Sea Pen Sealife Closeup Royalty-Free Stock Photo

Sea Pen or ptilosarcus gurneyi at aquarium in Seattle, Washington. Close up. The red star, the leather star and three types of nudibranchs prey on sea pens. When disturbed, a sea pen forces water out of the colony, making it possible for the sea pen to retreat into its bulbous foot. Sea pens are octocorals—each polyp has eight tentacles. Colorful Sea Pens Decorate Ocean Floor A nocturnal Veretillum sea pen gathers dinner with its flower-like polyps unfurled as it feeds using the eight tentacles surrounding each polyp`s mouth. Credit: Gary C. Williams, California Academy of Sciences As their name suggests, sea pens can look like writing pens, or they can resemble feathers, whips or worms. But these diverse and delicate underwater animals, which are a type of coral, are also hard to pin down: A single sea pen is both an individual and a colony.