Parrotfish: a two-minute wildlife lesson

Coral Reef · day 5 of 7

Five facts

1. A green humphead parrotfish can produce about 90 kg of sand each year, after grinding coral or rock with its jaws.
2. At night, some parrotfish spin a mucus cocoon around their whole body that is thought to mask their scent from predators like moray eels.
3. Parrotfish bite with a beak of tightly packed teeth, and their teeth grow continuously to replace the worn parts.
4. The green humphead is the giant of the parrotfish: up to 1.3 m long in total, though it is commonly about 0.7 m.
5. On the Great Barrier Reef, parrotfish are the only fish group that routinely scrape and clean inshore coral reefs.

The quiz

1. How much sand can a green humphead parrotfish produce in a year?

• About 9 kg
• About 90 kg (correct)
• About 900 kg
• About 1 kg

It can produce about 90 kg of sand each year.

2. What do some parrotfish spin around themselves at night?

• A mucus cocoon (correct)
• A silk web
• A bubble net
• A sand tent

Some parrotfish spin a mucus cocoon at night, thought to mask their scent.

3. What happens to parrotfish teeth as they wear down?

• They fall out for good
• They turn into a hard shell
• They are swallowed whole
• They grow continuously (correct)

Their teeth grow continuously, replacing the worn parts.

4. How long can a green humphead parrotfish grow?

• Up to 0.3 m
• Up to 5 m
• Up to 1.3 m (correct)
• Up to 0.7 m, never more

The green humphead reaches up to 1.3 m in total length.

5. What job do parrotfish do on the Great Barrier Reef?

• They guard the corals from sharks
• They scrape and clean inshore coral reefs (correct)
• They build new reefs
• They hunt other fish

Parrotfish are the only fish group that routinely scrape and clean inshore coral reefs.

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