274
P. 9. MEADOWS AND J. I. CAMPBELL
Lagerspetz and Lehtonen, 1961 ; Perttunen, 1961 ; Williamson, 1951a)
and the intertidal sand beetle Thinopinus pictus Leconte (Craig, 1970)
preferred more humid habitats in choice experiments.
It is a common observation that clean and also fairly coarse sands
on intertidal sand banks can drain and become appreciably dry as the
tide recedes. There are passing references to Nereis, Arenicola and
amphipods finding dificulty in burrowing under these conditions
(Maxwell, 1897, p. 277; Chapman and Newell, 1947, p. 448; Chapman,
1949, p. 136; Croker, 1967, p. 187), but no detailed studies.
Most intertidal animals live under stones, in crevices or within sediments. They may either live there all the time or retire there as the tide
falls. Onemight expect, therefore, that if their distribution is determined
by their light responses, the former would be photonegative both
n
r
‘ 6 Light
FIQ. 1. The light reactions of Littorina neritoides i n sea water. Animals move away
from light except when upside down. Thin arrows indicate direction of movement.
(From Fraenkel, 1927.)
in and out of water, and the latter photonegative when exposed but
indifferent or even photopositive when immersed. Few workers have
considered these points. Chitons, littorinids and isopods are photonegative in air (Mitsukuri 1901; Evans 1951; Perttunen, 1961; Croker,
1967) but their responses were not recorded under water, while
gammarids, isopods and polychaetes are photonegative under water but
their responses were not tested when out of water (Herter, 1926;
Wolsky and Huxley, 1932; Clark, 1956; Jansson and Kallander, 1968).
There are a number of fairly detailed studies on the light reactions
of intertidal animals. Littorim neritoides (L.) is photonegative under
water, except when upside down when it moves towards light (Fig. 1)
while if exposed it is consistently photonegative (Fraenkel, 1927). These
observations help to explain why L. neritoides is found in crevices
towards high water. It moves into and then out of crevices under
P. 9. MEADOWS AND J. I. CAMPBELL
Lagerspetz and Lehtonen, 1961 ; Perttunen, 1961 ; Williamson, 1951a)
and the intertidal sand beetle Thinopinus pictus Leconte (Craig, 1970)
preferred more humid habitats in choice experiments.
It is a common observation that clean and also fairly coarse sands
on intertidal sand banks can drain and become appreciably dry as the
tide recedes. There are passing references to Nereis, Arenicola and
amphipods finding dificulty in burrowing under these conditions
(Maxwell, 1897, p. 277; Chapman and Newell, 1947, p. 448; Chapman,
1949, p. 136; Croker, 1967, p. 187), but no detailed studies.
Most intertidal animals live under stones, in crevices or within sediments. They may either live there all the time or retire there as the tide
falls. Onemight expect, therefore, that if their distribution is determined
by their light responses, the former would be photonegative both
n
r
‘ 6 Light
FIQ. 1. The light reactions of Littorina neritoides i n sea water. Animals move away
from light except when upside down. Thin arrows indicate direction of movement.
(From Fraenkel, 1927.)
in and out of water, and the latter photonegative when exposed but
indifferent or even photopositive when immersed. Few workers have
considered these points. Chitons, littorinids and isopods are photonegative in air (Mitsukuri 1901; Evans 1951; Perttunen, 1961; Croker,
1967) but their responses were not recorded under water, while
gammarids, isopods and polychaetes are photonegative under water but
their responses were not tested when out of water (Herter, 1926;
Wolsky and Huxley, 1932; Clark, 1956; Jansson and Kallander, 1968).
There are a number of fairly detailed studies on the light reactions
of intertidal animals. Littorim neritoides (L.) is photonegative under
water, except when upside down when it moves towards light (Fig. 1)
while if exposed it is consistently photonegative (Fraenkel, 1927). These
observations help to explain why L. neritoides is found in crevices
towards high water. It moves into and then out of crevices under