On a recent dive at Anton Dohrn Seamount, our ROV (remotely operated vehicle) met its match! One large remotely operated vehicle, versus a tiny little deep-sea sea pen! Can the ROV arm, grab the sea pen? Watch what happens!
Sea pens are related to corals and are from the order “Pennatulacea”. Many sea pens, like this one, live in soft sediments, and in the deep sea they can be found in huge aggregations often with cup corals (Caryophillidae) and other burrowing animals nearby.
They are colonial organisms formed of specialised polyps. The feeding polyps look like anemones and are all attached to a central stalk polyp which extends into an anchoring peduncle section. Inside the central column is a rigid axial rod of calcium carbonate which, in these sediment dwelling sea pens, can be retracted down into the peduncle by an expulsion of water when they get disturbed. They are mostly sessile but can usually ‘uproot’ if neccesary.
In spite of all this, sea pens are still vulnerable to destruction by humans, especially by trawling where the net scrapes the surface of the sediment away. Because of this, aggregations of sea pens form a Vulnerable Marine Ecoystem (VME) and are a target for marine conservation efforts.
Recorded on the NERC funded deep links project cruise (@_deeplinks, https://deeplinksproject.wordpress.com/) JC136 aboard the RRS James Cook using ISIS ROV, in May 2016. Anton Dohrn Seamount, NE Atlantic.