TERRAPUB Aqua-BioScience Monographs


Vol. 2 (No. 4), pp. 1-94, 2009 doi:10.5047/absm.2009.00204.0001

Ecology of Anguilliform Leptocephali: Remarkable Transparent Fish Larvae of the Ocean Surface Layer

Michael J. Miller

Ocean Research Institute, The University of Tokyo, 1-15-1, Minamidai, Nakano-ku, Tokyo 164-8639, Japan

(Received on May 12, 2009; Accepted on August 3, 2009; Published online on October 31, 2009)

Abstract: This review examines the present state of knowledge about the ecology of anguilliform leptocephali, which are the unique but poorly understood larvae of eels. All eels spawn in the ocean and their leptocephali live in the ocean surface layer. Their presence worldwide and basic biology have not been extensively studied due to their strong ability to avoid standard plankton nets and their fragile transparent bodies. Leptocephali have laterally compressed bodies and contain a high proportion of transparent energy storage compounds. They have diverse morphological features, but appear to feed only on particulate material, such as marine snow or discarded larvacean houses. Some information on their chemical composition, respiration, growth rates, depth distributions, swimming ability, metamorphosis, and recruitment patterns has been reported, which highlights the interesting and unique aspects of leptocephalus larvae. Regional zoogeography and reproductive ecology of adults and ocean currents affect the spatial and temporal distribution patterns of leptocephali, which have long larval durations, but most life histories and larval recruitment behaviors remain undocumented. Their transparency, feeding strategy, and large size seem to be a unique and successful larval strategy, but the abundance and ecological significance of leptocephali in the ocean appear to have been underestimated.

Keywords: leptocephali, Anguilliformes, eels, fish larvae, early life history, larval ecology, larval growth rates, larval distribution, metamorphosis, recruitment


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