Final answer:
Sea lilies are sessile crinoids that attach to surfaces using a stalk, while feather stars are free-moving and inhabit shallow tropical waters. Both are suspension feeders using feather-like arms to collect food.
Step-by-step explanation:
Difference between Sea Lilies and Feather Stars
Sea lilies and feather stars are both examples of Crinoidea, a class within the phylum Echinodermata. The main difference between the two is that sea lilies are sessile, anchored by a stalk, whereas feather stars are free-moving and use leglike cirri for locomotion. Both are suspension feeders and possess feather-like arms used for capturing and guiding food towards the mouth. While sea lilies primarily dwell in deep waters, feather stars are more commonly found in shallower, tropical regions.
Abundance and Habitat
Crinoids were much more abundant in ancient oceans, but today there are about 600 extant species. Crinoids, in general, are most abundantly found in deep-water habitats. However, feather stars can often be seen in shallow tropical waters at night, clinging to rocks and other surfaces.