1. Laboratory of Animal Physiology, Catholic University of Louvain, Place Croix du Sud 5, 1348 Louvain–la–Neuve, Belgium
2. Laboratory of Marine Biology, University of Brussels, Avenue F. D. Roosevelt 50, 1050 Bruxelles, Belgium
3. School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK