Interior remodeling oftheshell byagastropod mollusc (biomineralization/Conus/shell dissolution)

AstheConus shell grows byspiraling ofthe outer liparound theaxis, profound internal shell dissolution thins thewalls oftheprotected penultimate whorl from several millimeters to<50&m. Shell material isadded totheinside of thespire andtheanterior part ofthecolumella. Theresulting shell hasauniformly thick last whorl andthickened spire that enhance defense against crushing predators andagreatly ex- panded interior living space fortheanimal. Themolluscan shell hasgained prominence inrecent years as anespecially favorable system fortheanalysis ofbiominerali- zation processes (1-4). Muchless attention hasbeen paid toshell dissolution, acontinuing, permanent, andprofound process that alters exterior andinterior surfaces oftheshell incertain pro- sobranch gastropods (5-7). Inthegenus Conus, dissolution of theinternal walls oftheshell isparticularly striking while shell material isadded fromwithin tothicken regions oftheshell somedistance fromits growing edge. Although these renova- tions have notbeenstudied previously, theresulting very thin inner wall structure haslong beenknown(8) andwasused as theprimary character separating subfamilies oftheConidae inanearly classification (9). Inthis study weaddressed thefollowing questions: (i) What regions andlayers oftheshell areinvolved indissolution and thickening? (ii) Oftheshell material deposited bytheanimal during its life, howmuchislater dissolved? (iii) Howmuchof theanimal's living space within theshell does dissolution pro- duce? (iv) Whatistheadaptive significance ofinterior shell remodeling?