Elopiformes

Elopiformes are an order of ray-finned fishes within the superorder Elopomorpha. The order comprises two extant families, Elopidae (elops or ladyfishes) and Megalopidae (tarpons). They are considered relatively primitive teleosts and share the leptocephalus, a leaf-shaped larval stage, with other elopomorph groups such as eels.

Members of Elopiformes are generally elongated and silvery or metallic in appearance. They tend to inhabit warm, coastal waters and estuaries, with some species migrating into rivers or other brackish environments. The two families differ in size and shape, but both possess a protractile mouth and a streamlined body adapted to cruising and ambush feeding. Their scales are typically cycloid, and they have a paired fin arrangement and a lateral line system typical of many teleosts.

Distribution and ecology vary by species, but elopsids (ladyfishes) and tarpons are found in tropical and subtropical regions worldwide. They are often coastal and estuarine residents, with some populations undertaking seasonal migrations. Tarpons, in particular, are noted for their large size and notable fighting ability, making them popular targets for sport fishing. Tarpons are also capable of gulping air at the surface, an adaptation that allows survival in hypoxic or brackish waters.

Life cycle and reproduction center on the leptocephalus larval stage, which is transparent and leaf-shaped. After metamorphosis, juveniles and adults occupy pelagic or coastal habitats. The order is an important evolutionary group within Elopomorpha, with a fossil record dating back to the Mesozoic and providing insight into early teleost evolution.

Taxonomically, Elopiformes are recognized as a distinct lineage within Teleostei, representing an early branch within elopomorph fishes and contributing to our understanding of teleost diversification.