Files in this Data Supplement:

• Supplemental Figure S1 -

  Fig. S1. Nereis succinea males (two animals on the left) and a female (animal on the right). These are representative animals. Although the female is much larger than the two males in this picture, both sexes can vary in size over a broad range, as previously described (Ahrens et al., 2001; Ram and Hardege, 2005).

  References

  Ahrens, J. J., Hertz, J., Lamoureux, E. M., Lopez, G. R., McElroy, A. E. and Brownawell, B. J. (2001). The effect of body size on digestive chemistry and absorption efficiencies of food and sediment-bound organic contaminants in Nereis succinea (Polychaeta). J. Exp. Mar. Biol. Ecol. 263, 185-209.

  Ram, J. L. and Hardege, J. D. (2005). Nereis succinea nuptial behavior: Does size matter? Invert. Reprod. Dev. 48, 89-94.

• Movie 1 -

  Movie. 1. Response of a male N. succinea to a moderate concentration of CSSG. The images in Fig. 4 of the paper show the swim track of the animal in this video, plotted every 0.2 s. CSSG in the syringe was 10⁻⁶ mol l⁻¹, yielding a trail concentration <10⁻⁷ mol l⁻¹. While the drawings show only the position of the original CSSG trail (identified by the yellowish fluorescent dye), the video clearly illustrates the dispersion of the chemical as the worm swims through it. The video illustrates first, the typical ‘wall-swimming’ behavior prior to encountering CSSG; next, CSSG initially stimulates turning in small circles; subsequently, larger circles result as the worm encounters more dilute dispersed CSSG, and then finally, the worm swims away.