Abstract
Immune mechanisms independent of any demonstrated immunoglobulin component occur among a variety of marine invertebrates and offer another challenge to the study of the evolution of vertebrate immunity from invertebrates. There is increased interest in shellfish disease, justified by the practical fact that disease has caused mass mortality of oysters, crabs, and lobsters. This paper discusses some of the biological problems in this area that need study, the recent developments in this area, and the fact that both semantic and conceptual myopia may be inhibiting progress in the area.