The 27 Best Deep-Sea Species: #7 Predatory Tunicates

#7: Megalodicopia hians (Phylum: Chordata, Class: Ascidiacea , Order: Phlebobranchia, Family: Octacnemidae)

This tunicate post is dedicated to Miriam. Those invertebrate sacs are one of our closest living invertebrate
relatives.  Let’s hear it for notochords and pharyngeal slits!

Most sea squirts are harmless little buggers that filter plankton out of the water column.  Water comes in through one siphon and out another (the in- and excurrent siphons). One group of sea squirts stands out-the family Octacnemidae.  The several genera in family have hypertrophied oral siphons (that’s just fun to say-hypertrophied oral siphon) that form two large lips creating an oral hood.  Anchored to the bottom, the wait until an unsuspecting small crustacean swims by. Then WAMM the large lips clamp close and its bye bye little arthropod.  Think Venus Fly trap but marine, deeper (200m to 3800m), and cooler.

Megalodicopia are also gender benders with both male and female bits.  Yeah simultaneous hermaphrodites!  If an individual cannot get any loving from a nearby predatory tunicate it gets busy with itself.

Feeding video here

Dr. M (1729 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, a National Science Foundation supported initiative. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web. His forthcoming book, Science of the South (, connects cultural icons of South such as pecan pie with the science behind them.

5 comments on “The 27 Best Deep-Sea Species: #7 Predatory Tunicates
  1. Gotta be careful – those tunicates, they will cut you!

    (fyi, blog back in a few – transitioning out of the davis womb…)

  2. Yay Dr. Byrnes! Trust me I know how difficult it is to be outside the protective cocoon of the UC-Davis campus. Its amazing the world outside of UCD can function at all.

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