Acid secretion by the boring organ of the burrowing giant clam, Tridacna crocea
DOI | 10.1098/rsbl.2018.0047 |
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Year | 2018 |
Journal | Biology Letters |
Volume | 14 |
Number | 6 |
Pages | 20180047 |
Type | article in journal |
Language | English |
Id | 49377 |
Abstract
The giant clam Tridacna crocea, native to Indo-Pacific coral reefs, is noted for its unique ability to bore fully into coral rock and is a major agent of reef bioerosion. However, T. crocea’s mechanism of boring has remained a
mystery despite decades of research. By exploiting a new, two-dimensional pH-sensing technology and manipulating clams to press their presumptive boring tissue (the pedal mantle) against pH-sensing foils, we show that
this tissue lowers the pH of surfaces it contacts by greater than or equal to 2 pH units below seawater pH day and night. Acid secretion is likely mediated by vacuolar-type Hþ-ATPase, which we demonstrate (by immunofluorescence) is abundant in the pedal mantle outer epithelium. Our discovery of acid secretion solves this decades-old mystery and reveals that, during bioerosion, T. crocea can liberate reef constituents directly to the soluble phase, rather than producing sediment alone as earlier assumed.