DEMINERALIZATION MECHANISM OF BORING GASTROPODS 7o 



MorpJi()h)<iic(il Chavacicristics of SlicU TicaiccI 

 Artificidlbj hij Chemical Agents 



As an aid in interpreting the etching patterns produced by ABOs 

 we attempted to determine whether comparable alterations could 

 be produced artificially through the treatment of (fl) nacreous cal- 

 cite shell surface (C. virginica) and (b) nacreous aragonite shell 

 surface (M. fiilvescens) with (1) agents which primarily attack 

 the mineral portion, such as organic or inorganic acids, and a se- 

 questering agent, versene, (2) agents which attack selectively the 

 organic component, such as ethylenediamine, and ( 3 ) agents which 

 attack both the organic and inorganic constituents, such as strong 

 alkalies. Accordingly shell surfaces were immersed in ( 1 ) HCl or 

 lactic acid and sodium versenate, (2) ethylenediamine, and (3) 

 KOH. 



Some typical examples of the surface effects of these various 

 agents, as compared with that of the secretion from the ABO (Figs. 

 12 to 15), are shown in Figs. 26 to 31 for calcitic and aragonitic 

 shells. Although none of the treatments resulted in damage exactly 

 like that obser\ ed in the shells exposed to ABO activity ( Figs. 12 to 

 15), disfiguration of the acid-etched (Figs. 26 and 27) and versene- 

 treated (Figs. 28 and 29) specimens bore the closest resemblance. 

 Particularly striking was the comparability of damage to the crystals 

 themselves, such as pitting and serrated edges, caused by HCl and 

 versene (Figs. 32 to 37) and by the ABO secretion (Figs. 20 to 25). 



Figs. 16 and 17. Optical (Fig. 16, X 50) and electron (Fig. 17, X 6000) 

 micrographs showing the etching produced by an ABO from Urosalpinx cinerea 

 follijcnsis which was phiced in a piece of minute plastic tubing against the 

 nacreous surface of the shell of Spisiila solidissima. The sharp impression of the 

 outer edge of the plastic tube is clearly evident where it sank into shell ma- 

 terial weakened by the ABO secretion. A lightly damaged area is illustrated 

 in the electron micrograph. 



Figs. 18 and 19. Optical (Fig. 18, X 50) and electron (Fig. 19, X 6000) 

 micrographs showing the etching produced bv a drop of the homogenate made 

 from the ABOs of U. c. foUyensis, diluted 50 times and placed on the nacreous 

 surface of the shell of S. soUdis.sitna. A very heavily etched region is shown 

 in the electron micrograph. 



