Anthias are protogynous hermaphrodites. This means they are all born female. If the dominant male dies, the largest female changes into a male. This change is driven by surging testosterone. They often live in groups called harems. A single male may lead a group of two to 12 females.