flatfishes

Flatfishes are a diverse group of marine fishes within the order Pleuronectiformes. They are characterised by a dorso-ventrally flattened body, a normally asymmetric skull, and an eye migration during development. In most species, as they mature, one eye migrates to the other side of the head, so that both eyes are on the upper, upward-facing surface. Adults rest on the seabed on one side, often camouflaged against the substrate.

Habitat and feeding: Flatfishes are demersal, inhabiting sandy, muddy, or seagrass substrates on continental shelves and slopes from shallow coastal waters to depths of hundreds of metres. They are opportunistic predators and feed on crustaceans, worms, molluscs, and small fishes, using camouflage to ambush prey. Many species exhibit seasonal migrations and depth changes.

Diversity and biology: The group includes several families, such as Pleuronectidae (righteye flounders), Bothidae (left-eyed flounders), Paralichthyidae (large-toothed flounders), Soleidae (soles), and Cynoglossidae (tonguefishes). Eye-sidedness distinguishes right-eyed from left-eyed flounders. The fins are typically well developed, and the coloration is often cryptic, matching the substrate.

Reproduction and human use: Most flatfishes spawn eggs that develop in the open water, with pelagic larvae that later undergo metamorphosis and settle to the bottom. They are important commercially and are fished worldwide for food, including species such as plaice, flounder, and turbot. Some species are also raised in aquaculture.