title for learn-about sections for chitons in A SNAIL'S ODYSSEY
  Feeding, growth, & shell repair
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Shell repair

  Topics in this section of the ODYSSEY include shell repair, considered here, and RADULA & FEEDING, DIETS, and GROWTH considered in other sections.
Research study 1

composite photos of shell plates of 3 west-coast chitonsphotographs of shell plates of a gumboot chiton Cryptochiton stelleri undergoing repairExamination of skeletal plates of several species of chitons at Hopkings Marine Station, Pacific Grove, California reveal that those of Katharina tunicata and Mopalia hindsii are quite sturdy, comprise about 20% of live mass, and are broken in about 20% of specimens examined.  In comparison, those of gumboot chitons Cryptochiton stelleri comprise only about 7% of live mass, and most specimens examined show breaks in one or more of the skeletal plates.  Repair of a crack begins with secretion of a membrane that encloses the crack on both sides of the plate.  Within the membrane fine granules of calcium salts accumulate, followed by secretion of calcium-carbonate crystals.  The crystals are embedded in the membrane, leaving a ridge over the crack and often a space between the old and new shell materials.  The repair is thus weak, and is easily broken along the old crack line.  Repair is slow, often taking several months for a crack to be mended.  Tucker & Giese 1959 Biol Bull 116: 318.