How to be the perfect host: The physiology
of chemosynthetic invertebrate-bacterial associations
Shana Goffredi, Ph.D.
Monterey Bay Aquarium Research Institute
Wednesday, February 24, 1999
3:00 p.m.Pacific Forum
Deep-sea hydrothermal vents and cold seeps are home to a variety of invertebrate
species, many of which exist in symbiotic arrangements with sulfide-oxidizing bacteria.
Many of these invertebrates rely entirely on chemoautotrophic symbionts for nutrition,
which allows them to live in areas where phototrophic contributions are minimal. In order
to maintain successful associations with these bacteria, the invertebrates must meet many
unusual demands, normally not experienced by other metazoans. These biochemical demands
include the uptake of inorganic carbon and sulfide, as well as the elimination of
bacterial end products, including large amounts of protons and sulfate ions. Riftia
pachyptila, the most conspicuous organism living at deep-sea hydrothermal vents, is
able to overcome these demands because of its remarkable ability to control its
extracellular pH, a suite of carbon-concentrating mechanisms, and an unusual mode of
mediated sulfide uptake. In contrast, vesicomyid clams are the dominant invertebrates
living in many cold seep areas, including the Monterey Canyon. An interesting feature of
these clam communities is that the two predominant species, Calyptogena kilmeri and
C. pacifica, presumably share similar modes of existence yet appear to live in very
different chemical conditions. Physiological factors controlling their distribution within
the Monterey seep sites will be discussed. These invertebrate-bacterial associations
demonstrate a number of unique adaptations that enable them to dominate in areas largely
unavailable to other animals.
Research on these animals continues to reveal further insight into the astonishing
reality that metazoan life can thrive in some of the most hostile and primitive
environments known to science.
coupling in the equatorial Pacific during the 1997-1998 El Niņo
Last updated: December 19, 2000