Data-driven frame-by-frame analysis of surface swimming and terrestrial walking in the coastal beetle Phaleria atriceps

Surface swimming in the coastal beetle Phaleria atriceps shows significantly longer leg movement periods than terrestrial walking across all six legs, at 1,000 frames/s video resolution.

• Why it matters: Inter-leg coordination shifts with environmental conditions, but coastal insects at the land–water boundary remain understudied for how coordination changes between walking and swimming.
• What they did: High-speed video tracked six leg tips plus anterior and posterior body landmarks in 17 swimmers and 10 walkers using DeepLabCut, estimating leg movement periods from sinusoidal fits and computing inter-leg phase relationships for all 15 leg pairs.
• The result: Both locomotor modes show six-leg phase relationships broadly consistent with an alternating tripod pattern, while surface swimming differs in relative phase for L1-L2, L1-R2, and R1-R2.