|Chitons are flat mollusks with 8 segments to their shell.
They cling to rocks and use their radulas to scrape algae off the surface.
Crinoid (sea lily)
Starfish (sea star)
Underside of a starfish
Brittle stars (Ophiuroidea)
Sea urchins (Echinoidea)
Sea cucumbers (Holothuroidea)
|Sand dollars are also echinoids— they are |
basically flattened sea urchins with reduced
spines. Instead of hovering along the
surface of the sea floor as most sea urchins
do, they maneuver their bodies into the
top 1-2 cm of sediment.