Published online by Cambridge University Press: 21 July 2017
Stalked crinoids (sea lilies) are not extinct, but are restricted to depths below 100 m and comprise over 80 living species. Over the past 20 years, a wide range of new information on the biology of stalked crinoids has been acquired from deep-sea photography and submersible studies. Taphonomic studies show that stalked crinoids can disarticulate and undergo breakage and abrasion without significant transportation, although crinoids can survive the rigors of transportation without damage if decay has not weakened connective tissues. Because stalks can remain articulated longer than crowns, the occurrence of articulated fossil crinoid stalks should not be interpreted as proof of rapid burial. Stalked crinoids are passive suspension feeders forming filtration fans oriented normal to bottom currents of low velocity. Mutable collagenous tissues comprising the ligaments of stalk, cirri, and arms are significant in providing variable stiffness that enables stalked crinoids to maintain elevation of the stalk and the filtration fan feeding posture. Regenerated arms and stalks lacking crowns suggest that stalked crinoids are subject to predation by fish in deep water, although predation pressure is likely lower than in shallow water.