What happened here?? He answers the mystery at his blog, Chronicles of Zostera, but I’ll give you a hint: it may have something to do with an arms race of sorts (read more about that here, here, or here).
Time it took for four crab species to break into and eat Littorina sitkana snails, grouped by snail size. The numbers above each bar represent prey biomass (mg) over total handling time (minutes) - this measure represents "prey profitability", like how much bang the crabs got for their buck. Crab claw morphology is pictured below each species name. Scale bar is 10 mm.
Adapted from Yamada and Boulding (1998)