Planktonic, metamorphic, and early benthic behavior of the Chilean loco Concholepas concholepas (Muricidae, Gastropoda, Mollusca)

Late stage veliger larvae of the loco Concholepas concholepas were collected in the surface plankton in the ocean off Coquimbo, Chile (30 degree S) and transported to the laboratory for a study of settlement, metamorphosis, and behavior under simulated natural conditions. Experiments were conducted on effects of seawater turbulence and presence of natural epibiota on settlement and metamorphosis. All loco veligers captured in the neuston appeared competent. They settled on natural substrata, resorbed the velum, and then spent hours or a few days grazing on microepiphyta, during which time the protoconch became darkly pigmented. After pigmentation was completed, juvenile locos began boring barnacles and depositing the adult shell (teleconch), growing to a mean height of over 6 mm in 30 d. A two-stage induction for metamorphosis is suggested, the first involving substances from microephiphyta and the second from barnacles. Grazing on films of microorganisms alone did not trigger formation of the teleconch. The loco has evolved several alternatives that safeguard its settlement in highly wave-stressed rocky shores. It may be stimulated to metamorphose by nonspecific inducers, resist stranding during tidal changes, overcome breakage of the protoconch, and attach firmly to the substratum in turbulent seawater. Scarcity of loco veliger larvae in coastal plankton argues against using present methods as a basis for mass culture of this species.