AB 12:157-164 (2011)  -  DOI: https://doi.org/10.3354/ab00326

ABSTRACT: The ecology of sea stars appears to be related to their locomotive abilities. This relationship was studied for the sea stars Acanthaster planci, Archaster typicus, Linckia laevigata, and Protoreaster nodosus in the coastal waters of Samal Island, the Philippines between May and July 2008. In order to avoid the sensory interruptions that sea stars exhibit when moving across natural substrate, a tarpaulin (2 × 2 m) was placed on the seafloor to create a uniform habitat. Mean (±SD) locomotion rate of Archaster typicus was 45.8 ± 17.0 cm min^–1 but increased with mean radius (R). Locomotion rate increased from 17.8 to 72.2 cm min^–1 for specimens with R of 1 and 5 cm respectively. Mean locomotion rate of L. laevigata, P. nodosus, and Acanthaster planci was 8.1 ± 1.9, 18.8 ± 3.9, and 35.3 ± 10.0 cm min^–1 respectively, and was not related to R. Maximum speed of Archaster typicus was 76.0 ± 31.9 cm min^–1 and also increased with R. Maximum speed of L. laevigata, P. nodosus, and Acanthaster planci was 10.6 ± 2.7, 27.7 ± 7.5, and 50.9 ± 14.0 cm min^–1 respectively. An inter-specific comparison of locomotion rates using the number of body moves per minute suggests that the effect of body size partially overrules morphological and behavioral adaptations. The movement patterns of Acanthaster planci, L. laevigata, and P. nodosus were highly directional (ratio of displacement to total distance traveled [D:W_all] ≥ 0.86), whereas Archaster typicus displayed a more random movement pattern (D:W_all = 0.51). Water-current direction did not affect movement directions of the 4 species.

KEY WORDS: Acanthaster planci · Archaster typicus · Davao Gulf · Linckia laevigata · Protoreaster nodosus · Starfish · Speed