ay) PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 125 
The somewhat crude sampling techniques employed also contrib- 
uted to the paucity of free-living crustaceans and other such creatures 
in the buoy collections. A major difficulty was that there was no way 
of preventing unattached forms from deserting the buoy installation 
while it was being hoisted aboard. Also, it was not possible to screen 
the samples by using wash bucket and plankton net procedures for 
extracting small free-living crustaceans from the scrapings. Conse- 
quently, many specimens could be lost or destroyed easily, especially 
if they were small or not abundant. 
Besides sampling problems, other inherent difficulties reduced the 
yield. In the first place, buoy installations obviously comprise an 
extremely small and rather special vertical extension of the benthic 
habitat. Buoys are not sited in all habitat types in an area, nor do 
they necessarily acquire the full complement of species present in 
their vicinity. Space on buoys is limited, especially on the chain, and 
access may be difficult, especially for predominantly benthic species. 
Also, in many instances, chafing or scouring of the lower part of the 
chain may remove or prevent attachment of fouling and associated 
organisms. The fact that only a single isopod or tanaidacean species 
was found on 78 of the 100 buoys from which these crustaceans were 
taken indicates that buoys present rather limited, unnatural habitats 
not particularly attractive to these forms. 
A possible explanation for the marked differences in incidence of 
various crustacean groups is the apparent correlation of frequency of 
occurrence with degree of motility and means of dispersal. Obviously, 
pelagic forms would stand a better chance of finding and boarding a 
buoy installation than would benthic types. The high incidence of 
barnacles and other sessile organisms on buoys can be explained 
readily by the fact that the sessile adults liberate swarms of pelagic 
larvae that find buoys to be a convenient substrate for attachment. 
Peracarid crustaceans, however, including amphipods, isopods, and 
tanaidaceans, generally lack pelagic larval stages, as the females 
carry the young in a subthoracic brood pouch until they are rela- 
tively well advanced. Liberated young usually resemble adults in 
habit and appearance, except for size and minor morphological dif- 
ferences, such as undeveloped seventh legs. 
The high incidence of amphipods (99 percent) and the lesser fre- 
quency of isopods (c. 25 percent) the tanaidaceans (less than 4 percent) 
probably reflects the relative locomotor abilities of these three orders. 
The greater swimming ability of most amphipods could account for 
the fact that they are recorded in greater frequency and with greater 
variety than isopods not only from buoys but from other floating 
or suspended structures such as ships and test panels (Woods Hole 
Oceanographic Institution, 1952). 
