<Emphasis Type="Italic">Octopus insularis</Emphasis> (Octopodidae), evidences of a specialized predator and a time-minimizing hunter |
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Authors: | Tatiana Silva Leite Manuel Haimovici Jennifer Mather |
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Institution: | 1.Departamento de Oceanografia e Limnologia,Universidade Federal do Rio Grande do Norte,Natal,Brazil;2.Departamento de Oceanografia,Laboratório de Recursos Demersais e Cefalópodes (FURG),Rio Grande,Brazil;3.Psychology Department,University of Lethbridge,Lethbridge,Canada |
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Abstract: | Shallow-water octopuses have been reported as major predators of motile species in benthonic marine communities, capturing
their prey by different foraging techniques. This study assessed for the first time the feeding ecology, foraging behavior,
and defensive strategy during foraging, including the use of body patterns, to construct a general octopus foraging strategy
in a shallow water-reef system. Octopus insularis was studied in situ using visual observations and video recordings. The diet included at least 55 species of crustaceans
(70%), bivalves (17.5%), and gastropods (12.5%); however, only four species accounted for half of the occurrences: the small
crabs Pitho sp. (26.8%) and Mithrax forceps (23.9%), the bivalve Lima lima (5.3%), and the gastropod Pisania pusio (4.9%). Poke and crawl were most frequent foraging behaviors observed in the video recordings. The foraging behaviors were
associated with environmental variables and octopus body size. The sequences of foraging behavior showed characteristics of
a tactile saltatory searching predator, as well as a visual opportunist. Body patterns showed a relationship with foraging
behavior, habitat variables, and octopus body size. Mottle was the most frequent pattern, especially during poke and crawl,
in shallower depths. Dorsal light–ventral blue green was more frequent during swimming at mid-water, and Blotch was the normal
pattern during web-over by large animals. The large proportion of two species of small crabs in den remains, the intense search
for food during short hunting trips, and the intense use of cryptic body patterns during foraging trips, suggest that this
species is a ‘time-minimizing’ forager instead of a ‘rate-maximizer’. |
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