The exploitation of populations: Utilisation of marine invertebrates

[First paragraph...]
The utilisation of marine invertebrates extends from prehistoric nomad times through all levels of communal development to our present civilisation. The invertebrates have provided hard parts such as shells for tools, ornaments, symbols, a source of lime, jewellery, dress, weapons, fibres for cloth, dyes, and soft-parts for food. We retain today more of these usages than we have abandoned, and in some cases increased our utilisation in proportions greater than the increase in population. The requirement for commercial sponge has not extended and only a few hundred tons are now landed each year but the demand for ornamental corals is in the order of 4,000,000 pounds and more each year, while the demand for pearls is unsatisfied even with the tremendous production from Japan's pearl culture development.