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Cognitive Abilities of Marine Mammals
Gordon B. Bauer

Scientific studies of dolphins (order: Cetacea) behaviourally testing sensory processes, so
and sea lions (order: Pinnipedia) reveal a psychophysical reports of sensory detection
constellation of sophisticated cognitive abili- and discrimination imply discrimination
ties, including imitation, learning set acquisi- learning abilities, an important cognitive
tion, sequence learning, problem solving, trait. Bottlenose dolphins, hereafter referred
and concept learning. Manatees (order: to simply as dolphins, have exquisite hearing
Sirenia) are the only marine mammal herbi- abilities including high frequency hearing
vores and reveal an interesting set of sensory extending well into the ultrasound range
processes, although little is known about (Johnson 1967) auditory temporal process-
their broader cognitive abilities. These three ing abilities (Supin et al. 2001), and sensitive
orders of marine mammals consist of many discrimination of sound amplitude (Au and
species, but cognitive/perceptual studies are Hastings 2008). Their hearing is integrated
dominated by only a few, bottlenose dolphins with sound production to generate highly
(Tursiops truncatus) amongst the cetaceans, sensitive echolocation abilities (Au 1993). By
California sea lions (Zalophus californianus), typical mammalian standards, they have
amongst the pinnipeds, and West Indian good visual acuity, although modest com-
manatees (Trichechus manatus), amongst pared to primates. Their underwater and in‐
the sirenians. These species are commonly air vision brackets the United States of
found in captivity and therefore are readily America’s criterion for legal blindness
available for behavioural study. However, it (10 arc minutes); somewhat better than
needs to be recognised that these orders con- legally blind underwater and somewhat
tain diverse species from a wide range of worse in air (Herman et al. 1975). They are
habitats, which may be associated with dif- monochromats (Ahnelt and Kolb 2000) that
ferent cognitive characteristics. There is a most likely see their world in shades of grey
paucity of investigations of cognition in sev- (Madsen and Herman 1980) (but see Griebel
eral other marine mammal taxa, including and Peichel 2003 for an alternative view; col-
sea otters (Enhydra lutris) and polar bears our vision based on rod‐cone interaction).
(Ursis maritimus), so they are not discussed Dolphin sense of touch has been minimally
in this review. investigated (Dehnhardt and Mauck 2008),
Sensory perception is important for under- although morphological and physiological
standing cognition because it constrains the studies suggest that they are sensitive in the
type of information an animal has available facial, cranial, and genital regions (Ridgway
for processing. Also, discrimination learning and Carder 1990). The small size or absence
is inherent in the methodology involved in of olfactory bulbs suggest that toothed

Zoo Animal Learning and Training, First Edition. Edited by Vicky A. Melfi, Nicole R. Dorey, and Samantha J. Ward.
© 2020 John Wiley & Sons Ltd. Published 2020 by John Wiley & Sons Ltd.