21
octopuses typically do, or in aggregate, as may squid (Neill and Cullen 1974; Boal
2006), although many schooling squid forage solitarily at night. The coleoid cephalopods are visually guided predators, although octopuses may also forage tactilely
(for review, see Hanlon and Messenger 1996). For many cephalopods, hard remains
of prey—from stomach contents for squid and from midden piles outside the den for
octopuses—provide information about diet composition. Diet remains much less
well known from deep water species, away from dens, or from soft prey whose
remains are not found in middens or stomach, although that is changing as information from molecular methods becomes available (e.g. Lorrain et al. 2011). However,
in such cases, molecular data have confirmed that descriptions of diet content from
hard remains include the majority of cephalopod prey (e.g. Stowasser et al. 2006;
Hunsicker et al. 2010; Lorrain et al. 2011), although some molecular methods may
provide greater temporal detail (e.g. Hunsicker et al. 2010).
2.3.1 Cuttlefish (Order Sepiida) and Squid (Order Teuthida)
The main foods of cuttlefish and squid are shrimp, crab, and fish, but they also
are known to consume other crustaceans (euphasiids, copepods, cirripedes, amphipods), some molluscs (including gastropods, bivalves, and cephalopods), as well
as polychaetes (Hanlon and Messenger 1996). Knowledge of squid-feeding ecology is limited (Lorrain et al. 2011). Squid are active predators whose total dietary
composition is broad and varies with growth. Among Illex argentinus individuals, 55–85 % included crustaceans in their diet, mainly Themisto gaudichaudii (order Amphipoda) and euphasiids, while the occurrence of squid was 12–13 %, and
3–29 % of squid individuals consumed fish (Ivanovich and Brunetti 1994). Similarly, diets of common Atlantic squid I� illecebrosus and Doryteuthis ( Loligo) pealeii
were diverse, and while that of I� illecebrosus was dominated by fishes, squid, and
non-decapod crustaceans, the stomach contents of D� pealeii consisted of largely
unidentified prey remains, molluscs, and copepods (Bowman et al. 2000). Cannibalism occurs commonly and is increased by crowding (Ivanovich and Brunetti
1994; Ibáñez and Keyl 2010). Many squid are harvested by jigging (e.g. Chen et al.
2008) possibly indicating attacks to a wide range of stimuli that may contribute to
a broad diet.
Both cuttlefish and squid attack prey in stages consisting of attention behaviours,
a positioning approach, and ambush-like strike in which the long tentacles shoot out
to seize the prey (Messenger 1968; Neill and Cullen 1974). The attention behaviours involve changes in body patterning, arm positioning, and orientation of the
body towards the prey (Messenger 1968). For slower moving prey (such as crabs)
of both squid and cuttlefish, approach occurs only from behind the prey, and seizure
occurs with partially opened arms without use of the tentacles (Duval et al. 1984).
There is little work on the behavioural ecology of squid and cuttlefish diet choice,
and these groups are considered predatory generalists (e.g. Guerra 2006). However,
cuttlefish have been an important invertebrate model system to understand learning
in the context of the ontogeny of hunting behaviour and prey choice (e.g. Messenger
2 Behaviour
octopuses typically do, or in aggregate, as may squid (Neill and Cullen 1974; Boal
2006), although many schooling squid forage solitarily at night. The coleoid cephalopods are visually guided predators, although octopuses may also forage tactilely
(for review, see Hanlon and Messenger 1996). For many cephalopods, hard remains
of prey—from stomach contents for squid and from midden piles outside the den for
octopuses—provide information about diet composition. Diet remains much less
well known from deep water species, away from dens, or from soft prey whose
remains are not found in middens or stomach, although that is changing as information from molecular methods becomes available (e.g. Lorrain et al. 2011). However,
in such cases, molecular data have confirmed that descriptions of diet content from
hard remains include the majority of cephalopod prey (e.g. Stowasser et al. 2006;
Hunsicker et al. 2010; Lorrain et al. 2011), although some molecular methods may
provide greater temporal detail (e.g. Hunsicker et al. 2010).
2.3.1 Cuttlefish (Order Sepiida) and Squid (Order Teuthida)
The main foods of cuttlefish and squid are shrimp, crab, and fish, but they also
are known to consume other crustaceans (euphasiids, copepods, cirripedes, amphipods), some molluscs (including gastropods, bivalves, and cephalopods), as well
as polychaetes (Hanlon and Messenger 1996). Knowledge of squid-feeding ecology is limited (Lorrain et al. 2011). Squid are active predators whose total dietary
composition is broad and varies with growth. Among Illex argentinus individuals, 55–85 % included crustaceans in their diet, mainly Themisto gaudichaudii (order Amphipoda) and euphasiids, while the occurrence of squid was 12–13 %, and
3–29 % of squid individuals consumed fish (Ivanovich and Brunetti 1994). Similarly, diets of common Atlantic squid I� illecebrosus and Doryteuthis ( Loligo) pealeii
were diverse, and while that of I� illecebrosus was dominated by fishes, squid, and
non-decapod crustaceans, the stomach contents of D� pealeii consisted of largely
unidentified prey remains, molluscs, and copepods (Bowman et al. 2000). Cannibalism occurs commonly and is increased by crowding (Ivanovich and Brunetti
1994; Ibáñez and Keyl 2010). Many squid are harvested by jigging (e.g. Chen et al.
2008) possibly indicating attacks to a wide range of stimuli that may contribute to
a broad diet.
Both cuttlefish and squid attack prey in stages consisting of attention behaviours,
a positioning approach, and ambush-like strike in which the long tentacles shoot out
to seize the prey (Messenger 1968; Neill and Cullen 1974). The attention behaviours involve changes in body patterning, arm positioning, and orientation of the
body towards the prey (Messenger 1968). For slower moving prey (such as crabs)
of both squid and cuttlefish, approach occurs only from behind the prey, and seizure
occurs with partially opened arms without use of the tentacles (Duval et al. 1984).
There is little work on the behavioural ecology of squid and cuttlefish diet choice,
and these groups are considered predatory generalists (e.g. Guerra 2006). However,
cuttlefish have been an important invertebrate model system to understand learning
in the context of the ontogeny of hunting behaviour and prey choice (e.g. Messenger
2 Behaviour