Light as an ecological factor in the dispersal and settlement of larvae of marine bottom invertebrates

Abstract

Abstract Roughly 90,000 species of marine bottom invertebrates reproduce by pelagic larvae, thus spending the most sensitive period of their life under the influence of light. Data on their responses to light have here been brought together for larvae of 141 species. In their early pelagic stages. 82 % of these species respond positively to light and migrate to the surface layers, 12 % seem to be indifferent to light. and 6 % respond negatively to light and continue to do so during their whole pelagic life. In their later and oldest pelagic stages most of the initially photopositive larvae will turn over to photonegativity, seeking down to deeper lying bottoms. but larvae of many intertidal species will remain photopositive till they stop swimming, thus sticking to the surface layers where they can get into contact with intertidal localities. Larvae of such groups which already in their pelagic phase live in symbiosis with zooxanthellae, do not seem to have another pattern of light-response than larvae of...