Transcript Cephalopods - GMCbiology

Cephalopods
General Characteristics
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Cephalopoda means "head foot"
– Cephalopods are characterized by a completely merged
head and foot
Octopuses, squids, cuttlefish, and chambered nautiluses
Well developed head
Prominent foot divided into tentacles
Free swimming
Predatory - carnivorous
Strong suckers
A cephalopod is also characterized by a horny beak secreted
by the walls of the buccal cavity, and a radula within the
buccal cavity.
The digestive tract consists of three parts: esophagus ,
which may contain a crop; stomach , which mashes food;
and caecum , where most digestion and absorption occur
Characteristics
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Closed circulatory system
– Blood circulates entirely within blood vessels
– Allows for high metabolic rate
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Reproduction
– A female typically possesses a single oviduct. A male
produces spermatophores that it transfers to the
female's genital pore by means of a specialized arm or
tentacle. In some species, the specialized arm tip may
be pinched off and left in the female's mantle cavity
– Mating in some cephalopods includes courtship rituals
that may consist of color changes, body movements, or
combinations of both.
Squid
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Marine
Largest invertebrate (20 M; 3,360 Kg)
Large complex brain
Highly developed nervous system
Large pair of vertebrate like eyes
Two Tentacles and Eight Arms
– Tentacles are used to capture prey
– Arms force prey into mouth
Squid
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Muscular mantel
propels by pumping water through siphon
– Jet Propulsion
– a very energy-consuming way to travel
compared to the tail propulsion used by fish
 This inefficiency in locomotion worsens
as the size of the species increases
 This is probably the reason why many
species will use their fins or arms for
locomotion if possible
– can move short distances in any direction by
rippling of a flap of muscle around the mantle
Excrete inky substance when threatened
Chromatophores - change color
– Used for communication and camouflage
Squid
 Internal
fertilization
–Lay mass of gelatinous
encased eggs
–Maternal protection
until hatching
Cuttlefish
 Cuttlefish
have an
internal shell (the cuttlebone)
 large W-shaped pupils
 eight arms & two tentacles furnished
with denticulated suckers, with which
they secure their prey.
Cuttlefish
Their life expectancy is about one to two
years.
 Recent studies indicate that cuttlefish are
among the most intelligent invertebrates.
 Cuttlefish also have one of the largest
brain-to-body size ratios of all
invertebrates.
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Octopuses
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The Common Octopus reaches 24 – 36 inches in
length.
Habitat - The Common Octopus is found world-wide in
tropical, subtropical and temperate waters. It prefers
coastal waters, and can live both in the shallows and
down to a depth of 500 feet
The skin is smooth and has special pigment cells,
chromatophores, that make it possible for the
octopus to blend in with the surroundings
(camouflage).
– Coloration can also reflect its mood.
– White is for fear, red is for anger
and brown is the usual color.
lack any internal shell
Octopuses
The Common Octopus is normally solitary
and territorial. It finds a home in a cavity
or digs a burrow for itself, and leaves it
only to feed or reproduce. They often
protect and hide their homes with shells,
stones and other solid things that they
gather.
 The Common Octopus is an active
nocturnal predator that feeds mainly on
crustaceans, fish and bivalves.
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Octopuses
 Octopuses
have the
most complex brain of all
the invertebrates . Just
like vertebrates, they
have long term and
short-term memories
– They learn to solve
problems by trial-anderror and experience
Chambered Nautilus
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Most primitive of the Cephalopods
Size – 8 to 10 inches
Found in the Indian and Pacific Oceans down to
1800 feet in tropical regions
The chambered nautilus is an example of an a
living fossil, it has remained unchanged for over
400 million years
Jet propulsion propels the nautilus in the opposite
direction at high speeds.
Nocturnal
Chambered Nautilus
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The shell of the nautilus is comprised of many
individual chambers. Each chamber is individually
sealed and contains an amount of gas.
– This provides the animal with buoyancy.
– The nautilus can regulate its density by
injecting or removing fluid into these chambers
through a system of tubes.