The Functional Morphology of Starfish Tube Feet: The Role of a Crossed-Fiber Helical Array in Movement

• DOI: 10.2307/1542085
• Publication Date: 2007-01-23T05:26:13Z
• Authors: R. S. McCurley; W. M. Kier
• Keywords: Dense connective tissue

The morphology and mechanics of the tube feet, ampullae, lateral radial canals water vascular systems Luidia clathrata Astropecten articulatus (Echinodermata, Asteroidea) were analyzed. Histological methods, based on embedding in both paraffin glycol methacrylate, used to document arrangement muscle connective tissue. foot wall includes longitudinal muscles tissue fibers, latter arranged a crossed-fiber helical array, with fiber angle about 67{deg} elongated feet. No evidence was found for circular rings reported earlier studies; appearance is probably an artifact folding. ampullae are bilobed include circumferentially fibers aligned 90{deg} muscle. short equipped oneway flap valves similar those described other echinoderms. canal thin-walled, nonmuscular, enclosed ossicles ambulacrum. Frame-by-frame video analysis intact animals "windows" cut arm movements feet ampullae. previously suggested role protracting protract antagonize musculature. allows protraction prevents dilation limits elongation