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3.2.3 Octopuses
3.2.3.1 General Information About Octopuses
Octopuses are members of the Cephalopoda class of molluscs. They are in the
Octopodidae family and most of the species are placed in the genus Octopus. The
life span of octopuses varies with species from about 6 months to 3–5 years.
Octopuses are found in many diverse habitats, including rocks, kelp holdfasts, and
soft bottom substrates such as sand and mud. Most octopuses live in rocky areas
where small caves, crevices, and rocks serve as dens or homes. Some species live in
sandy areas and apparently do not have permanent homes. Octopuses are thought to
be territorial because some individuals are known to defend their territory against
other octopuses entering their area. They feed on crustaceans, other molluscs, and
small fishes. Some species feed exclusively at night, while others are only active
during the day or at dawn or dusk (Price 2000).
As the name suggests, the species in this group have eight legs or arms lined up
around the head. On the inner surface of these arms, there are suckers providing
them adhering to prey animals or hard objects. Octopuses do not have fins, and
some species have thin membrane skin connections on the bottom of the arms. The
body is spherical. His arms are longer than his body. They are bottom-living molluscs with moderate swimming ability.
Like most other cephalopods, octopuses have a relatively short life span (usually
6 months to 4 years, depending on the species), though there is strong evidence that
deep-sea species live longer. Most species are semelparous, having one reproductive event near the end of life. Mating occurs opportunistically throughout life but is
reported to be more frequent as the end of the lifespan approaches. Octopuses are
typically crepuscular hunters, leaving their dens at dawn and dusk to survey their
feeding territories and speculatively pounce on likely prey locations. Octopuses
largely prefer crustacean prey, but they are highly opportunistic and also known to
consume fish, polychaetes, chaetognaths, echinoderms and other cephalopods.
Octopuses contain no hard parts in their bodies except for a beak and a radula.
Similar to other cephalopods, but to a more extreme degree, the octopus also possesses a cartilaginous “skull” surrounding and enveloping the great majority of the
central nervous system. Since there is no rigid skeleton, bodily support and movement are accomplished via muscular hydrostat. This mechanism is especially
important to the movement of octopus arms. In the arms, four different bundles of
muscle are recognized: longitudinal, transverse, circular, and oblique. These provide support and contract against each other to allow a large variety of movements.
The arms of the octopus are incredibly flexible and strong, with unlimited degrees
of freedom and the ability to bend at any point. They originate from the area around
the mouth (the brachial crown) and serve a variety of purposes for the animal,
including searching in crevices for prey, capturing prey, transferring food to the
mouth, exploring their surroundings, certain forms of locomotion, self-cleaning,
intra- and inter-specific signalling, mating and defence against predators. Another
3.2 Cephalopods
3.2.3 Octopuses
3.2.3.1 General Information About Octopuses
Octopuses are members of the Cephalopoda class of molluscs. They are in the
Octopodidae family and most of the species are placed in the genus Octopus. The
life span of octopuses varies with species from about 6 months to 3–5 years.
Octopuses are found in many diverse habitats, including rocks, kelp holdfasts, and
soft bottom substrates such as sand and mud. Most octopuses live in rocky areas
where small caves, crevices, and rocks serve as dens or homes. Some species live in
sandy areas and apparently do not have permanent homes. Octopuses are thought to
be territorial because some individuals are known to defend their territory against
other octopuses entering their area. They feed on crustaceans, other molluscs, and
small fishes. Some species feed exclusively at night, while others are only active
during the day or at dawn or dusk (Price 2000).
As the name suggests, the species in this group have eight legs or arms lined up
around the head. On the inner surface of these arms, there are suckers providing
them adhering to prey animals or hard objects. Octopuses do not have fins, and
some species have thin membrane skin connections on the bottom of the arms. The
body is spherical. His arms are longer than his body. They are bottom-living molluscs with moderate swimming ability.
Like most other cephalopods, octopuses have a relatively short life span (usually
6 months to 4 years, depending on the species), though there is strong evidence that
deep-sea species live longer. Most species are semelparous, having one reproductive event near the end of life. Mating occurs opportunistically throughout life but is
reported to be more frequent as the end of the lifespan approaches. Octopuses are
typically crepuscular hunters, leaving their dens at dawn and dusk to survey their
feeding territories and speculatively pounce on likely prey locations. Octopuses
largely prefer crustacean prey, but they are highly opportunistic and also known to
consume fish, polychaetes, chaetognaths, echinoderms and other cephalopods.
Octopuses contain no hard parts in their bodies except for a beak and a radula.
Similar to other cephalopods, but to a more extreme degree, the octopus also possesses a cartilaginous “skull” surrounding and enveloping the great majority of the
central nervous system. Since there is no rigid skeleton, bodily support and movement are accomplished via muscular hydrostat. This mechanism is especially
important to the movement of octopus arms. In the arms, four different bundles of
muscle are recognized: longitudinal, transverse, circular, and oblique. These provide support and contract against each other to allow a large variety of movements.
The arms of the octopus are incredibly flexible and strong, with unlimited degrees
of freedom and the ability to bend at any point. They originate from the area around
the mouth (the brachial crown) and serve a variety of purposes for the animal,
including searching in crevices for prey, capturing prey, transferring food to the
mouth, exploring their surroundings, certain forms of locomotion, self-cleaning,
intra- and inter-specific signalling, mating and defence against predators. Another
3.2 Cephalopods