Tube feet are the many small tubular projections found most famously on the oral face of a sea star's arms, but are characteristic of the water vascular system of the echinoderm phylum which also includes sea urchins, sand dollars and sea cucumbers and many other sea creatures.
Tube feet function in locomotion, feeding and respiration. The tube feet in a sea star are arranged in grooves along the arms. They operate through hydraulic pressure. They are used to pass food to the oral mouth at the center, and can attach to surfaces. A sea star that is overturned simply turns one arm over and attaches it to a solid surface, and levers itself the right way up.
Tube feet allow these different types of animals to stick to the ocean floor and move very slowly.
Tube feet consist of two parts: ampulla and podia. Ampulla contain both circular muscles and longitudinal muscle, whereas the podia contain the latter only. Thus the podia use suction to attach to the substratum.
Famous quotes containing the words tube and/or feet:
“The last best hope of earth, two trillion dollars in debt, is spinning out of control, and all we can do is stare at a flickering cathode-ray tube as Ollie answers questions on TV while the press, resolutely irrelevant as ever, asks politicians if they have committed adultery. From V-J Day 1945 to this has been, my fellow countrymen, a perfect nightmare.”
—Gore Vidal (b. 1925)
“A good intention clothes itself with sudden power. When a god wishes to ride, any chip or pebble will bud and shoot out winged feet and serve him for a horse.”
—Ralph Waldo Emerson (18031882)