Burrowing of the lingulid brachiopod Glottidia pyramidata: its ecologic and paleoecologic significance

Contrary to popular assumption, the pedicle of Glottidia is not its principal burrowing organ. The brachiopod props itself up with the pedicle and enters the sediment with the valves leading, anterior end first. The pedicle trails behind. Burrowing is accomplished by cyclical valve motions: rotary, sliding, and gaping movements are used. Rapid valve closure ejects water from the mantle cavity to loosen the sediment. The lateral setae convey mucus-bound sand posteriorly (upwards). X-radiography shows that the burrows are U-shaped: in a few hours, the animal reappears in feeding position with the anterior end pointing out of the sediment and the pedicle extending down into the burrow. This burrowing process explains the substrate preferences of lingulids. The thick. closely spaced setae are adapted for burrowing. The spacing between individuals is increased, suggesting competition for food.