GENERAL HISTOLOGY

Detailed explanation-1: -Unique from other extant echinoderm classes, crinoids feed primarily by filter feeding. To feed, crinoids use their stalk, or column, to elevate the crown (i.e., cup with vital organs, and feather-like arms) into the water column.

Detailed explanation-2: -The Class Crinoidea contains many brightly-colored echinoderms known as sea lilies and feather stars. Sea lilies are permanently attached to the substrate by a stalk, while feather stars (shown above) are swimming or crawling animals that can attach to the substrate using a ring of claw-like projections.

Detailed explanation-3: -Although they may appear very different, echinoderms all have two major defining characteristics that set them apart from all other animals: a water vascular system and five-sided radial symmetry.

Detailed explanation-4: -The sea lilies are considered “stalked” crinoids because they have an extended stalk that attaches to solid substrates on the ocean floor. The sea lilies are the only existing echinoderms that live attached to a solid surface.