Data for: Reduced tenacity during “high-speed” territorial encounters in the intertidal owl limpet, Lottia gigantea: Agonistic escalation increases risk of wash-off.

Speed is in cm per min. Animals showing Continued Foraging assigned speed of 0.2 cm per min (see Wright 1982) Response. 0-Continued Foraging: Subject moves < 1 shell length in 90 s, or turns less than 90 degrees in 90s; Cephalic tentacles visible throughout 90s. 1-Retreat behavior: Subject turns more than 90 degrees away from bait limpet, and moves > 1 shell length during 90s test period. 2-Territorial behavior: Subject accelerates toward bait limpet, moving > than one shell length during 90s test period.

Sl- Shell length in mm. Tenacity-Newtons required to remove subject from substratum divided by its aperture area. ApArea- Limpet aperture area, calculated from Shell Length (see Materials and Methods)