338
P. 5. MEADOWS AND J. I. OAMPBELL
Naylor (1959). Reports of conflict between laboratory experiments
and field distribution might represent other examples. Amongst 10
freshwater species of insect larvae and nymphs and one gastropod
investigated by Cummins and Lauff (1969), the substrate preferences
of 6 appear to disagree with their field distribution. Presumably other
variables take precedence in the field. Bovbjerg (1970) recorded a
discrepancy between the results of laboratory experiments and field
distribution in two species of crayfish which was clearly the result
of interspecific competition (see Section VIII), and finally, the freshwater bivalve Sphaerium transversum (Say) , although preferring mud
in choice experiments is equally common in sand, sandy mud or mud
sediments (Gale, 1971). Gale could not account for his findings but
suggested that other factors in the environment overrode the species
substrate preferences.
It is
obviously advantageous for an animal to be able to choose B or C or D
until A again is encountered or reappears in the environment. Several
species behave in this way. I n the freshwater environment, the aquatic
larvae of the moth Bellura will eat and thrive on white waterlily leaves
if their preferred food of yellow waterlily leaves is not available (Welch,
1914), and caddis fly larvae will use for case building less preferred
materials if deprived of more suitable ones (Gorter, 1929 ; Fankhauser
and Reik, 1935; Hanna, 1961). The intertidal crustaceans Uca pugilator (Bosc) and Corophium volutator and the sublittoral species Callianassa islagrande Schmitt burrow in unfavourable sediments when
presented with these or with even less suitable sediments (Teal, 1958;
Meadows, 1964c; Phillips, 1971), the hermit crab Pagurus hirsutiusculu8
will accept less suitable gastropod shells if its preferred shell is not
available (Orians and King, 1964), and the settling larvae of the marine
polyzoan Bugula neritina L. will settle on slime-free surfaces although
they normally avoid these if offered a choice (Miller, Rapean and
Whedon, 1948). Radwin and Wells (1968, p. 81), after studying the
prey preferences of seven species of muricid gastropods for the three
species of bivalve, made an interesting distinction between three of the
muricid species which were highly selective and fed on only one of
the bivalve species, and two of the muricid species which although
preferring one bivalve species would on occasion eat the other two.
Concerning the latter species of muricids, Murex fulvescens Sowerby
and Urosalpinx tampaensis, they state that ‘‘ when the supply of preferred prey was exhausted, these snails attacked the remaining bivalve
prey with little selectivity, and when the bivalves were consumed, they
attacked and consumed one another ”. Without further study it is
difficult to weigh the disadvantages of not being willing to eat other
What happens if the preferred habitat A is not available?
P. 5. MEADOWS AND J. I. OAMPBELL
Naylor (1959). Reports of conflict between laboratory experiments
and field distribution might represent other examples. Amongst 10
freshwater species of insect larvae and nymphs and one gastropod
investigated by Cummins and Lauff (1969), the substrate preferences
of 6 appear to disagree with their field distribution. Presumably other
variables take precedence in the field. Bovbjerg (1970) recorded a
discrepancy between the results of laboratory experiments and field
distribution in two species of crayfish which was clearly the result
of interspecific competition (see Section VIII), and finally, the freshwater bivalve Sphaerium transversum (Say) , although preferring mud
in choice experiments is equally common in sand, sandy mud or mud
sediments (Gale, 1971). Gale could not account for his findings but
suggested that other factors in the environment overrode the species
substrate preferences.
It is
obviously advantageous for an animal to be able to choose B or C or D
until A again is encountered or reappears in the environment. Several
species behave in this way. I n the freshwater environment, the aquatic
larvae of the moth Bellura will eat and thrive on white waterlily leaves
if their preferred food of yellow waterlily leaves is not available (Welch,
1914), and caddis fly larvae will use for case building less preferred
materials if deprived of more suitable ones (Gorter, 1929 ; Fankhauser
and Reik, 1935; Hanna, 1961). The intertidal crustaceans Uca pugilator (Bosc) and Corophium volutator and the sublittoral species Callianassa islagrande Schmitt burrow in unfavourable sediments when
presented with these or with even less suitable sediments (Teal, 1958;
Meadows, 1964c; Phillips, 1971), the hermit crab Pagurus hirsutiusculu8
will accept less suitable gastropod shells if its preferred shell is not
available (Orians and King, 1964), and the settling larvae of the marine
polyzoan Bugula neritina L. will settle on slime-free surfaces although
they normally avoid these if offered a choice (Miller, Rapean and
Whedon, 1948). Radwin and Wells (1968, p. 81), after studying the
prey preferences of seven species of muricid gastropods for the three
species of bivalve, made an interesting distinction between three of the
muricid species which were highly selective and fed on only one of
the bivalve species, and two of the muricid species which although
preferring one bivalve species would on occasion eat the other two.
Concerning the latter species of muricids, Murex fulvescens Sowerby
and Urosalpinx tampaensis, they state that ‘‘ when the supply of preferred prey was exhausted, these snails attacked the remaining bivalve
prey with little selectivity, and when the bivalves were consumed, they
attacked and consumed one another ”. Without further study it is
difficult to weigh the disadvantages of not being willing to eat other
What happens if the preferred habitat A is not available?