June, 1999 
SCAMIT Newsletter 
Vol. 18, No. 2 
and the guard station at the rear of the building 
(as usual). There will be a second July meeting 
on 12 July to continue discussion of B’98 
related polychaete problems. 
NEW LITERATURE 
In honor of the cnidarian subject of our last 
meeting, the literature presented there (and 
here) concentrates on that phylum. 
Studies of rift, seep, and mid-ocean ridge 
biotas have provided a base of new data on the 
inhabitants of deep sections of the ocean that is 
not commonly available. In some cases these 
efforts have taxonomic or nomenclatural 
ramifications in our own shallower-water 
fauna. Calder (1996, & 1997) and Calder & 
Vervoort (1998) all deal with the deep-water 
hydroid fauna of the Atlantic. Calder (1998) 
provides an interesting examination of depth 
zonation in the hydroid fauna from shallow 
coastal shelf waters into the deep sea off 
Bermuda, which helps show how the shallow 
and deep fauna differ, and where they are 
similar. For the most part there is no direct 
relationship with the hydroid fauna of the 
Bight, but the discussion of Ectopleura vs. 
Tubularia in Calder & Vervoort is apropos to 
our own fauna. 
The natural history of one hydroid is addressed 
by Cerrano et al (1998), who examine the 
hermit crab associated Podocoryna exigua 
from the Mediterranean. The authors’ careful 
observations in the laboratory demonstrate that 
presence of the hermit crab is necessary for the 
colonial commensal development of the 
hydroid, and that once the crab leaves the shell, 
a healthy active hydroid colony rapidly 
regresses. If a crab is reintroduced to the shell 
the colony remnant resumes it’s earlier active 
growth. Despite this, the relationship is not 
obligate, as solitary polyps are found in 
sediments. Observations of the hydroid feeding 
showed that different parts of a colony fed on 
different prey, with buried polyps selectively 
ingesting sediment particles, while exposed 
polyps feed more normally on plankters at the 
sediment/water interface. 
During regression of abandoned colonies the 
authors confirmed earlier observations that 
hydractinid spines are formed by polyp 
regression, and represent sites at which polyps 
were earlier situated. In Podocoryna the spines 
lasted only a few weeks before being abraded 
away. 
The crabs apparently benefit from the 
association as well (although the hydroids were 
observed to feed on newly released crab larvae) 
by stealing zooplankters caught by zooids near 
the aperture of the shell. 
Morphological variability in soft corals and the 
ability to detect the limits of variability in a 
given species were discussed by Benayahu 
(1998) and McFadden (1999). As many 
cnidarians adopt different ecophenotypes 
depending on the hydrodynamics of their 
attachment site, recognition of species 
boundaries is a continuing subject of debate in 
the group. Benayahu describes lobe variation in 
one soft coral, stressing the need to pay 
attention to the morphology of the entire 
colony when making species distinctions. 
McFadden also draws in genetic testing 
(examination of allozyme distributions) to 
“ground truth” morphology based observations. 
Both their discussions are useful in considering 
variability of local octocorals. 
Predator/prey interactions can also alter soft 
coral appearance and behavior. In addition to 
stinging cells (cnidae), production of toxic 
compounds to deter predators is often used by 
various cnidarians, not always successfully. 
Slattery et al (1998) discuss the uptake and 
sequestration of a soft-coral produced diterpene 
by an aeolid nudibranch. This mollusk has been 
able to co-opt the cnidarian’s defense to it’s 
own use, offering the soft bodied nudibranch 
protection from fish predation. 
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