(Georgia Institute of Technology, 2003-11-28)
Kicklighter, Cynthia Ellen; Kubanek, Julia; Barsby, Todd; Hay, Mark E.
Numerous studies have investigated chemical defenses among sessile species growing
on hard substrates, but few have addressed this for mobile species in soft-sediment communities. We
investigated the palatability and potential chemical defenses of 11 worm species from soft-sediment
systems in southern Florida, USA. Three species were unpalatable to the bluehead wrasse Thalassoma
bifasciatum. The polychaete Cirriformia tentaculata and the hemichordate Ptychodera bahamensis
were uniformly unpalatable. For the polychaete Eupolymnia crassicornis, the exposed tentacles were
unpalatable, but the body, which remains protected in a deeply buried tube, was palatable. These
unpalatable worms were chemically defended; extracts of C. tentaculata, P. bahamensis, and the
tentacles of E. crassicornis deterred fish feeding. For C. tentaculata, bioassay-guided fractionation
demonstrated that a mixture of 3 closely related alkylpyrrole sulfamates deterred fish at naturally
occurring concentrations (2-n-hexylpyrrole sulfamate [1.6% of worm dry mass], 2-n-heptylpyrrole
sulfamate [3.1% dry mass], and 2-n-octylpyrrole sulfamate [0.8% dry mass]). This appears to be the
first documentation of characterized natural products defending a marine worm from consumers. For
P. bahamensis and the tentacles of E. crassicornis, deterrent effects of crude extracts decomposed
before specific compounds could be identified