Christmas tree worms have eyes that breathe, gills that see
Improvised eyes help the marine invertebrates sense danger
By Susan Milius
Christmas tree worms have eyes “in a really silly place,” says Michael Bok. Which is part of their charm.
This widespread marine worm (Spirobranchus giganteus) gets its holiday nickname from its gills: a wildly colored pair of tapering, feathery spires that protrude from the top of the worm’s buried retreat like ornamental trees. Bok, of Lund University in Sweden, says he has seen worm gills in red, orange, blue, yellow — even stripes.
When a shadow looms, the Christmas tree gills drop down into the protective tube where the rest of the worm hides. Yet the eyes that check for scary things lie beneath the branches like forgotten presents. To see the bright orange compound eyes, “you have to kind of sneak up on them and look at them from the right angle,” Bok says.