Pleuronectiformes

Pleuronectiformes is an order of ray-finned fishes commonly known as flatfishes, including species such as flounders, soles, dabs, turbots, and halibuts. They are found in oceans worldwide, occupying mostly coastal to continental shelf habitats, from temperate to tropical waters, and ranging from shallow lagoons to the outer continental shelf. Most members are demersal, living on or near the seafloor and often exhibiting strong site fidelity.

Morphology and development: Adult flatfishes have laterally compressed bodies and are typically oriented on one side of the body with both eyes on the upward-facing side. Larvae are bilaterally symmetrical and free-swimming; during metamorphosis, one eye migrates to the opposite side, producing the characteristic asymmetry. The eyed side is usually pigmented for camouflage, while the underside is lighter. They possess extended dorsal and anal fins and a continuous lateral line system.

Ecology: Flatfishes are generally ambush predators or scavengers, feeding on crustaceans, small fish, polychaetes, and other benthic organisms. They are often well camouflaged on the substrate, using both morphology and coloration to avoid predators and surprise prey. They contribute to benthic food webs and are prey for larger fishes, marine mammals, and seabirds.

Life cycle: Most species are oviparous, releasing pelagic eggs that hatch into free-swimming larvae. After metamorphosis, juveniles settle to the bottom. Maturity and growth rates vary by species and environmental conditions.

Taxonomy and significance: The order includes several families, notably Pleuronectidae (righteye flounders), Bothidae (left-eyed flounders), Paralichthyidae (large-toothed flounders), Scophthalmidae (turbots), Soleidae (soles), and Cynoglossidae (tonguefishes). Flatfishes are of major commercial importance worldwide, with species such as flounder, plaice, turbot, sole, and halibut widely fished for food.