How cleaner fish help maintain coral reefs
How cleaner fish help maintain coral reefs
Learn about cleaner fish and remora, two fishes often found in coral reefs.
Contunico © ZDF Studios GmbH, Mainz; Thumbnail © Wirestock/Dreamstime.com
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Contunico © ZDF Studios GmbH, Mainz; Thumbnail © Wirestock/Dreamstime.comLearn about cleaner fish and remora, two fishes often found in coral reefs.
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Contunico © ZDF Studios GmbH, MainzLearn about the grey (or gray) reef shark, including its mating behaviours.
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Contunico © ZDF Studios GmbH, MainzLearn about the elephant seals of Guadalupe Island, off the northwestern coast of Baja California, Mexico.
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Encyclopædia Britannica, Inc.What is food for a mushroom? That depends.
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Contunico © ZDF Studios GmbH, MainzLearn about basking sharks.
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Contunico © ZDF Studios GmbH, MainzThe waters off Malpelo Island, Colombia, are home to a diverse marine life, which includes the scalloped hammerhead shark.
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Contunico © ZDF Studios GmbH, MainzLearn about butterflyfish and squirrelfish.
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Encyclopædia Britannica, Inc.Learn about the role spiders play as predators in the food chain.
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© Sam Cossman (A Britannica Publishing Partner)Ecological succession happens when new life takes over an environment. Here, a sunken ship demonstrates the process in a tropical coral reef.
News •
Scientists say they have discovered 20 new species deep in the Pacific Ocean
• Dec. 22, 2025, 1:26 AM ET (NPR)
Transcript
Hundreds of thousands of organisms live tightly packed together around the coral reefs of the tropics. They live according to a complex set of rules and interrelationships. It goes far beyond who’s eating whom.
Coral reefs are like the metropolises of the sea. Their inhabitants range from microscopic invertebrates to a sheer unbelievable diversity of reef fish. This stunning multitude of colors and shapes has given coral reefs the name rainforests of the sea. Even big predators like sharks live here.
Coral reef residents communicate using their specific shapes, colors and movements. Cleaner fish, for example, get themselves noticed with their erratic movements. They play a vital role in the life of the reef. They live off parasites and excess tissue that they meticulously pick off the skin, fins, teeth and gills of a huge variety of fish. They form cleaning stations and are untouchable due to their special position within the reef system. Only they can approach big predators without running the risk of becoming their next meal. Even when they do their work right inside the jaws of a predator, they’re safe. Cleaner fish are part of every healthy coral reef. Their relationship with their hosts has an advantage for both sides. The cleaner fish get fed, and the reef residents are freed of annoying parasites and dermatological problems.
This shark is also giving a ride to a remora. They’re often found travelling with sharks and it’s likely that they, too, eat the tiny parasites found on the shark’s skin. When grey reef sharks take a rest in the current, any sudden movements are often in response to their escorts, the remoras. They’re trying to tell the remoras not to be too bothersome. For the remoras, the sharks are ideal transport – but they make sure to stay away from the teeth. There could well be some parasites between this shark’s gills. Again, the host puts up with the cleaning operation until he’s had enough. These visitors to the sensitive gills could certainly be unpleasant.
Cleaning inside the dangerous shark-jaws falls to real specialists – the cleaning wrasse. They wait for the shark to open its jaws wide. Eventually, the shark is on its way once again, content and clean.
Coral reefs are like the metropolises of the sea. Their inhabitants range from microscopic invertebrates to a sheer unbelievable diversity of reef fish. This stunning multitude of colors and shapes has given coral reefs the name rainforests of the sea. Even big predators like sharks live here.
Coral reef residents communicate using their specific shapes, colors and movements. Cleaner fish, for example, get themselves noticed with their erratic movements. They play a vital role in the life of the reef. They live off parasites and excess tissue that they meticulously pick off the skin, fins, teeth and gills of a huge variety of fish. They form cleaning stations and are untouchable due to their special position within the reef system. Only they can approach big predators without running the risk of becoming their next meal. Even when they do their work right inside the jaws of a predator, they’re safe. Cleaner fish are part of every healthy coral reef. Their relationship with their hosts has an advantage for both sides. The cleaner fish get fed, and the reef residents are freed of annoying parasites and dermatological problems.
This shark is also giving a ride to a remora. They’re often found travelling with sharks and it’s likely that they, too, eat the tiny parasites found on the shark’s skin. When grey reef sharks take a rest in the current, any sudden movements are often in response to their escorts, the remoras. They’re trying to tell the remoras not to be too bothersome. For the remoras, the sharks are ideal transport – but they make sure to stay away from the teeth. There could well be some parasites between this shark’s gills. Again, the host puts up with the cleaning operation until he’s had enough. These visitors to the sensitive gills could certainly be unpleasant.
Cleaning inside the dangerous shark-jaws falls to real specialists – the cleaning wrasse. They wait for the shark to open its jaws wide. Eventually, the shark is on its way once again, content and clean.
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