Details
Ptilosarcus gurneyi
The orange sea pen is a colonial cnidarian shaped like a feather quill. Anchored in soft sediment, it catches suspended food with rows of tiny polyps.
Map: Ecoregions 2017 © RESOLVE (CC BY 4.0) · Natural Earth (PD)
It lives on Pacific muddy and sandy bottoms, bays, and deeper coastal seafloors. Soft sediment and steady currents are important.
Height 15-50 cm; weight 20-200 g. Orange side branches extend from a central stalk, each lined with small polyps. A fleshy lower peduncle anchors the colony in the bottom.
Cathemeral and colonial, it opens polyps when currents carry food. When disturbed it can contract and withdraw toward the sediment.
A filter-feeder, it captures plankton and organic particles with tentacled polyps. The colony presents its branches into the flow to gather food efficiently.
Adults release eggs and sperm into the water, while the colony also grows by adding polyps. Larvae drift before settling into soft bottom.
It is listed as Least Concern. Its upright soft-bottom form can be vulnerable to trawling and other seafloor disturbance.
