C
Haberman p. 2
Although centipedes are primarily terrestrial organisms,
some members of the Order Geophilomorpha have been observed in
the littoral zone. One species along English shores, Hydro-
schendila submarina, tolerates 14 hours of submersion in sea-
water (Binyon and Lewis, 1963). The European species Scolde
planes maritimus has been observed to feed upon barnacles and
littorine snails (Blower, 1957). Recently, specimens of Geophilus
becki, also in the Order Geophilomorpha, were found between the
alga Endocladia muricata and iceplant borderline, markers of sea
and land vegetation respectively, along the Monterey Bay
shoreline. Positive identification was made by comparing col¬
lected specimens with animals previously collected along the
Monterey Peninsula by Mr. Roy Johnson, and identified by Dr.
R.L. Crabill of the Smithsonian Institution. Unidentified species
in the Order Lithobiomorpha were also found. The purpose of
this study was to determine the distribution of centipedes near
the shore, and to define the habitatt of G. becki.
MATERIALS AND METHODS
Sites were chosen along the shore between Lover's Point
and Pt. Pinos, Pacific Grove, California (fig. 1). During pre-
liminary surveys, all centipedes found were beneath rocks,
in gravel substrate, so the following criteria were used in
choosing study sites and transects. (1) All sites had many rocks.
(2) All sites had some gravel in the substrate. (3) Transects
were not established in areas containing only large, immovable
rocks.
C
Haberman p. 3
Site 1 was most exposed, receiving direct, unblocked wave
action at high tide. Site 2 was least exposed, with most wave
action blocked by an outcropping rock cliff.
At each site, transects were established perpendicular to
shore, extending from the land vegetation, across the area re¬
ceiving splash and spray, to the upper midtide region. Tran¬
sects were 1 meter in width, and divided into 2 meter intervals
along the surface of the slope. The erect alga occurring
highest in the intertidal region (usually Endocladia muricata)
was used to mark the boundary between Zones A and B.
Within each defined zone of a transect, all movable rocks
large enough to be firmly pressed against the substrate and house
a centipede were overturned and counted. (Rocks atop other rocks
were found not to conceal centipedes, and were therefore not
counted.) The area beneath each rock was examined for centi¬
pedes; some centipedes were visible upon overturning the rock,
and others were searched for by digging with a trowel to a depth
of 10-15 cm into the substrate under the rock.
Along some transects, centipedes were found but not col¬
lected. Those centipedes were counted in the field, and not handled
unless found in large groups. Large groups were temporarily
sequestered by scooping them up in a jar, and the animals counted
while taking each individual out and replacing it on the sub-
strate where found. Along the remaining transects, all centipedes
found were collected. Individuals and small groups were oounted
at the collecting site, while large groups were collected and
later counted and measured in the laboratory. Escapees were also
counted.
Haberman p. 4
For each individual or group of centipedes found, con-
ditions of moisture, substrate, type of environment (under rock
or in drift) and other organisms found with centipedes were re¬
corded. In addition, average values for these parameters were ae¬
estimated for each entire zone, based upon conditions under all
rocks overturned.
The composition of the dominant elements of the substrate
beneath each rock (sand, gravel, and soil) were recorded using
the following categories: (1) Bome present, (2) Present in
approximately equal proprtions with another type, (3) Present
as the dominating type, and (4) Exclusively present.
Moisture under rocks was assessed on the following scale:
(1) Substrate dry, (2) Substrate dry at surface, moist beneath,
(3) Substrate moist from surface downward, (4) Substrate with
water droplets visible and/or wet to touch, (5) Rock and substrate
submerged
Amount of drift algae in each zone was estimated on a scale
from 1 to 5, using the following categories: (1) None present,
(2) Present, but scattered and thin, (3) Isolated patehbssof
drift covering some rocks, (4) Large patches of drift covering
up to 50% of zone, (5) 50-100% of zone is covered with drift
approximately 1 footdeep, erdeeper.
All surveys were conducted in the period May 12- May 26,
1982, at tidal levels in the field ranging from a lower low
water (LLW) level of -1.6 feet to the rising tide of a lower high
water (LHW) of 4.3 feet. No zones were surveyed while submerged.
Haberman p. 5
RESULTS
Results of this study are illustrated in Fig. 2-10.
The data for Site 2 (Fig 2) show that Zone C has a density
of G. becki significantly higher than any other zone. This
zone is characterized by a gravel substrate which is moist to
wet at the surface; it is just above the region of maximum
drift algae, and contains numerous amphipods.
This zone is generally covered once a day during higher high
water (HHW). No significant differences or trends were observed
between two side by side transects when one was surveyed at LLW
and the other surveyed close to LHW (Fig. 3).
Several organisms were found in the drift.
Sites 1, 3,and 4 had much lower densities of G. becki
(Fig. 4, 5, and 6). The zones of highest centipede density for
Sites 3 and 4 are characterized by approximately the same conditions
as those with the most centipedes in Site 2, while the zone for
Site 1 occurs at a higher tidal level, isodryer and farther
above the drift, and contains no amphipods.
Centipedes of the Order Lithobiomorpha were scarce and
found only near land vegetation, except at Site 4.
Most centipedes found were on substrata which were moist but
not wet at the surface (Fig. 7). However, zones B and 66 which
containea majoréty of the goneipedes, are submerged at HHW.
The majority of centipedes were found in groups. Zones
of highest density contained the largest groups (Fig. 1).
Groups ranged in size from 2 to 16 members, and smaller indi-
viduals had a higher percentage of membership in large groups
(Fig. 8). Size distribution of all measured centipedes is
shown in Fig. 9. Mean size did not vary between zones (Fig. 10).
Haberman p. 6
DISCUSSION
The location of the main body of the G. becki population
indicates that the species is part of the littoral or drift
community. Since some G. becki were found wandering in loose
drift, the centipedes may be feeding there. The number of drift
wanderers found may be much lower than the number actually there,
due to the relative difficulty of finding the animals in the
drift as compared to finding them under rocks.
The high density of G. becki at Site 2 suggests that both a
large number of rocks and presence of alot of drift provide
optimum conditions for this species. Only Site 1 had close to
the density of drift at Site 2, and it contained many fewer rocks.
The centipede population is concentrated in a zone which
is submerged once per day. Furthermore, individuals in Zone B
were found while the tide was rising to LHW, and this zone is
submerged at LHW. At the Pt. Pinos site, two specimens were
found together in Zone B ten minutes before the zone was sub-
merged. All this evidence suggests that G. becki do not avoid
submergence in seawater, and may be regularly submerged.
Most centipedes at Site 1, which was most exposed to wave
action, occurred at a higher tidal level than was the case for
the rest of the sites, suggesting some avoidance to strong wave
action or submergence. The Site 1 distribution may also be in¬
fluenced by the low numbers of rocks in all zones.
The high percentage of centipedes found in grospessuggests that
G. becki is a social animal, and the high percentage of small cen¬
tipedes in large groups indicates a possible "young care'
function for the ggroups. However, the occurance of larger and
C
C
Haberman p. 7
more abundant groups in the most populated zones may be due to
crowding. The distribution of centipedes within any zone (at
least in daylight at low water) is always patchy since the animals
hide under stones, and group size may in part reflect the ratio
of population density to the number of suitable rocks present.
The size distribution curve shows a bimodal trend; however,
this is obviously not a statistically significant result.
SUMMARY
Centipede populations in the splash zone of Monterey Bay
were surveyed, and a high density of the Geophilomorph
Geophilus becki was found beneath the rocks in a zone just above
the attached alga Endocladia muricata and below a tidal level of
+5.6 feet. A high percentage of these were found in groups. Few
Lithobiomorpha were found in the splash zone.
C
ACKNOWLEDGEMENTS
I would like to thank Dr. Donald P. Abbott for his extensive

