CephalopodsCephalopods

General CharacteristicsGeneral Characteristics Cephalopoda means "head foot" Cephalopoda means "head foot"

– Cephalopods are characterized by a completely merged Cephalopods are characterized by a completely merged head and foot head and foot

Octopuses, squids, cuttlefish, and chambered nautiluses Octopuses, squids, cuttlefish, and chambered nautiluses Well developed head Well developed head Prominent foot divided into tentacles Prominent foot divided into tentacles Free swimming Free swimming Predatory - carnivorousPredatory - carnivorous Strong suckers Strong suckers A cephalopod is also characterized by a horny beak secreted A cephalopod is also characterized by a horny beak secreted

by the walls of the buccal cavity, and a radula within the by the walls of the buccal cavity, and a radula within the buccal cavity. buccal cavity.

The digestive tract consists of three parts: The digestive tract consists of three parts: esophagus , , which may contain a crop; which may contain a crop; stomach , which mashes food; , which mashes food; and and caecum , where most digestion and absorption occur , where most digestion and absorption occur

CharacteristicsCharacteristics Closed circulatory system Closed circulatory system

– Blood circulates entirely within blood vessels Blood circulates entirely within blood vessels – Allows for high metabolic rate Allows for high metabolic rate

ReproductionReproduction– A female typically possesses a single oviduct. A male A female typically possesses a single oviduct. A male

produces spermatophores that it transfers to the produces spermatophores that it transfers to the female's genital pore by means of a specialized arm or female's genital pore by means of a specialized arm or tentacle. In some species, the specialized arm tip may tentacle. In some species, the specialized arm tip may be pinched off and left in the female's mantle cavity be pinched off and left in the female's mantle cavity

– Mating in some cephalopods includes courtship rituals Mating in some cephalopods includes courtship rituals that may consist of color changes, body movements, or that may consist of color changes, body movements, or combinations of both. combinations of both.

SquidSquid Marine Marine Largest invertebrate (20 M; 3,360 Kg) Largest invertebrate (20 M; 3,360 Kg) Large complex brain Large complex brain Highly developed nervous system Highly developed nervous system Large pair of vertebrate like eyes Large pair of vertebrate like eyes Two Tentacles and Eight Arms Two Tentacles and Eight Arms

– Tentacles are used to capture prey Tentacles are used to capture prey – Arms force prey into mouth Arms force prey into mouth

SquidSquid Muscular mantel Muscular mantel propels by pumping water through siphon propels by pumping water through siphon

– Jet PropulsionJet Propulsion– a very energy-consuming way to travel a very energy-consuming way to travel

compared to the tail propulsion used by fish compared to the tail propulsion used by fish This inefficiency in locomotion worsens This inefficiency in locomotion worsens

as the size of the species increasesas the size of the species increasesThis is probably the reason why many This is probably the reason why many

species will use their fins or arms for species will use their fins or arms for locomotion if possible locomotion if possible

– can move short distances in any direction by can move short distances in any direction by rippling of a flap of rippling of a flap of muscle around the mantle around the mantle

Excrete inky substance when threatened Excrete inky substance when threatened Chromatophores - change color Chromatophores - change color

– Used for communication and camouflageUsed for communication and camouflage

SquidSquid

Internal fertilization Internal fertilization – Lay mass of gelatinous Lay mass of gelatinous

encased eggs encased eggs – Maternal protection Maternal protection

until hatchinguntil hatching

CuttlefishCuttlefish 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.

CuttlefishCuttlefish 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.

OctopusesOctopuses The Common Octopus reaches 24 – 36 inches in The Common Octopus reaches 24 – 36 inches in

length. length. Habitat - The Common Octopus is found world-wide in Habitat - The Common Octopus is found world-wide in

tropical, subtropical and tropical, subtropical and temperate waters. It prefers waters. It prefers coastal waters, and can live both in the shallows and coastal waters, and can live both in the shallows and down to a depth of 500 feetdown to a depth of 500 feet

The skin is smooth and has special pigment cells, The skin is smooth and has special pigment cells, chromatophores, that make it possible for the chromatophores, that make it possible for the octopus to blend in with the surroundings octopus to blend in with the surroundings (camouflage). (camouflage). – Coloration can also reflect its mood.Coloration can also reflect its mood.– White is for fear, red is for angerWhite is for fear, red is for anger and brown is the usual color. and brown is the usual color.

lack any internal shell lack any internal shell

OctopusesOctopuses

The Common Octopus is normally The Common Octopus is normally solitary and territorial. It finds a home in a cavity and territorial. It finds a home in a cavity or digs a burrow for itself, and leaves it or digs a burrow for itself, and leaves it only to feed or reproduce. They often only to feed or reproduce. They often protect and hide their homes with shells, protect and hide their homes with shells, stones and other solid things that they stones and other solid things that they gather. gather.

The Common Octopus is an active The Common Octopus is an active nocturnal nocturnal predator that feeds mainly on that feeds mainly on crustaceans, fish and bivalves. crustaceans, fish and bivalves.

OctopusesOctopuses Octopuses have the Octopuses have the

most complex brain of all most complex brain of all the invertebrates . Just the invertebrates . Just like vertebrates, they like vertebrates, they have long term and have long term and short-term memories short-term memories – They learn to solve They learn to solve

problems by trial-and-problems by trial-and-error and experience error and experience

Chambered NautilusChambered Nautilus Most primitive of the CephalopodsMost primitive of the Cephalopods Size – 8 to 10 inchesSize – 8 to 10 inches Found in the Indian and Pacific Oceans down to Found in the Indian and Pacific Oceans down to

1800 feet in tropical regions1800 feet in tropical regions The chambered nautilus is an example of an a The chambered nautilus is an example of an a

living fossil, it has remained unchanged for over living fossil, it has remained unchanged for over 400 million years 400 million years

Jet propulsion propels the nautilus in the opposite Jet propulsion propels the nautilus in the opposite direction at high speeds. direction at high speeds.

NocturnalNocturnal

Chambered NautilusChambered Nautilus The shell of the nautilus is comprised of many The shell of the nautilus is comprised of many

individual chambers. Each chamber is individually individual chambers. Each chamber is individually sealed and contains an amount of gas. sealed and contains an amount of gas. – This provides the animal with buoyancy.This provides the animal with buoyancy.– The nautilus can regulate its density by The nautilus can regulate its density by

injecting or removing fluid into these chambers injecting or removing fluid into these chambers through a system of tubes.through a system of tubes.