Digging mechanisms and substrate preferences of shovel nosed lobsters, Ibacus peronii (Decapoda: Scyllaridae)

Abstract

Digging is a distinct form of locomotion that poses different mechanical problems than other locomotor modes that are commonly used by crustaceans, e.g., walking, swimming. I examined the mechanisms of digging by shovel nosed lobsters (Ibacus peronii), which spend most of the day underneath sand. Ibacus peronii were videotaped while digging. Ibacus peronii use a "wedge" strategy to submerge into sand. An individual penetrates the sand with the walking legs, then extends the abdomen to push sand backwards, then flexes the abdomen while pushing backward with the legs, which slowly drives the body into the sand. This basic sequence repeats for several minutes. Digging often ends with a short series of tailflips. Digging by "wedging" is substantially different from previously described mechanisms in more specialized digging species. When presented with a choice of substrates, I. peronii preferred to dig in sand over shell grit, but individuals showed no preference for different types of sand.