Wood borers are highly specialised animals which penetrate wooden structures such as boats, wharves, jetties, driftwood and even living mangrove trees. Many can digest the wood owing to cellulose-digesting bacteria or protozoa living in their guts. Only a few species can actually produce their own cellulose-digesting enzymes (cellulases).
These are actually bivalves, the body being worm-like and protected within a calcium-lined tunnel. At the posterior end, the siphons stick out of the wood at high tide and have two calcium plugs (pallets) to seal the entrance of the tunnel at low tide. At the front end, the original shell valves are used to grind away the wood. In the days when wooden ships were important, shipworms were major pests.
These bivalves drill holes into wood, usually at very high tidal levels. They can cause extensive damage to structures like floating fish farms. They drill through mechanical action, using the two shell valves as abrasive surfaces. (Length 1-2cm)
Wood-boring isopods drill holes by mechanically scraping their way in. It is not certain if they actually feed on the wood or are detrital/filter feeders. Many of the species also drill into soft rock. They often concentrate in great numbers, giving the wood a honeycombed appearance. (Length 0.5-1 cm).
From A Guide to Seashore Life by Dr Leo W H Tan and Peter K L Ng
Published by the Singapore Science Centre and sponsored by BP
@Raffles Museum of Biodiversity Research and Singapore Science Centre