Orange Sea Pen

Ptilosarcus gurneyi

Orange Sea Pen

Ptilosarcus gurneyi

Other Common Names
Fleshy Sea Pen
Gurney’s Sea Pen

Sandy Coast

Other Common Names

Fleshy Sea Pen
Gurney’s Sea Pen

At the Aquarium

Sandy Coast

Appearance

The orange sea pen grows to be up to 18 in. tall and 4 in. wide. Much like the quill pens they are named after, the sea pen has a series of straight branches that come from a central line. Orange sea pens can retract their branches into their base to hide from predators.

Habitat

Sandy areas, subtidal zone to waters as deep as 100 ft.

Diet

Zooplankton

Life History

Orange sea pens breed between March and April. The eggs drift along until they reach their next life stage as planula larvae. This planula settles to the sea floor and becomes a tiny polyp. Sea pens are closely related to the sea anemone and a sea pen polyp looks like a miniature sea anemone. The orange sea pen polyp will clone itself over and over again to form a colony of polyps, which comprise the adult sea pen that people can see on-habitat at the Aquarium.

IUCN Status

Ecosystem & Cultural Importance

Since orange sea pens eat microscopic plankton, they allow nutrition to travel up the food chain. When these sea pens are eaten by sea slugs and leather stars and those are then eaten by their predators, it allows the nutrition from microscopic plankton to reach the upper range of the food web.

Central California to British Columbia

Can be found in deeper waters offshore.

The orange sea pen is eaten by a few species of sea slugs and leather stars. An orange sea pen can tell what species of sea star is touching it, and will retract its body into its base if the offender is a leather star.
Orange sea pens begin their lives as a singular polyp. This polyp clones itself again and again until it becomes a large colony which works together to be what we call a single sea pen.
When the orange sea pen is disturbed it can glow greenish-blue.

Citations & Other Resources

Lambert, J. 1999. Ptilosarcus gurneyi. Animal Diversity Web. University of Michigan Museum of Zoology. https://animaldiversity.org/accounts/Ptilosarcus_gurneyi/
Burgess D., A. Eagleston. 2017. The Orange Sea Pen. Encyclopedia of Puget Sound. https://www.eopugetsound.org/articles/orange-sea-pen
Weightman J. O., D. J. Arsenault. 2002.Predator classification by the sea pen Ptilosarcus gurneyi (Cnidaria): role of waterborne chemical cues and physical contact with predatory sea stars. Canadian Journal of Zoology. 80(1): 185-190.

Orange Sea Pen

Orange Sea Pen

Other Common Names

At the Aquarium

Appearance

Habitat

Diet

Life History

IUCN Status

Ecosystem & Cultural Importance

Citations & Other Resources

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