Ships and Shipworms: How Seafarers Adapted to Marine Wood-Boring Mollusks in the Western Atlantic, 1500-1700

• In Event: Re-envisioning Maritime History as Environmental History

Abstract

For early modern explorers, the Atlantic Ocean, with its pounding waves and devastating storms, proved a most hostile environment. One of its biggest threats came from one of its smallest organisms: the shipworm. Shipworms are tube-like marine wood-boring mollusks (cousins to clams) that bore into wood for food and shelter. Europeans knew about shipworms long before Columbus ever set sail to the New World, but as explorers and traders scattered throughout the Atlantic, they discovered that these woodborers grew larger and faster in the warmer waters of the tropical and subtropical western Atlantic. Hundreds of shipworms could perforate a ship’s hull and turn it into a leaky sieve in less than a season. Voyages across the Atlantic, then, turned into a race against time; tarrying too long could cripple a ship and kill its crew.

Seamen plying the Atlantic learned to adapt to this unforeseen biological threat. Adaptation took many forms. To better assess risks, Europeans engaged in a broad discourse on shipworm biology and ecology (which included Dutchmen, Spaniards, Englishmen, and even Native Americans); they exchanged knowledge about woodborer taxonomy, debated shipworm geography; and they pondered on which trees might resist borers. Applying this knowledge proved tricky and involved a lot of guesswork. Shipbuilders struggled to develop hull coatings and metal sheathings that would repel borers. For captains unwilling to pay high costs for unproven protectants, their only recourse was to time voyages across the Atlantic and back around the supposed breeding season of the shipworm. In these ways and others, shipworms shaped how early modern seamen negotiated marine environments throughout the Atlantic until the advent of copper sheathing in the eighteenth century. Resurrecting the lost history of shipworms adds to our understanding of the environmental history of the sea, which is only starting to come into focus.

Author

• Derek Lee Nelson, EVCC