In Evolutionary origins of sensation in metazoans: functional evidence for a new sensory organ in sponges, Danielle A Ludeman and her team at the University of Alberta document the heretofore unsuspected phenomenon of sneezing in freshwater sponges. When these sponges are stimulated with damaging sediment, they close their chimneys and inflate themselves to bursting, then abruptly "sneeze" out the irritants -- a process that unfolds very slowly (documented above in timelapse). I found out about this thanks to a fascinating interview (MP3) with the researcher on CBC Radio's As It Happens.

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