Marine Biology

Mollusca

The teredinids are commonly called as ship worm, which have world-wide distribution.These are the most destructive forms of borers of all the marine borers. The group includes several species of Teredo and several species of Bankia, which are especially damaging. All the genera of this tredinids are borers except Kuphus. Important genera include Teredo, Lyrodus, Bankia and Nausitora.

These mollusks are readily distinguishable on close observation but are all very similar in several respects. In the early stages of their life, they are minute, free swimming organisms. Upon finding suitable substratum of wood for lodgment, they quickly develop into a new form and bury themselves in the wood. A pair of boring shells on the head grows rapidly in size as the boring progresses, while the tail part or siphon remains at the original entrance. Thus, the animal grows in length and diameter within the wood but remains a prisoner in its burrow, which it lines with a shell like deposit. It lives on the wood borings and the organic matter extracted from the sea water that is continuously being pumped through its system. The entrance holes never grow large, and the interior of wood may be completely honeycombed and ruined while the surface shows only slight perforations like pin holes. When present in great numbers, shipworms grow only a few centimeters before the wood is so completely occupied that growth is stopped. However, when not crowded, they can grow to lengths of 0.3 to 1.2 m (1 to 4 ft) depending on the species.