Castle Walls

Through a microscope, this corrugated coral looks like a castle wall. Rather than repel invaders, the coral will catch and eat any of the little arrowhead-shaped crustaceans that get caught on the coral’s thin white digestive “mesenterial” filaments. This coral was collected in Panama during a field course for MIT-WHOI Joint Program students taught by biologists Jesús Pineda and Ann Tarrant. (Photo by Liz Drenkard, Woods Hole Oceanographic Institution)