The contrariwise life of a parasitic, pedomorphic copepod with a non‐feeding adult: ontogenesis, ecology, and evolution

Abstract

Abstract. The extraordinary parasitic metanauplius larva of Caribeopsyllus amphiodiae is sexually dimorphic, with conspicuous gonads, and elaborate lens‐bearing eyes. The parasites usually occur singly within their host, and grow for ≤5 months within the stomach of burrowing ophiuroids (Amphiodia urtica). They transform into free‐living, semelparous, non‐feeding adults that live only 2 weeks. The species' life‐history pattern, with a larval period ∼10 × longer than the adult life span, is contrariwise to that of other copepods but not for animals with non‐feeding adults of both sexes. It appears that the life cycle of C. amphiodiae is pedomorphic, and probably evolved through a delay of metamorphosis regulated by developmental hormones. We attribute the dominance of the larval phase to the greater potential for survival and growth of the enterozoic parasitic stages than of the free‐living, post‐metamorphic stages. We note that among marine invertebrates, non‐feeding adults of both sexes occur exclusively in taxa with a complex life cycle, and that non‐feeding adults of both sexes are never found in taxa that have small larvae and delayed maturation. They occur only when there is a large larva that can provide the adult stage with sufficient nutrient reserves for reproduction.

Autonomy and integration in complex parasite life cycles

“…Another example is the short-lived, non-feeding stages found in a wide range of taxa [e.g. the larvae of many marine invertebrates (Thorson, 1950), adult mayflies (Brittain, 1982), the phoretic stage of astigmatid mites (Walter and Proctor, 2013), some parasitic copepods (Hendler and Dojiri, 2009); see Moran, 1994 and Benesh et al 2013 for additional references]. Some pseudophyllidean tapeworms ( Schistocephalus, Ligula and relatives) are a particularly counterintuitive case.…”