Revista Chilena de Historia Natural 76 (2): 169-175, 2003
SIMPOSIUM
Delayed metamorphosis in decapod crustaceans: evidence and
consequences
Most marine invertebrate species exhibit a complex life cycle including a planktonic larval
phase and a benthic juvenile-adult phase. Metamorphosis and settlement are the links between these phases of development. In many
species, metamorphosis is triggered by specific chemical and/or physical cues, mainly associated with the adult habitat. In the
absence of such cues, competent larvae can delay their metamorphosis by a few days to several months. Most investigations on the
delay of metamorphosis have been realised on sessile or sedentary species. In relation to mobile decapod crustaceans, the number of
such studies is low, probably because the members of this group retain their mobility after metamorphosis, and hence, may depend
less on enviromental cues for the induction of settlement and metamorphosis. Nevertheless, the larvae of some decapod species have
been shown to depend on metamorphosis-stimulating cues. These include special types of substrates, physical or chemical traits of
particular (e.g., estuarine) water bodies, as well as odors from conspecific or congeneric adults. The capacity for delay is, in the
decapod species studied so far, limited and may normally end with spontaneous metamorphosis. An extended time of larval
development presents the advantage of enhancing the probability for locating a suitable habitat, but it may imply, as a disadvantage, a
reduction of juvenile growth or survival and a prolonged development time preceding benthic life. This paper reviews the available
evidence for delayed metamorphosis in decapod crustaceans, indentifed cues, the importance of larval age at the time of contact with
a cue, and costs of delayed metamorphosis. Additionally, we propose new frontiers for future investigations on delayed metamorphosis
in decapod crustaceans, including the molecular identification of chemical cues, the identification of the stage(s) of the moulting cycle
that is or are sensitive to such cues, the study of hormonally mediated effects on the moulting cycle, the quantification of energetic or
other costs of delayed metamorphosis, and the analysis of relationships between the effectiveness of adult odors and phylogenetic
proximity of larvae and adults.
Key words:
delayed
metamorphosis, Crustacea, larvae
