ABSTRACT
Settlement and metamorphosis constitute, arguably, the most complex period in the life history of marine invertebrate larvae. Chemical cues that induce settlement provide a mechanism to assure larval recruitment into a suitable habitat. This chapter provides a brief overview of chemical cues that induce or inhibit settlement of marine invertebrate larvae. Settlement and metamorphosis have been further defined as behavioral and physiological phases, respectively. Environmental factors that influence larval settlement fall into physical, biological, and chemical categories. Physical factors that might have an impact on larvae in the water column include water flow, light, gravity, temperature, salinity, and pressure. The presence of a microbial blofilm has been previously recognized as requisite to the successful settlement and metamorphosis of many fouling organisms. Enhanced settlement of a heterospecific onto another species is termed associative settlement and there are many examples of this phenomenon in the marine environment.
