Journal of the Marine Biological Association of the United Kingdom

Research Article

Adaptations for living deep: a new bathypelagic doliolid, from the eastern North Pacific

Bruce H.  Robison a1c1, Kevin A.  Raskoff a2 and Rob E.  Sherlock a1
a1 Monterey Bay Aquarium Research Institute (MBARI), Moss Landing, CA, 95039, USA
a2 California State University, Monterey Bay, Seaside, CA, 93955, USA

Article author query
robison bh   [PubMed][Google Scholar] 
raskoff ka   [PubMed][Google Scholar] 
sherlock re   [PubMed][Google Scholar] 


Adapting to the bathypelagic habitat imposes serious challenges for taxa that originate in shallower depths. We describe a new doliolid that has successfully made the transition into deep water. Nine specimens of Pseudusa bostigrinus have been found at depths between 1164 and 1890 m in three distinct regions of the eastern North Pacific. This new thaliacean has exchanged the typical doliolid body plan for one resembling a craspedote hydromedusa. This adaptation allows it to collect sinking particles by simply directing its large buccal opening upward. The development of a hydromedusa-like velum allows it to trap zooplankton prey and to propel itself with considerable force and control. While carnivory is not unknown in tunicates, this is the first report of a carnivorous doliolid. The endostyle of P. bostigrinus is greatly reduced, there are no ciliated bands, and there is no spiral gland; all evidence that mucus feeding filters have been abandoned by this species. Anatomy, diet, behaviour, and habitat distinguish this doliolid from all others described to date.

(Received November 2 2004)
(Accepted February 28 2005)

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