Ch. 6— Alternatives to Animal Use in Research • 129 
Aggression 
Aggressive interactions between members of the 
same species have been studied in a variety of fish 
and reptile species under both laboratory and field 
conditions. Considerable work has been done on 
intermale rivalry among stickleback (183) and cich- 
lid fish (11). Aggressive interactions among cold- 
blooded vertebrates are frequently stereotyped 
and species-specific. Among stickleback fish, for 
example, full-fledged attacks can be elicited by a 
model that is the same color but a different shape 
(30). In contrast, aggression in primates can em- 
body a variety of highly sophisticated introspec- 
tive social strategies such as deception, grudging, 
delayed retaliation, and reconciliation (77). Thus 
extrapolation among all vertebrates of the results 
of research into aggression is difficult. 
Animal Movements 
Migration and homing abilities have been inten- 
sively studied in several species of fish, particu- 
larly eels and Pacific salmon. Among American and 
European eels, for example, the eggs hatch in the 
Sargasso Sea, near Bermuda. The juvenile fish 
make a year-long migration toward the coasts of 
North America and Europe. On reaching sexual 
maturity in 7 to 15 years, the adult eels migrate 
back to the Sargasso Sea to breed (217), a move- 
ment primarily dependent on the use of chemical 
cues in the water (60). In contrast, birds use solar, 
stellar, and magnetic cues to navigate, and whales 
use the topography of the ocean floor and coast- 
line to remain on course for migratory purposes. 
Such dramatic differences in the way different spe- 
cies respond to and perceive the environment limit 
the use of cold-blooded vertebrates in modeling 
animal movements of warm-blooded ones. 
Communication 
Visual cues, such as changes in coloration, pos- 
ture, or body appearance, have been shown to 
be important determinants of social interaction 
among fish (30), which, unlike most mammals, gen- 
erally have color vision. Fish also exhibit dramatic 
changes in appearance, such as flaring of the gill 
apertures, which are relatively rare among mam- 
mals. Auditory communication is marked by spe- 
cies differences, too. Communication among am- 
phibians and reptiles, primarily to attract a mate, 
consists of simple one- or two-note utterances. 
Vocalization in birds and mammals consists of a 
wide range and variety of sounds. Moreover, un- 
like cold-blooded species, many birds have to learn 
species -specific songs. Many rodents communicate 
by ultrasonic vocalizations (123) that have no ap- 
parent counterpart among cold-blooded species. 
Learning, Memory, and 
Problem Solving 
Learning has been studied in a variety of diverse 
species (179,183), and many differences are mani- 
fested. Comparing learning in goldfish and turtles 
with that in rats yields both similar and distinguish- 
ing features. For example, rats show a decrement 
in performance when an accustomed reward is 
changed, while goldfish and turtles do not (23). 
The existence of so-called biological boundaries 
of learning (182), apparently shaped by unique eco- 
logical pressures, precludes most substitutions of 
one species for another in learning paradigms. 
Predator-Prey Relations 
Prey -catching behavior and predator avoidance 
have been studied in fish, frogs, and turtles (60, 
103,203). The similarity across species in behaviors 
used by prey to avoid being caught suggests that 
when a general question about reactions to pre- 
dation (rather than the behavior of a given spe- 
cies) is of interest, cold-blooded vertebrates can 
substitute for warm-blooded ones (103). But there 
is growing evidence of neurochemical differences 
underlying predator avoidance behaviors even 
among birds and mammals (78). 
Predators exhibit marked differences across spe- 
cies. Frogs, for example, sit passively and wait for 
an insect to come within striking distance, while 
some carnivores have developed sophisticated 
hunting strategies that often embody elements of 
cooperation and may even culminate in sharing 
foods (30). 
Reproduction and Parental Care 
With some notable exceptions (e.g., the African 
Mouthbreeder fish), parental care of offspring is 
absent in most cold-blooded vertebrates, since the 
eggs are typically abandoned shortly after fertili- 
