Biology of feeding and digestion in the Talitroidea (Crustacea, Amphipoda)

Research on foods, feeding and digestion of talitrids are evaluated from the point of view of each of the biological subdiscipline (ecology, physiology, ethology, biochemistry, morphology and microbiology). The structure of the review follows the ecotype and generalist-specialist concepts as applied to talitrid species. Each talitrid ecotype is proposed to be associated with a preferred food class and mode of digestion. Thus, wrack generalists can digest many species of marine macroalgae or angiosperm plant litter in later stages of decomposition and switch digestive mechanisms from one to the other according to plant food availability. By comparison specialist ecotypes are more limited in feeding choices, such as psammophiles to micro- or macro-algae found on sandy beaches and palustrals to salt marsh plant litter. Of the 31 talitrid species included in this review for which the ecotype could be determined, 18 are from the North Atlantic coast and 13 from other parts of the world. Discovery of the physiological mechanisms of talitrid digestion is at an early stage of development and hypotheses are proposed to facilitate further research. Endosymbiotic bacteria resident in the hepatopancreas and ingested with decaying plant food are important in digestion of wrack generalist, palustral and xylophage talitrids.