The members of this diverse group of 632 species are linked by a special form of larval development. The planktonic larvae are thin, transparent and leaf-like drifting with the currents. Adults inhabit a wide array of habitats and undergo long migrations.

2. Metamorphosis of the eel, Anguilla rostrata (Family Anguillidae).

3. Skull of a Conger eel, Conger vulgaris (Family Congridae).