Volutamides A-E (1-5), halogenated alkaloids of amino acid origin, have been isolated from the temperate Atlantic bryozoan Amathia convoluta Lamouroux. The structures of the new compounds were determined by spectral and chemical methods. The absolute stereochemistries of volutamides B and C were established by CD measurements, while the absolute stereochemistries of volutamides D and E could not be established with confidence. Several of the volutamides deterred feeding by potential predators and were toxic toward larvae of a co-occurring hydroid, suggesting that these metabolites form the basis of an effective chemical defense. Copyright (C) 1996 Elsevier Science Ltd