The sunflower star, Pycnapodia helianthoides , has two sizes of pedicellaria, but it is not known how the two provide different roles. Each papula is a sac that protrudes out through holes in the skeleton. Its contents are thus connected to the body cavity of the sea star. Researchers have discovered that sea stars can actually take dissolved organic nutrients out of sea water under some circumstances, and so they can gain some of their nutrition by slurping in molecules from the very dilute organnic soup in which they live. This material may be copied for use in student classroom projects and reports.
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