sea pen

American

noun

any of several colonial coelenterates of the genus Pennatula and related genera, having the shape of a fleshy feather.

sea pen British

noun

any of various anthozoan coelenterates of the genus Pennatula and related genera, forming fleshy feather-like colonies in warm seas: order Pennatulacea

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of sea pen

First recorded in 1755–65

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

sea pen

This makes it well-adapted to hide within the white leaves of its sea pen host.

From Science Daily ● Oct. 8, 2025

A small creature called a sea pen, which helps to build reefs, could lose up to 40% of their suitable habitat by the end of the century.

From BBC ● Jun. 17, 2025

The sea pen does not currently exist, and it was not clear when Lolita would have made the move.

From Seattle Times ● Aug. 25, 2023

They demanded that SeaWorld cease capture operations within state waters; eventually, the case was settled out of court, with SeaWorld releasing the just-captured orcas from their sea pen and agreeing not to return.

From Salon ● Apr. 6, 2014

Keiko had been rescued from a theme park in Mexico and released into a sea pen, only to later die from pneumonia.

From National Geographic

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023