Eggs
Released in open water during spawning ascents at dusk.
Four-stage life cycle
Surgeonfish
A colourful fish armed with a sharp spine near the tail
The surgeonfish is named after the scalpel it carries on each side of the caudal peduncle, a formidable defensive weapon.
Life cycle (4 stages)
Larva
A transparent disc-shaped larva drifting for several weeks in the plankton.
Juvenile
The young settles on the reef and develops its final livery.
Adult
It grazes algae alone, in pairs or in large roaming schools.
Physical changes
- Oval, very compressed and deep body.
- Retractable sharp spines on the caudal peduncle.
- Small mouth with comb-like teeth.
- Bright colours: blue, yellow, black depending on the species.
Habitat
- Reef flats
- Lagoons
- Coral slopes
- Areas of strong algal growth
Diet
- Filamentous algae
- Turf algae
- Plant detritus
- Zooplankton for some species
Survival adaptations
- Caudal scalpel that deters predators.
- Teeth adapted to grazing algal turf.
- Schooling to overwhelm territorial fish defences.
- Digestive system specialised in plant matter.
Ecological importance
- Preventing algae from smothering coral
- Helping reefs regenerate after bleaching
- Serving as prey for reef predators
Importance
- Type : Herbivorous bony fish (Acanthuridae family)
- Habitat shift : Pelagic eggs → Planktonic larva → Reef juvenile → Grazing adult
- Role : Major herbivore of the coral reef.
- Without it algae smother coral: it is a pillar of reef resilience.