Classroom lesson · Wildlife · 🇳🇷 Nauru

Parrotfish

The reef's colourful builders — they make sand with their teeth

Photo · Wikimedia Commons

What is it?

Parrotfish are some of the most colourful creatures on Nauru's coral reef, and they come in dazzling shades of blue, green, pink, and orange. They have a beak-like mouth made of fused teeth — a bit like a parrot's beak — which they use to scrape algae off coral. Here is the amazing part: after they eat the coral rock, they poop out fine white sand. A lot of the beautiful white sand on Pacific beaches was once inside a parrotfish.

Tell me more

Parrotfish are reef engineers. By scraping algae off the coral, they keep the reef healthy and clear. A single parrotfish can produce hundreds of kilograms of sand per year. Scientists estimate that much of the white sand on tropical beaches was created by parrotfish over thousands of years.

At night, some parrotfish wrap themselves in a bubble of mucus — like a sleeping bag made of slime — which helps disguise their scent from predators while they sleep. In the morning, they break out of the bubble and start nibbling the reef again.

Parrotfish can change colour as they grow, and some species can even change sex during their lifetime. The males are often the most brilliantly coloured, flashing electric blue and turquoise as they dart over the reef. Around Nauru's coast, snorkellers sometimes get to swim right alongside them.

In the classroom

Walk your class through this in 15 minutes.

Talk together

Discussion prompts

01Parrotfish make sand as a by-product of eating. Can you think of other animals that accidentally create something useful for their environment?
02A parrotfish sleeps in a slime bubble. What is the most unusual sleeping habit you have ever heard of in the animal world?
03If you could be any coral reef creature for a day, which would you choose and why?

Try this

Classroom activity

Bring a handful of fine white sand to class (or look at a close-up photo). Imagine each grain was once part of a coral reef scraped up by a parrotfish. Draw the journey: coral reef → parrotfish beak → parrotfish tummy → sand grain → beach. Label each stage.

Parrotfish

Walk your class through this in 15 minutes.

Discussion prompts

Classroom activity

Other things that make Nauru special

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