The Effects of Desiccation on the Metabolic Rate of Earthworms (Lumbricus terres!ris)
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Research has shown that earthworms are beneficial to agriculture by creating, through egestion, the finely, enriched fragments of castings that are essential for plant growth. Their burrows increase preferential flow of water and air and form the conduits for water conduction and chemicals, decreasing run-off and helping in the maintenance of soil nutrients. These studies have examined the effects of worms and worm burrows on water in agricultural systems, yet the effects of water on earthworms has been relatively unexplored. Gas exchange by earthworms takes place by diffusion through the epidermis. For cutaneous respiration to occur, it is essential that a thin film of moisture be maintained on the respiratory surface by continuous secretion of mucus. In earthworms, the proportion of body water is always subject to change, especially when moving about on the surface of the ground, and the ability to survive these fluctuations in water content is of extreme importance for the survival of the organism. I attempted through this project to determine the effects of desiccation on the metabolic rate of earthworms. A control and an experimental, desiccated, group were acclimated to a constant temperature for one day, weighed and then placed into metabolic chambers where metabolic rates were recorded. There was no significant change in metabolic rate as desiccation increases. Thus, it seems that earthworms are capable of maintaining cutaneous blood flow and, thereby, gas exchange that sustain metabolic rate even though they become significantly desiccated.