(^) The first visit to the Galapagos Rise vents produced sharp color photographs of
clusters of invertebrate animals of unusual size for deep-sea benthos. Particularly
prominent were vestimentiferan worms, eventually named Riftia pachyptila. The
pictures evoked curiosity and extensive research into its specific adaptations. Similar
interest has attached to many of the larger vent invertebrates, a few of which have
been studied in physiological and molecular detail. Four of those are reviewed here,
plus brief notes on some clams, but with no attempt to cover every detail known for
them, much less for the entire suite of vent faunas that currently exceeds 500 species.
Riftia pachyptila Jones, 1981
(^) All aspects of vestimentiferan biology have been reviewed by Monika Bright and
François Lallier (2010), who provide 258 of the key references. The group name
comes from the muscular collar, the vestimentum (Fig. 15.3), that surrounds worms
just posterior to the gill plume (Plate 15.1) and that expands to hold the worm at the
top of its tube with the plume exposed to the mixture of vent flow and bottom water.
Since the discovery of these worms at hydrothermal vents in 1977, over 600 papers
(and abundant popularizations) about vestimentiferans have been published. Some of
the interest extends to the related genera hosting chemosynthetic bacterial
endosymbionts in addition to Riftia: Tevnia and Oasisia living along the East Pacific
Rise, Ridgea piscesae along the Gorda Ridge System, Alaysia spp. at West Pacific
back-arc vents, and Escarpia spp., Lamellibrachia spp., and a few other species living
on sulfide-exuding cold-seeps. Osedax spp. boring into and obtaining sulfide from
whale skeletons are more distantly related. The species most “emblematic” of
hydrothermal vents has been Riftia pachyptila, still the sole species in its genus.
Because of its size, brilliant-red gill plume, and exotic biology, it has attracted a long
sequence of submarine dives supporting studies of its morphology, genetics,
physiology, symbiosis, reproduction, embryology, and ecology.
Fig. 15.3 Diagrammatic sections of Riftia pachyptila. (a) Anatomical layout. (b) Some
biochemical exchanges.
(^) (After Felbeck & Somero 1982.)