involvement in this project at all stages, his enthusiasum, and
his very useful criticism. I would also like to thank Mr. Roy
Johnson for use of identified G. becki specimans, without which
the identity of the critter would have remained a mystery, and
I would like to thank Chris Patton for the up close and personal
view of the animal using electron microscopy. And of course, I
must thank Freya Sommer for putting up with me for the entire
quarter.
C
). 8
Haberman p.9
REFERENCES
Binyon, J., Lewis, J.G.E., 1963. Physiological adaptations of two
species of centipede to life on the shore. J. Mar. Biol. Assn.
U.K. 43: 49-55.
Blower, J.G., 1957. Feeding habit of a marine centipede.
Nature 180: 560.
C
Haberman p. 10
Captions
Map of Pacific Grove coastline, depicting study site
Figure 1.
locations.
Combined results for 7 transect surveys at site 2,
Figure 2.
relating physical and biological parameters to
centipede distribution.
Data from 2 pairs of transects in site 2. Transects
Figure 3.
1 and 3 (Tl and T3) were surveyed close to LLW, while
transects 2 and 4 (T2 and T4) were surveyed during the
rising tide and close to a LHW of approximately 14.5 feet.
Figure 4. Combined results for 2 transect surveys at site 1.
Figure 5. Results for a single transect survey at site 3.
Figure 6. Results for a single transect survey at site 4.
Figure 7. Moisture conditions for individual centipedes. Data
from all sites and zones åre combined.
Figure 8a. Group size frequencies. Data from all sites and zones
are combined.
C
Haberman p. 11
Captions (cont.
Figure 8b.
Relationship of centipede size to group membership,
All measured centipedes were tabulated, and data from
all sites and zones were combined.
Figure 9. Size distribution of all measured specimens of G. Becki.
Figure 10.
Size distribution as related to zonation. Data
compiled using measured specimens from site 2 transects
only.
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Haberman p.13


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Hobermanp.16


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Hoberman 9.16




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Amphipods
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Bristletails
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ZONE A ZONE B
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210
Ants
Isopods
Bristletalis
ZONE L
Haberman p.11

K
Ants
Isopods
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ZONE
(

moisture
rating
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no. of
cemipedes
213
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Haberman p. 18
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Fig 85
Hoberman P.19
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8
10
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16

—

NO. OF INDIVIDUALS IN GROUP
LARGE INDIVIDUALS=6.0-9.5 cm
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Haberman p.2