4 
PACIFIC SCIENCE, Vol. XVIII, January 1964 
and ferry dock facilities at one end and a some- 
what rocky prominence at the other end. Thus 
relatively calm water free from strong currents 
exists. The substrate grades from rocky rubble 
to almost pure mud. In one area a small stream 
drains into the Titlow Beach habitat and has 
formed an underwater delta consisting of mud 
and coarse sand. Along the upper margin of 
the beach large boulders have been placed as a 
retaining wall, thus affording a site where spray 
zone animals and plants may live. This beach is 
typical of most Puget Sound intertidal areas. 
The second site studied was at the Point De- 
fiance boathouse. Situated on the north side of 
Point Defiance, it opens to the Dalco Passage. 
The immediate area associated with the boat- 
house is similar to that of Titlow Beach, for 
rock rubble covers much of the shell-fragment 
and coarse sand substrate. Adjacent to the boat- 
house, however, a long expanse of beach extends 
toward the north and west and affords a heavy 
growth of Zoster a marina. At this site those 
species that dwell typically on pilings or under 
rock rubble or within the Zostera beds were 
studied. 
The third site frequently visited was under 
the Narrows Bridge in that confined stretch 
of water known as the Tacoma Narrows. This 
is the only drainage site for the extremely 
large southern arm of Puget Sound and hence 
the currents ''boil” through the Narrows at a 
high velocity during the changing of the tide. 
On the east side of the Narrows very large 
boulders have been placed by the railroad com- 
pany to retain the banks. A limited number of 
very narrow beaches extend out from these 
boulders. From the low low-water mark the 
substrate frequently drops off abruptly to depths 
that appear to be 15 ft or more. This habitat is 
so heavily washed by swift currents that sedi- 
ments not protected by rocks are swept away. 
Those animal and plant species that fully require 
a protected outer rocky coast with fairly strong 
oceanic waves often exist here because the high 
velocity of the current serves as a substitute for 
waves. This site was visited whenever the tides 
were sufficiently low to insure good collecting. 
Three other sites were visited on occasion. 
Gig Harbor, just north of Tacoma, is a well- 
protected area with a muddy bottom and a large 
number of piers and floating boat docks. This 
site was examined occasionally for the large 
number of spider crabs that could be found 
there. Quartermaster Harbor across from the 
Point Defiance Aquarium offered a large num- 
ber of piers for collecting. Another site visited 
three or four times annually was near the light- 
house in the Port Orchard channel just north 
of Port Orchard, about 1 mile southwest of Point 
Glover and across the channel from White Point. 
The prominence at the lighthouse is a natural 
headland composed of very large boulders that 
project out into the waterway. Like the Nar- 
rows, this site has extremely heavy currents; 
unlike the Narrows, however, the rocks project 
straight out into the current rather than simply 
forming a margin along the current. This site 
was well provided with invertebrates, some of 
which are found almost exclusively in the outer 
reaches of Puget Sound or in the protected open 
oceanic coastline. Likewise the flora was more 
reminiscent of that of the protected rocky coast- 
line. Here many of the species of crabs that had 
been encountered in southern Puget Sound were 
also present, but in addition such genera as 
Pachycheles were found. 
METHODS AND MATERIALS 
field COLLECTING: The tide in the eastern 
Pacific is a mixed tide, thus giving unequal 
lows or highs during any given day. About 
every 14 days a period of low tides occurred 
but only once out of each month would the tide 
be sufficiently low to enable the collection of 
specimens which live at the extreme lower limits 
of the intertidal zone. Several collecting trips 
were made during each series of low tides. Dur- 
ing the transitional periods of tidal change (Jan- 
uary-March and September-October) bimonthly 
collecting was continued and an endeavor was 
made to obtain all of those species under study, 
even though the depth of the tides was not 
adequate. However, it was necessary to use 
laboratory animals in part to fill in where field 
records were not obtainable. In many instances 
it was felt that the laboratory data were not 
obtained under natural conditions and thus these 
have been disregarded in the final analysis. Col- 
lecting was always carried out by hand or by 
hand-operated nets and dredges. 
