Monterey Bay Aquarium Research Institute
Midwater ecology
Doliolula equus, a new mesopelagic doliolid

Ecological substrate in midwater: Doliolula equus, a new, mesopelagic tunicate

Bruce H. Robison1, Kevin A. Raskoff2 and Rob E. Sherlock1

1Monterey Bay Aquarium Research Institute, Moss Landing, CA, 95039, USA

2California State University, Monterey Bay, Seaside, CA, 93955, USA 


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  • Abstract:  In the pelagic habitat, the bodies of resident animals provide much of the ecological substrate available for other organisms to attach, find shelter, and seek food. In Monterey Bay, California, the doliolid Doliolula equus provides substrate for multiple symbionts. These include a mutualist hydroid, commensal ciliates, and a parasitic amphipod. We describe this new doliolid based on in situ observations from a remotely operated vehicle, and from the laboratory examinations of 43 colonies comprising hundreds of living, individual blastozooids. Doliolula equus differs from other members of the suborder Doliopsidina in the shape of its body, the length and configuration of its third muscle band, the size of its buccal siphon, and the position of the spiral gland. The new doliolid was found principally at depths between 300 and 400 m. This species is bioluminescent, hermaphroditic, and about one zooid in ten is peppered with orange pigment spots. A variety of other, obviously related, yet undescribed forms have been observed in the eastern Pacific.
  • Future Studies:  We will continue to study the doliolids that live in the Monterey Bay. We have only begun to learn more about their associated fauna and are focusing initially on the Phyllopharyngiid-like ciliates that we call 'discs'.
Last updated: Feb. 05, 2009