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P. S. MEADOWS AND J. I. CaMPBELL
chaete, a choice of salinities in a vertical column and found larvae collecting at a salinity of 12%, which would have killed them in a few hours.
It would appear, then, that some animals choose habitats which will
eventually kill them. If this conclusion is not based on experimental
artifact, these seem to be instances of habitats selecting animals rather
than animals selecting their habitat. Turning to the terrestrial environment, there are clear cut cases amongst insect parasites of the parasite’s
habitat-its hostselecting the parasite, in other words killing it.
A number of ovipositing insects cannot distinguish between insect hosts
in which their progeny will develop successfully and hosts in which
their progeny will die (Balfour-Browne, 1922 ; Cendaiia, 1937 ; Ishii,
1952) and this is apparently most marked in the parasitic Diptera
(Salt, 1938). It would be extremely interesting to know if any aquatic
parasites show similar lack of discrimination to their hosts. The only
vaguely related work we know of is by Carton (1967), who transplanted
the parasitic marine copepod Sabelliphilus sarsi from its normal polychaete host Spirographis spallanzani to two closely related species.
I n both transplants the copepod was eventually rejected after a series
of tissue reactions followed by scab formation. However the work is
not strictly comparable because in nature the copepod is not found on
the two species to which it was transplanted.
Animals are continuously assessing the suitability of their environment and moving from place to place so that they can take best
advantage of the range of conditions available to them. Little is known
of how their physiology alters as they do so or as they remain for a
while in an unsuitable environment. Oxygen consumption has been
used as an index of the metabolic activity of mayfly nymphs in sediments of different particle size (Eriksen, 1963; Wautier and PattBe,
1955) and of Corophium in different salinities (McLusky, 1969). The
mayfly nymphs were less active and their oxygen consumption was
lowest in the preferred sediments, whereas the oxygen consumption of
Corophium, although very variable, did not vary consistently between
salinities even though some of the latter were avoided in choice
experiments (McLusky, 1970). Further work would be worthwhile
particularly since some early experiments by Allee (1927) indicate a
similar lowering of oxygen consumption in starfish after they have
aggregated into clumps.
Sakai (1962) has studied the relation between growth, maturity and
food preferences in the marine gastropod Haliotis discus hannai Ino.
Haliotis will eat a number of species of brown, green, and red seaweeds,
but shows distinct preferences if offered a choice (Table VI). Its rate of
feeding, efficiency of food conversion, increase in weight and develop-
P. S. MEADOWS AND J. I. CaMPBELL
chaete, a choice of salinities in a vertical column and found larvae collecting at a salinity of 12%, which would have killed them in a few hours.
It would appear, then, that some animals choose habitats which will
eventually kill them. If this conclusion is not based on experimental
artifact, these seem to be instances of habitats selecting animals rather
than animals selecting their habitat. Turning to the terrestrial environment, there are clear cut cases amongst insect parasites of the parasite’s
habitat-its hostselecting the parasite, in other words killing it.
A number of ovipositing insects cannot distinguish between insect hosts
in which their progeny will develop successfully and hosts in which
their progeny will die (Balfour-Browne, 1922 ; Cendaiia, 1937 ; Ishii,
1952) and this is apparently most marked in the parasitic Diptera
(Salt, 1938). It would be extremely interesting to know if any aquatic
parasites show similar lack of discrimination to their hosts. The only
vaguely related work we know of is by Carton (1967), who transplanted
the parasitic marine copepod Sabelliphilus sarsi from its normal polychaete host Spirographis spallanzani to two closely related species.
I n both transplants the copepod was eventually rejected after a series
of tissue reactions followed by scab formation. However the work is
not strictly comparable because in nature the copepod is not found on
the two species to which it was transplanted.
Animals are continuously assessing the suitability of their environment and moving from place to place so that they can take best
advantage of the range of conditions available to them. Little is known
of how their physiology alters as they do so or as they remain for a
while in an unsuitable environment. Oxygen consumption has been
used as an index of the metabolic activity of mayfly nymphs in sediments of different particle size (Eriksen, 1963; Wautier and PattBe,
1955) and of Corophium in different salinities (McLusky, 1969). The
mayfly nymphs were less active and their oxygen consumption was
lowest in the preferred sediments, whereas the oxygen consumption of
Corophium, although very variable, did not vary consistently between
salinities even though some of the latter were avoided in choice
experiments (McLusky, 1970). Further work would be worthwhile
particularly since some early experiments by Allee (1927) indicate a
similar lowering of oxygen consumption in starfish after they have
aggregated into clumps.
Sakai (1962) has studied the relation between growth, maturity and
food preferences in the marine gastropod Haliotis discus hannai Ino.
Haliotis will eat a number of species of brown, green, and red seaweeds,
but shows distinct preferences if offered a choice (Table VI). Its rate of
feeding, efficiency of food conversion, increase in weight and develop-