By Sasha Georgiev

Biology 9A

Cephalopods (ii)

Belongs to phyla called mollusca cephalo+poda=head+foot Octopus, squid, cuttlefish

Phyla

About 800 classified species 11,000 extinct species Found in all oceans of earth Do not tolerate freshwater One exception Greatest diversity towards the equator Occupies abyssal plain to surface Advanced vision Good camouflage More than one heart

Specific features

Nautiloids – earliest cephalopods in fossil record Late cambrian period Simple shell shapes

Fossils

Ocassionally long lived Mostly short life spam Gain 12 percent body mass per day They reproduce After 1 to 2 years they die

Life cycle of a cephalopod

Semelparous reproduction Iteroparity Sexual reproduction

Reproduction in cephalopods

Two part beak or radula Symbiotic digestive juices Digestive gland: crop, stomach, caecum and intestine Radulae description

Feeding of cephalopods

Pericardial cavity filters waste Delivered to renal sac Inflation and deflation of branchial hearts Release through pore

Excretory system of cephalopods

Exchange of gasses with seawater Water enters the cavity outside the gills Contraction of the water Jet propulsion Deplasation depends on respiraton

Respiratory system of cephalopods

Only molluscs with closed circulatory system Two gill hearts A single systematic heart Use of hemocyanin

Circulatory system of cephallopods

Most intelligent invertebrates Brain to body mass ratio Cartilageous cranium Nerve fibers use Highly adaptable

Nervous system of cephalopods

Advanced vision (color blind) Smell Tentacles use Hearing Use of light (coloration) Ink to confuse predators

Sensory system

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Any questions????