308
P. 9. MEADOWS AND J. I. CllMPBELL
experiments where extracts of both species are serially diluted;
furthermore, although extracts of other arthropods tested are fairly
active (the cuticle of all arthropods contains arthropodin-like proteins),
extracts of representatives from other phyla in general lack activity
(Crisp and Meadows, 1962, Fig. 3, Tables 8 and 15) (Table IV). The
larvae of Ostrea edulis also recognize chemical differences between
their own and other species (Bayne, 1969).
The chemical basis and chemical specificity of gregarious settlement by larvae of marine sedentary organisms is therefore well
established. On the other hand, it is not known how the gregarious
tendency of larvae varies from species to species, nor is there any
indication of how gregarious behaviour might interact with other larval
responses to produce the patterns of distribution occurring in nature.
Variation between species could be measured by comparing the degree
of aggregation of different species of settling larvae under uniform
experimental conditions using nearest neighbour methods (cf. Edgar
and Meadows, 1969; Campbell and Meadows, 1972), and the interaction
of gregarious responses with other aspects of larval behaviour should not
be difficult to investigate.
The large body of information on the gregarious behaviour of larvae
at settlement contrasts markedly with the little that is known of
gregariousness in adult animals. There is no reason why mobile adult
animals such as the adults of many molluscs, echinoderms and
crustaceans should not be gregarious, but they have not as yet attracted
much attention.
Similarly, little is known of any gregarious
tendencies amongst the young of such groups as the free-living
nematodes, viviparous echinoderms, or amphipod and isopod Crustacea,
in which there is no larval stage and therefore no metamorphosis, and
in which the young bear a strong resemblance to the adult (Sheader
and Chia, 1970). Let us now, therefore, consider the evidence for
gregarious behaviour by adult animals.
The only records of gregarious behaviour in adult planktonic animals
are those of Bainbridge (1952) on Calanus and of Clutter (1969) on
mysids. Both authors describe swarms in the sea ranging in size
from about 12 individuals (Calanus) to more than 1000 individuals
(mysids). Clutter concludes from his experiments that mysid swarms
are maintained by visual clues during the day and perhaps by body
contact and swimming currents in darkness.
Little is known of gregarious behaviour by adult sublittoral animals
living in or on sediments, although the observations of divers imply it
may be fairly general. The spider crab Maia s q u i d 0 (Herbst) forms
heaps or pods of about 1 m diameter and 0.6 m high in which there may
P. 9. MEADOWS AND J. I. CllMPBELL
experiments where extracts of both species are serially diluted;
furthermore, although extracts of other arthropods tested are fairly
active (the cuticle of all arthropods contains arthropodin-like proteins),
extracts of representatives from other phyla in general lack activity
(Crisp and Meadows, 1962, Fig. 3, Tables 8 and 15) (Table IV). The
larvae of Ostrea edulis also recognize chemical differences between
their own and other species (Bayne, 1969).
The chemical basis and chemical specificity of gregarious settlement by larvae of marine sedentary organisms is therefore well
established. On the other hand, it is not known how the gregarious
tendency of larvae varies from species to species, nor is there any
indication of how gregarious behaviour might interact with other larval
responses to produce the patterns of distribution occurring in nature.
Variation between species could be measured by comparing the degree
of aggregation of different species of settling larvae under uniform
experimental conditions using nearest neighbour methods (cf. Edgar
and Meadows, 1969; Campbell and Meadows, 1972), and the interaction
of gregarious responses with other aspects of larval behaviour should not
be difficult to investigate.
The large body of information on the gregarious behaviour of larvae
at settlement contrasts markedly with the little that is known of
gregariousness in adult animals. There is no reason why mobile adult
animals such as the adults of many molluscs, echinoderms and
crustaceans should not be gregarious, but they have not as yet attracted
much attention.
Similarly, little is known of any gregarious
tendencies amongst the young of such groups as the free-living
nematodes, viviparous echinoderms, or amphipod and isopod Crustacea,
in which there is no larval stage and therefore no metamorphosis, and
in which the young bear a strong resemblance to the adult (Sheader
and Chia, 1970). Let us now, therefore, consider the evidence for
gregarious behaviour by adult animals.
The only records of gregarious behaviour in adult planktonic animals
are those of Bainbridge (1952) on Calanus and of Clutter (1969) on
mysids. Both authors describe swarms in the sea ranging in size
from about 12 individuals (Calanus) to more than 1000 individuals
(mysids). Clutter concludes from his experiments that mysid swarms
are maintained by visual clues during the day and perhaps by body
contact and swimming currents in darkness.
Little is known of gregarious behaviour by adult sublittoral animals
living in or on sediments, although the observations of divers imply it
may be fairly general. The spider crab Maia s q u i d 0 (Herbst) forms
heaps or pods of about 1 m diameter and 0.6 m high in which there may