The anterior end of a chemosynthetic siboglinid tubeworm,
Lamellibrachia sp., protrudes from its tube. The red “feathers” are respiratory tentacles filled with hemoglobin-containing “blood.” The white structure is called an obturaculum and functions as a trapdoor that protects the opening when the worm withdraws into its tube. Brown branched hydroid colonies grow on the tube.
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