European Eels ... the Story of their (tough) Life

Several species of Anguilla eels are known for their spectacular life history, with a cross Atlantic migration as they undergo their ontogenetic transformations. Confronted with all kind of challenges, including the one having to catch prey, European eels start as non-feeding preleptocephalus larvae. At early feeding, they are equipped with a seemingly poorly functional jaw system that supports odd-ball teeth. Once they reach the glass eel stage, migration starts up-river and phenotypic transformation starts towards the yellow eel phenotype. During this phase, a trophic segregation starts to emerge that is reflected in a divergent phenotype of broad- versus narrowheaded morphs. If everything goes well, they finally transform into silver eels that stop feeding and spend the rest of their life swimming and spawning, until death do them part. In this presentation, an overview is given of structural and functional challenges preleptocephali undergo with their protruding teeth and poorly ossified jaws. The implications of the divergent head phenotypes on feeding performance is discussed, linking it to genetically directed scenarios underlying this pattern. Mapping that ontotrophic ecology and pollution levels, suggests possible consequences on the closing of their life cycle.