Pseudosquilla Replaced by Gonodactylus — Kinzie 
471 
TABLE 1 
Results of Salinity Tolerance Tests on Gonodactylus falcatus and Pseudosquilla ciliata 
IMMEDIATE IMMERSION EXPERIMENTS 
Gonodactylus falcatus Pseudosquilla ciliata 
% SEAWATER 
NO. OF 
ANIMALS 
LENGTH 
OF TEST 
CONDITION AT 
END OF TEST 
NO. OF 
ANIMALS 
LENGTH 
OF TEST 
CONDITION AT 
END OF TEST 
75 
2 
indef. 
alive 
66 
2 
indef. 
alive 
66 
1 
4 days 
dead 
50 
1 
indef. 
alive 
5 
90 min 
weak 
30 
1 
15 min 
weak 
INCREMENTAL EXPERIMENTS 
NO. OF 
ANIMALS 
Gonodactylus falcatus 
% SEAWATER 
75 
50 
CONDITION AT 
END OF 
PERIOD 
2 hr 
indef. 
alive 
% SEAWATER 
75 
50 
30 
1 
1 hr 
1 hr 
25 min 
weak 
75 
Pseudosquilla ciliata 
% SEAWATER 
CONDITION AT 
ANIMALS 
75 
50 
PERIOD 
1 
2 hr 
3 hr 
dead 
1 
4 hr 
19 hr 
dead 
1 
68 hr 
indef. 
alive 
1 
6 hr 
indef. 
alive 
% SEAWATER 
50 
30 
68 hr 
143 hr 
21/4 hr 
dead 
The numbers of Gonodactylus falcatus and 
Pseudosquilla ciliata larvae are shown in Figure 
5. The numbers of Gondactylus falcatus larvae 
taken during the year’s sampling showed two 
peaks — one from October to January, and one 
from late March to mid-April — although larvae 
of this species were taken throughout the year. 
This was especially true of run C where all but 
three samples contained G. falcatus larvae in 
stage IV. G. falcatus larvae of stages III, V, and 
VI were taken only occasionally. 
During most of the year Pseudosquilla ciliata 
larvae were either absent from the plankton 
samples or were represented by small numbers, 
generally less than Gonodactylus falcatus. How- 
ever, during late spring coincident with the 
peak of G. falcatus , there was a peak in numbers 
of Pseudosquilla ciliata larvae taken in all runs. 
If the year sampled was typical of the situa- 
tion in Kaneohe Bay, Gonodactylus falcatus 
with its two periods of breeding activity would 
have a reproductive advantage over Pseudo- 
squilla ciliata with only one. The fact that Gono- 
dactylus falcatus larvae are generally more 
abundant might only be an indication that larger 
numbers of this species were present in Kaneohe 
Bay at the time the study was made, and might 
not be a measure of relative reproductive ability. 
However, Pseudosquilla ciliata was still very 
common on the sand and mud flats in the bay. 
Behavior 
It was observed in the field that Gonodactylus 
falcatus was apparently more aggressive than 
Pseudosquilla ciliata. Where Gonodactylus fal- 
catus would snap readily with its raptorial claws 
when touched, Pseudosquilla ciliata would only 
occasionally strike. Whenever several Gono- 
dactylus falcatus were put together in an aquar- 
ium with few places to hide, there was con- 
stant fighting and usually only the largest sur- 
vived. This was found to occur even when the 
animals were only a little more than 2 cm long. 
On the other hand, Pseudosquilla ciliata indi- 
