158 
PACIFIC SCIENCE, VoL XII, April, 1958 
COLLECTIONS AND HABITATS 
Unfortunately the collections from Onotoa 
are not very extensive. An infected leg pre- 
vented me from collecting for about half of 
the 10 weeks we spent on the island, and in 
the short time remaining I had to devote full 
time to making the ecological survey, collect- 
ing snapping shrimps only as they appeared 
in the transects. Most of this small collection 
was lost in transit from Onotoa via Kwajelein 
to Hawaii and, eventually, only a small propor- 
tion of the shrimp collected at Onotoa ar- 
rived in Honolulu. Most of the specimens 
available for study were those collected by 
Dr. Cloud incidental to his studies on marine 
geology. However, small as the collection is, 
it is important for there have been no previous 
records from the Gilbert Islands. 
On the windward reef a transect 20 feet 
wide was taken normal to the beach line and 
reaching to the coralline ridge, 750 feet to 
seaward. Because of the great diversity of 
habitats and the limitations of time no ex- 
tensive transects were taken on the lagoon 
side, but the different shallow water habitats 
were sampled individually (see Banner and 
Randall, 1952). 
The ecological notes on the stations from 
which shrimp were examined (it should be 
noted that alpheids were collected at almost 
all stations) are as follows: 
A-l. Starting with division between beach 
rock and higher sand beach, at about 2.4-foot 
tide zone, reaching seaward 50 feet; substrate 
of consolidated reef limestone; many tide 
pools, the largest up to 20 feet long, 5 feet 
wide, and 6 inches deep; both exposed areas 
and bottoms of tide pools with scattered 
loose rocks up to a foot square and 6 inches 
thick. 
A-2. 50-100 feet from beach line, about 
2.2-foot tide zone; similar in nature to A-l, 
but with fewer and smaller tide pools. 
A-3. 100-150 feet from beach line, about 
2. 0-foot tide zone; substrate similar to A-l, 
A-2. 
(approximalt) 
Fig. 1. Onotoa, Gilbert Islands, showing localities 
of collections. Place indicated by X is approximately 
1°47' S., 175°29' E. 
A-6. 250-300 feet from beach line, about 
1.4-foot tide zone; about 30 per cent of area 
covered by very shallow tide pools. Substrate 
changing to a coralline algal sheet overgrow- 
ing dead coral heads in situ with numerous 
small holes passing through sheet into cavi- 
ties remaining between the coral heads. 
A-7. 300-350 feet from beach line, about 
1.2-foot tide zone; about 80 per cent of the 
area covered by 1-inch-deep tide pools that 
only drain on extreme low waters; substrate 
as in A-6, but carpeted by thick tufts of green 
