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the Legacy continues…………………….
Gregory R. Mann, Ph.D. {ret.}

Sea Pen

“Ptilosarcus gurneyi”

A graceful creature of the seafloor, the Sea Pen resembles a plump, old-fashioned quill pen. Each Sea Pen is a colony of polyps (small anemone-like individuals) working together for the survival of the whole. The primary polyp loses its tentacles and becomes the stalk of the Sea Pen, with a bulb at its base—the bulb anchors the sea pen in the muddy or sandy bottom. The various secondary polyps form the sea pen’s “branches” and have specialized functions. Some polyps feed by using nematocysts to catch plankton; some polyps reproduce; and some force water in & out of canals that ventilate the colony. Sea Pen colonies are formed by several genera of the order Pennatulacea. The colony consists of a stalk formed by an organism called a primary polyp and short branches formed by secondary polyps. The stalk embedded in sand or mud, holds the colony upright. Their major predators are Nudibranchs and Sea Stars, some of which feed exclusively on Sea Pens.

During the daylight hours Sea Pens usually bury themselves into the sand and come out at night to capture plankton. Each colony is either male or female, though more are females. Colors range from dark orange to yellow and white and are often bright. Many will bioluminesce in the dark. The exposed portion of Sea Pens may grow up to 2 meters in some species. Sea Pens are marine organisms found on Atlantic & Pacific Ocean coasts in shallow to moderately deep water. Some reach a length of 2 feet (61 centimeters) or more. Although the Sea Pen is anchored into the ground, it is possible for them to pull the anchor and move to a new spot if they need to. Typically, they position themselves into a spot with a nice current that can bring them all kinds of plankton, their favorite food. 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 8 tentacles. Sea Pens glow with a bright-greenish light when stimulated.

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