Abstract

Parental care behavior is reported from different crustacean taxa and environments but at present no general pattern has been recognized. The major goal of this review is to synthesize the present knowledge about parental care in crustaceans and to identify whether common traits can be identified. Crustaceans as different as synalpheid shrimp, spider crabs, crayfish, isopods, tanaids and amphipods engage in parental care but no specific morphological traits were connected with this reproductive behavior. Both iteroparous and semelparous crustaceans have been found to engage in parental care. Peracarid species that provide extended parental care for their offspring produce similar numbers of eggs as those peracarids that provide no post-marsupial care. Decapod species with extended parental care (synalpheid shrimp, some brachyuran crabs, many crayfish), produce relatively small numbers of eggs and care for individual broods for relatively long time periods. Highly motile species often carry their offspring on their body or in 'mobile homes', while sedentary species usually host their offspring in/on their dwellings (e.g. tubes and burrows). Crustaceans that carry their offspring hosted only one age cohort of juveniles on their body but those that provided for offspring in/on a dwelling could host up to three subsequent age cohorts of juveniles simultaneously. Food sharing with offspring has been observed in both motile and sedentary species. The most advanced form of parental care is found in terrestrial crustaceans where parents forage in the vicinity of an offspring cradle to which they return food items to feed their young. In general, the high diversity of crustaceans with extended parental care suggests that this reproductive behavior has evolved independently in a variety of crustacean taxa under a variety of environmental conditions. Several examples of convergent evolution of the same form of parental care support this assumption. While the potential for parental care may be high in crustaceans, the occurrence of advanced social behavior probably is limited to crustaceans with an offspring cradle as is indicated by the exclusive finding of return-foraging and multiple juvenile age cohorts among the latter species. Crustaceans offer a unique opportunity to study the evolution of extended parental care since species from a variety of both aquatic and terrestrial environments engage in this reproductive strategy.