Crinoids are and have been marine animals throughout geologic history. The word and meaning is derived from ancient Greek meaning “Sea Lilies”. They lived in shallow water and in the great depths of the oceans as they do today. The earliest known fossil group of crinoids dates back to the Ordovician Period approximately 330 million years ago.
Compared to today there are only a couple of hundred modern crinoid forms compared to the fossil record. The fossil record has demonstrated that throughout the Paleozoic Era and in various parts of the world, sea lilies were in great abundance as well as having numerous individuals.
The majority of crinoid species living today as well as those in the fossil record have been and are free-swimming however restricted by their design. Most larval species drift along with the current until nature supplies them with an adequate landing place for them to take hold. Crinoids existed in both shallow water and great depths as they do today.
The fossil record has shown some crinoid species reached lengths of more than 3 feet in length. In their adult form they would attach themselves to the sea bottom by a stalk and feather out for their food gathering arms much like the barnacles of today. Crinoids typically have a stem or foot used to attach themselves to a substrate usually on the bottom of a waterway or on a floating object. Similar to the barnacles of today, Crinoids were filter feeders extending their feathery like arms to filter out food morsels drifting past them in the current.
The crinoids underwent two periods of mass extinction one in the Ordovician Period and the other during the great Permian Extinction. The long geological trials and tribulations of these filter-feeding Crinoids have ultimately demonstrated how well suited and adaptive these creatures are throughout the Geologic Record and no doubt will continue long after the human race has found a way to survive beyond their technology.