The formation of social dominance hierarchies was studied in groups of five juvenile crayfish, 1.3-1.8 cm in length. Animals were grouped together in a small, featureless aquarium after having lived in isolation for more than a month. The occurrence of each of four behavior patterns (‘attack’, ‘approach’, ‘retreat’ and ‘escape’) was recorded for each animal, together with the frequency of encounters and the frequency of wins and losses. The frequencies of wins and losses were used to calculate the relative dominance value of each animal in the group. High levels of fighting developed immediately upon grouping the animals, and a positive feedback relationship between attacking and winning enabled one animal in each group to emerge quickly as the superdominant. If that animal was the largest, it remained as the superdominant; otherwise, it was replaced as superdominant within the first few days by the largest animal. This form of dominance hierarchy, with one superdominant and four subordinates, persisted throughout the duration of the grouping. Fighting declined over the first hour and by 24 h had dropped to low levels. After the first day, approaches were used together with attacks, and retreats replaced escapes. Attack and approach were the behavior patterns displayed most frequently by animals with high dominance values, whereas retreat and escape were performed by animals of low dominance. All these trends continued to develop over the next 2 weeks as the number of agonistic encounters declined to a low level.

REFERENCES

REFERENCES
Boyd
R.
,
Silk
J. B.
(
1983
).
A method for assigning cardinal dominance ranks
.
Anim. Behav
31
,
45
–.
Bruner
J.
,
Kennedy
D.
(
1970
).
Habituation: occurrence at a neuromuscular junction
.
Science
169
,
92
–.
Bruski
C. A.
,
Dunham
D. W.
(
1987
).
The importance of vision in agonistic communication of the crayfish Orconectes rusticus. I. An analysis of bout dynamics
.
Behaviour
103
,
83
–.
Clutton-Brock
T. H.
,
Parker
G. A.
(
1995
).
Punishment in animal societies
.
Nature
373
,
209
–.
Figler
M. H.
,
Twum
M.
,
Finkelstein
J. E.
,
Peeke
H. V. S.
(
1995
).
Maternal aggression in red swamp crayfish (Procambarus clarkii, Girard): the relation between reproductive status and outcome of aggressive encounters with male and female conspecifics
.
Behaviour
132
,
108
–.
Fuller
R. W.
(
1996
).
Fluoxetine effects on serotonin function and aggressive behavior
.
Ann. N.Y. Acad. Sci
794
,
90
–.
Huber
R.
,
Kravitz
E. A.
(
1995
).
A quantitative analysis of agonistic behavior in juvenile American lobsters (Homarus americanus L.)
.
Brain Behav. Evol
46
,
72
–.
Huber
R.
,
Smith
K.
,
Delago
A.
,
Isaksson
K.
,
Kravitz
E. A.
(
1997
).
Serotonin and aggressive motivation in crustaceans:altering the decision to retreat
.
Proc. Natl. Acad. Sci. USA
94
,
5939
–.
Krasne
F. B.
,
Shamasian
A.
,
Kulkarni
R.
(
1997
).
Altered excitability of the crayfish lateral giant escape reflex during agonistic encounters
.
J. Neurosci
17
,
692
–.
Page
T. L.
,
Larimer
J. L.
(
1972
).
Entrainment of the circadian locomotor activity rhythm in crayfish
.
J. Comp. Physiol
78
,
107
–.
Peeke
H. V. S.
,
Herz
M. J.
,
Gallagher
J. E.
(
1971
).
Changes in aggressive interaction in adjacently territorial convict cichlids (Cichlasoma nigrofasciatium): A study of habituation
.
Behaviour
40
,
43
–.
Söderbäck
B.
(
1991
).
Interspecfic dominance relationship and aggressive interactions in the freshwater crayfishes Astacus astacus L. and Pacifastacus leniusculus (Dana)
.
Can. J. Zool
69
,
1321
–.
Yeh
S. R.
,
Fricke
R. A.
,
Edwards
D. H.
(
1996
).
The effect of social experience on serotonergic modulation of the escape circuit of crayfish
.
Science
271
,
366
–.
Yeh
S. R.
,
Musolf
B. E.
,
Edwards
D. H.
(
1997
).
Neuronal adaptations to changes in the social dominance status of crayfish
.
J. Neurosci
17
,
697
–.
This content is only available via PDF.