Pleuronectiformes (Flatfishes · Order Overview)

Details

Pleuronectiformes—the flatfishes (flounders, soles, turbots, halibuts)—are defined byeye migration during metamorphosis. Larvae are bilaterally symmetric; as they develop, one eye moves to the other side and juveniles settle to the bottom, adopting a lateral, asymmetric body plan.

Ecology & Biology

• Diet: mostly benthic predators of fishes, crustaceans, molluscs and polychaetes; some take detritus.

• Reproduction: predominantly pelagic spawners; eggs/larvae are planktonic, with post‑metamorphic settlement.

• Behaviour: adept at crypsis and partial burial; many species are crepuscular/nocturnal foragers.

Identification

• Eye side: adults bear both eyes on one side (“right‑eyed” vs “left‑eyed” clades). Pleuronectidae are usually right‑eyed; Bothidae mostly left‑eyed (with exceptions).

• Body: extremely laterally compressed, oval to rhomboid; long dorsal/anal fins along the margins; mouth/teeth vary with feeding mode.

• Camouflage: the eyed (upper) side can change colour/pattern to match the substrate; blind (lower) side is typically pale.

Size & Longevity

• Length: from 10–20 cm soles to over 2 m (e.g., halibuts).

• Life: commonly 5–20 years, longer in large cold‑water taxa.

Range & Habitat

Worldwide on continental shelves and slopes over sandy/muddy bottoms, from tropics to polar seas; a few species enter estuaries or freshwaters.

Fisheries & Management

• Value: many families support major food fisheries (halibut, turbot, plaice, soles).

• Management: bottom trawls impact habitats; combine size limits, seasonal closures, spatial protections and habitat restoration.

IUCN: this is an order‑level overview; statuses vary widely among species (LC–EN). Marked here as Not Evaluated (NE).