Zoeae ofParalithodes camtschaticawere positively phototactic to white light intensities above 1 × 1013q cm−2s−1. Negative phototaxis occurred at low (1 × 1012q cm−2s−1), but not high intensities (2.2 × 1016q cm−2s−1). Phototactic response was directly related to light intensity. Zoeae also responded to red, green and blue light. Zoeae were negatively geotactic, but geotaxis was dominated by phototaxis. Horizontal swimming speed of stage 1 zoeae <4 d old was 2.4 ± 0.1 (SE) cms−1and decreased to 1.7 ± 0.1 cm s−1in older zoeae (P<0.01). Horizontal swimming speed of stage 2 zoeae was not significantly different from ≥4 d old stage 1 zoeae. Vertical swimming speed, 1.6 ± 0.1 cm s−1, and sinking rate, 0.7 ± 0.1 cm s−1, did not change with ontogeny. King crab zoeae were positively rheotactic and maintained position in horizontal currents less than 1.4 cm s−1. Starvation reduced swimming and sinking rates and phototactic response.