<p>What's a nudibranch, anyway? These soft-bodied mollusks are sometimes known as sea slugs. "Nudibranch" means "naked gills" -- those colorful "feathers" on the back of this hermissenda nudibranch actually help it breathe as it explores the rocky reef of Channel Islands National Marine Sanctuary. 
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Photo Credit: Claire Fackler/NOAA
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/44124469278@N01">National Marine Sanctuaries</a>
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