The sea pen is a quill-like animal that lives in tropical waters. It is related to the sea anemones and jellyfish. They grow up to be 2 meters long.

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The body type is a polyp. Their skeleton is made of millions of tiny animals. They have these tentacle organs that are used to feel and capture its prey. Each tentacle contains nematocyst cells, which poisons prey and paralyzes them. Depending on the ocean’s current, help the sea pen to capture plankton. The common predators are sea slugs and sea stars. The sea pen can trigger this green glow when it had been bothered, called a bioluminescence.

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They reproduce sexually and also by asexual fission. The larvae, called planulae, drift along the water’s current for a week. After a week, it will settle somewhere. They can live up to more than 100 years.

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Sea pens live big colonies, so the population is also they are commonly found in sandy or loose gravel areas. They use their peduncles to grasp on or anchor to bury themselves in the deep parts of the water. They aren’t covered fully, but the “feather” part sticks out. These animals are likely to be found less than 10 meters depth.

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Of all the research I’ve done, sea pens seem pretty amazing. I haven’t found many specific articles on this type of sea pen.  I wonder why not many people don’t know what a sea pen is. (Maybe its because they mistook them as sea anemones) What really stood out to me was how they make a green light as a defense.

 

Author: Erryn F

Published: 02/2013

 

Sources:

http://www.advancedaquarist.com. Rob Toonen, October 2003

http://www.marinespecies.org. Williams, G. (2012). Pennatula aculeata Danielssen, 1860.

Grassie J., “Distribution, behavior and abundance of sea pens, Pennatula aculetata, in the Gulf of Marine”, Marine Biology, September 1990, Volume 107, Issue 3, pp 463-469

 

Picture Source: http://content65.eol.org/content/2011/06/28/04/77125_260_190.jpg