24
suitable dens or other shelter (Mather 1991b; Forsythe and Hanlon 1997; Scheel
and Bisson 2012; Smith 2012). Different species may forage at intervals from several times per day ( E� dofleini: Mather et al. 1985; O� vulgaris: Mather 1991a) to
every 2–3 days ( E� dofleini: Scheel and Bisson 2012). Foraging trip lengths are
generally small, extending no more than 30–57 m from a den for large species ( O�
cyanea: Ivey 2007; E� dofleini: Scheel and Bisson 2012) and to only 6 m for O�
vulgaris (Mather 1994).
Octopuses and cuttlefish will take prepared foods, and there has been some effort to create prepared diets of both natural (e.g. shrimp, squid) and terrestrial (e.g.
chicken) foods for rearing cephalopods in captivity (Lee et al. 1991; Lee 1994;
Garcia et al. 2011; Rosas et al. 2011), with more recent work showing increased
promise for solving this difficult problem. Although both cuttlefish and octopuses
grew on prepared diets, in all cases growth rates were below those on natural foods,
and in many cases cuttlefish and octopuses on prepared diets did not grow (Lee
et al. 1991; Domingues et al. 2007; Domingues et al. 2008; Valverde et al. 2008;
Rosas et al. 2011). Cuttlefish eating prepared foods exhibited lower assimilation
efficiencies than on natural foods (Rosas et al. 2007), possibly in part due to interference with digestion by binders used in prepared foods (Rosas et al. 2008; Garcia
et al. 2011). Live foods, especially for early developmental stages, continue to have
more success than prepared diets. However, both cuttlefish and octopuses can readily be trained to take minimally processed but nonliving marine foods, such as fresh
or frozen fish, squid, or shrimp (e.g. Koueta et al. 2006). Octopus growth rates may
be higher on mixed than monotypic diets (Rigby and Sakurai 2004), and nutrition
ratios may be important in maximizing growth (Lee 1994; Aguila et al. 2007; Onthank and Cowles 2011) although this remains poorly understood.
2.4 Nonsexual Social Interactions
A generalization that cephalopods are solitary outside of the reproductive period
would be true, with small exceptions and some variation (Boal 2006). With a semelparous life history (see below), the presence of parental care only in the octopuses and a fairly complete lack of overlap of generations, cephalopods are not
likely to have been selected for social behaviour. Cooperation would be selected for
by three different mechanisms (Drickamer et al. 1996). One is mutualism, the benefit of interactions to both individuals, which is unlikely unless animal live in close
proximity, like the squid. A second is kin selection, again unlikely when planktonic
dispersal means that most cephalopods are not living near kin. A third is reciprocity,
where one individual benefits another, expecting a future benefit, and again this is
unlikely in animals such as cephalopods that avoid one another much of their lifetime. Nevertheless, social recognition occurs in some cephalopods (Boal 2006) and
other social behaviours may occur but have yet to be carefully studied.
Outside of the reproductive period, cuttlefish may be solitary, although field data
(Corner and Moore 1980) are fragmentary, and reproductive social tactics may have
J. Mather and D. Scheel
suitable dens or other shelter (Mather 1991b; Forsythe and Hanlon 1997; Scheel
and Bisson 2012; Smith 2012). Different species may forage at intervals from several times per day ( E� dofleini: Mather et al. 1985; O� vulgaris: Mather 1991a) to
every 2–3 days ( E� dofleini: Scheel and Bisson 2012). Foraging trip lengths are
generally small, extending no more than 30–57 m from a den for large species ( O�
cyanea: Ivey 2007; E� dofleini: Scheel and Bisson 2012) and to only 6 m for O�
vulgaris (Mather 1994).
Octopuses and cuttlefish will take prepared foods, and there has been some effort to create prepared diets of both natural (e.g. shrimp, squid) and terrestrial (e.g.
chicken) foods for rearing cephalopods in captivity (Lee et al. 1991; Lee 1994;
Garcia et al. 2011; Rosas et al. 2011), with more recent work showing increased
promise for solving this difficult problem. Although both cuttlefish and octopuses
grew on prepared diets, in all cases growth rates were below those on natural foods,
and in many cases cuttlefish and octopuses on prepared diets did not grow (Lee
et al. 1991; Domingues et al. 2007; Domingues et al. 2008; Valverde et al. 2008;
Rosas et al. 2011). Cuttlefish eating prepared foods exhibited lower assimilation
efficiencies than on natural foods (Rosas et al. 2007), possibly in part due to interference with digestion by binders used in prepared foods (Rosas et al. 2008; Garcia
et al. 2011). Live foods, especially for early developmental stages, continue to have
more success than prepared diets. However, both cuttlefish and octopuses can readily be trained to take minimally processed but nonliving marine foods, such as fresh
or frozen fish, squid, or shrimp (e.g. Koueta et al. 2006). Octopus growth rates may
be higher on mixed than monotypic diets (Rigby and Sakurai 2004), and nutrition
ratios may be important in maximizing growth (Lee 1994; Aguila et al. 2007; Onthank and Cowles 2011) although this remains poorly understood.
2.4 Nonsexual Social Interactions
A generalization that cephalopods are solitary outside of the reproductive period
would be true, with small exceptions and some variation (Boal 2006). With a semelparous life history (see below), the presence of parental care only in the octopuses and a fairly complete lack of overlap of generations, cephalopods are not
likely to have been selected for social behaviour. Cooperation would be selected for
by three different mechanisms (Drickamer et al. 1996). One is mutualism, the benefit of interactions to both individuals, which is unlikely unless animal live in close
proximity, like the squid. A second is kin selection, again unlikely when planktonic
dispersal means that most cephalopods are not living near kin. A third is reciprocity,
where one individual benefits another, expecting a future benefit, and again this is
unlikely in animals such as cephalopods that avoid one another much of their lifetime. Nevertheless, social recognition occurs in some cephalopods (Boal 2006) and
other social behaviours may occur but have yet to be carefully studied.
Outside of the reproductive period, cuttlefish may be solitary, although field data
(Corner and Moore 1980) are fragmentary, and reproductive social tactics may have
J. Mather and D. Scheel