Polychoerus carmelensis and Temperature Changes — Schwab 
87 
TABLE 1 
Reactions of P. carmelensis To Changes in Ambient Water Temperature* 
TEMPERATURE 
(°C) 
LOCOMOTION RATE 
Average 
(mm/min) 
Range 
STANDARD 
DEVIATION 
STANDARD ERROR 
OF THE MEAN 
3 ❖ * 
5 
17.4 
5.0- 32.5 
6.83 
1.51 
8 
44.9 
25.0- 62.5 
9-81 
2.19 
11 
64.8 
40.0- 90.0 
14.21 
3.18 
14 
83.0 
62.5-115.0 
14.70 
3.25 
17 
90.4 
57.5-122.5 
17.06 
3.82 
21 
78.5 
45.0- 95.0 
13.89 
3.10 
25 
66.2 
45.0- 87.5 
11.40 
2.53 
29 
50.2 
35.0- 62.5 
7.41 
1.65 
33 
o er sfe 
32.8 
17.5- 65.0 
11.49 
2.57 
35** 
38** 
* A total of 20 individuals was tested at each of the temperatures. 
** See text. 
1-3 minutes. Thereafter disintegration of the 
tissues took place. Some of the flatworms tested 
at this temperature immediately formed the U- 
shaped posture. After about a minute most indi- 
viduals reoriented to the curled posture and 
moved about for a minute or two. After this 
short period of movement they again formed 
the U-shaped posture and all movement ceased. 
Animals removed after about 3 minutes’ expo- 
sure to 33 °C water temperature did not recover 
when placed in 14°C sea water. An exposure of 
5-10 minutes at this temperature results in an 
apparently complete disorganization of the body 
structure. 
Exposure to sea water at a temperature of 
35 °C resulted in a very brief but rapid locomo- 
tion by several of the 20 individuals tested. 
Generally this occurred while the animal was 
in the curled posture. However, most individ- 
uals remained in the U-shaped posture assumed 
immediately upon contact with the 35 °C water 
and had no measurable amount of locomotion. 
All animals showed signs of tissue disintegra- 
tion within 60 seconds after exposure. 
Polychoerus exposed to sea water at 38 °C ap- 
peared to die immediately. Several individuals 
were dipped into water at this temperature and 
then quickly returned to 14° C sea water but 
there were no recoveries. 
DISCUSSION 
The locomotion rate of P. carmelensis was 
clearly related to the water temperature under 
the conditions of these experiments. The nearly 
uniform increase of locomotion rate at 6.1 
mm/min/°C rise in temperature between 5° 
and 17°C suggests that changes in tide pool 
temperatures may have a pronounced effect on 
the activity and behavior of this species. The 
mechanism by which temperature induces in- 
creased locomotion activity is not known. How- 
ever, it is likely that this accelerated locomotion 
is fundamentally similar to the increases of 
chemical and physical reactions normally asso- 
ciated with an increase in temperature. Many 
biological processes, including rate of develop- 
ment, behavioral reactions, speed of locomotion, 
and metabolism show increases associated with 
higher temperatures (Prosser and Brown, 
1961 ). 
It is significant that the highest rate of loco- 
motion occurred at a temperature (17°C) near 
that measured in these tide pools during late 
spring. This suggests that the maximum loco- 
motion rate of Polychoerus may be a function 
of the most suitable ambient environmental 
temperature with respect to possible acclimatiza- 
tion of the animal. 
The decrease in locomotion rate measured at 
ambient water temperatures above 17°C (4.4 
mm/min/°C rise in temperature between 17° 
and 33 °C) is considerably less than that mea- 
sured for locomotion increases (6.1 mm/min/°C 
rise in temperature between 5° and 17°C). 
This suggests a temperature-related differential 
