American lobsters (Homarus americanus) utilize jet propulsion to increase the speed at which they walk along the ocean floor, according to research by scientists from St.
Francis Xavier University in Canada.
The study by Jeanette Lim and Edwin DeMont is published in a recent issue of the Journal of Experimental Biology.
Lobsters bear four pairs of pleopods (swimming legs) on their abdomen; these are paddle-like structures that the lobsters use to create a wake to propel them forwards.
The authors studied the force generated by the pleopods by emptying out the abdomen of a lobster of tissues and attaching eight miniature servomotors to operate the pleopods at the same speed as in a live lobster.
Using particle image velocimetry, they viewed and measured the flow field from the pleopods.
The authors found that the pleopod forces in the lobster are comparable to the thrust generated by well-known proficient swimmers such as bluegill sunfish (Lepomis macrochirus) and surfperch (Embiotoca jacksoni) swimming at slow to moderate speeds using their pectoral fins, and squid (Loligo pealei) using jet propulsion.
From their results, the authors hypothesize that lobster pleopods could function in a jet-assisted walking mechanism, where the pleopod jet flow assists the legs in forward propulsion.
For more information, see the paper: Lim, JL and ME DeMont (2009) Kinematics, hydrodynamics and force production of pleopods suggest jet-assisted walking in the American lobster (Homarus americanus). Journal of Experimental Biology 212, pp. 2731"2745.