19
2 Behaviour
2003a, b) but descriptions of the rest of their behavioural repertoire are lacking.
Many cephalopods are nocturnally active and their activity cycle is not flexible
(Meisel et al. 2006), though again O� vulgaris is the exception. The behaviour of
nocturnal animal is difficult to study, as shining a light on them can change their
behaviour and few scientists have a night-viewing system that works in the water.
Nevertheless, the behaviour of cephalopods can reveal basic adaptations to the
necessities of life. The first necessity is adapting to the physical, chemical, and biological environment around them, including predators. Although predators may be
absent in a laboratory environment, antipredator reactions such as inking will still
be present. The second necessity is provision of food, and although the laboratory
environment may provide food easily, there are the problems of appropriate diet,
food preparation, and enrichment with food provision for young. A third necessity is relationship with conspecifics; although many of the cephalopods are not
social (Boal 2006), this can bring problems for confinement itself, such as cannibalism (Ibáñez and Keyl 2010). A fourth necessity is provision of opportunities
for reproduction, from the stage of mating through guarding of eggs in octopuses
to the provision of a proper environment for planktonic paralarvae (see Chap. 23).
Understanding these problems can lead to providing an enriched environment for
cephalopods in captivity. Enrichment of the captive environment is not just window-dressing for aquarium audiences (Peters et al. 2005). Cuttlefish raised in an
enriched environment grow faster and learn better (Dickel et al. 2000) and habitat
enrichment increases the activity and widens the range of skin patterns in mudflat
octopuses (Biegel and Boal 2006). This is particularly important for development,
as young cuttlefish given a complex background learn to produce skin patterns and
dig in the sand more quickly (Poirier et al. 2004, 2005). Taking these aspects of
biology into consideration, Moltschaniwskyj et al. (2007) have written a thorough
review of ethical and welfare considerations when keeping cephalopods.
2.2 Antipredator Behaviours
Without the protection of the molluscan shell, cephalopods are at risk for predation,
particularly from fish (Packard 1972). They have evolved a galaxy of antipredator
responses, including skin displays mediated by the complex chromatophore system
(Messenger 2001). Excellent bottom-matching camouflage (Hanlon and Messenger
1988) is a specialty of the cuttlefish and this matching has been used to investigate
the ability of the cephalopod visual system to analyse its environment (e.g. Barbosa
et al. 2008). Young nektonic squid such as S� sepioidea use a variety of patterns
accompanied by postures to match features of their environment (Moynihan and
Rodaniche 1977; Mather et al. 2010b). In the open water, many squid and cuttlefish use reflexive countershading for camouflage from predators above or below
(Ferguson et al. 1994). On the approach of a potential predator, cephalopods of all
groups use startle deimatic displays with eyespots (Langridge et al. 2007; Mather
2010; Staudinger et al. 2012). These are selectively used in the presence of visual
2 Behaviour
2003a, b) but descriptions of the rest of their behavioural repertoire are lacking.
Many cephalopods are nocturnally active and their activity cycle is not flexible
(Meisel et al. 2006), though again O� vulgaris is the exception. The behaviour of
nocturnal animal is difficult to study, as shining a light on them can change their
behaviour and few scientists have a night-viewing system that works in the water.
Nevertheless, the behaviour of cephalopods can reveal basic adaptations to the
necessities of life. The first necessity is adapting to the physical, chemical, and biological environment around them, including predators. Although predators may be
absent in a laboratory environment, antipredator reactions such as inking will still
be present. The second necessity is provision of food, and although the laboratory
environment may provide food easily, there are the problems of appropriate diet,
food preparation, and enrichment with food provision for young. A third necessity is relationship with conspecifics; although many of the cephalopods are not
social (Boal 2006), this can bring problems for confinement itself, such as cannibalism (Ibáñez and Keyl 2010). A fourth necessity is provision of opportunities
for reproduction, from the stage of mating through guarding of eggs in octopuses
to the provision of a proper environment for planktonic paralarvae (see Chap. 23).
Understanding these problems can lead to providing an enriched environment for
cephalopods in captivity. Enrichment of the captive environment is not just window-dressing for aquarium audiences (Peters et al. 2005). Cuttlefish raised in an
enriched environment grow faster and learn better (Dickel et al. 2000) and habitat
enrichment increases the activity and widens the range of skin patterns in mudflat
octopuses (Biegel and Boal 2006). This is particularly important for development,
as young cuttlefish given a complex background learn to produce skin patterns and
dig in the sand more quickly (Poirier et al. 2004, 2005). Taking these aspects of
biology into consideration, Moltschaniwskyj et al. (2007) have written a thorough
review of ethical and welfare considerations when keeping cephalopods.
2.2 Antipredator Behaviours
Without the protection of the molluscan shell, cephalopods are at risk for predation,
particularly from fish (Packard 1972). They have evolved a galaxy of antipredator
responses, including skin displays mediated by the complex chromatophore system
(Messenger 2001). Excellent bottom-matching camouflage (Hanlon and Messenger
1988) is a specialty of the cuttlefish and this matching has been used to investigate
the ability of the cephalopod visual system to analyse its environment (e.g. Barbosa
et al. 2008). Young nektonic squid such as S� sepioidea use a variety of patterns
accompanied by postures to match features of their environment (Moynihan and
Rodaniche 1977; Mather et al. 2010b). In the open water, many squid and cuttlefish use reflexive countershading for camouflage from predators above or below
(Ferguson et al. 1994). On the approach of a potential predator, cephalopods of all
groups use startle deimatic displays with eyespots (Langridge et al. 2007; Mather
2010; Staudinger et al. 2012). These are selectively used in the presence of visual