Phylum Mollusca Coelomates- have coelom More than 110,000 … · Mollusks Phylum Mollusca...
Transcript of Phylum Mollusca Coelomates- have coelom More than 110,000 … · Mollusks Phylum Mollusca...
Mollusks Phylum Mollusca
Coelomates- have coelom
More than 110,000 species
Survive on land, fresh and marine waters.
Body Structure Bilateral symmetry
Soft internal body
Digestive tract, respiratory system, circulatory system and nervous system.
Have a mantle; which is a membrane that surrounds the internal organs or mollusks. Mantle can secrete calcium carbonate to form a
shell.
Body structure
Feeding and digestion Can be herbivorous, carnivorous or filter
feeders.
Radula- tonguelike organ with rows of teeth.
Radula is used for scraping algae off rocks or to drill into other animals to feed on internal body parts.
Have two openings to digestive tract.
Have stomach and intestine
Respiration Most mollusks have gills
Gills- parts of the mantle that consist of a system of filamentous projections. used to transport oxygen into and to remove
carbon dioxide from the blood. Move water through the mantle
Increase surface area for gas diffusion
Land snails and slugs take in oxygen using mantle cavities.
Circulation Have a chambered heart
Most mollusks have a open circulatory system Blood is pumped to open spaces surrounding body
organs Utilized by slow moving animals (snails, slugs)
Some mollusks have closed circulatory system Blood is confined to vessels as it moves through body Used by animals that move quickly (squid and
octopus)
Excretion Most mollusks get rid of metabolic waste through
the nephridia.
Nephridia- maintains homeostasis in body fluids.
Response to stimuli Have nervous system that coordinates movement
and behavior.
Octopus have a brain and a complex eye.
Movement Muscular foot is used for movement
movement Squid and octopus use a siphon to move water into
and then expel it out of the mantle.
Reproduction Reproduce sexually
Most release eggs and sperm into water at the same time. (external fertilization)
Hermaphroditic mollusks use internal fertilization.
All mollusks have a larval stage called a trochophore.
Gastropods (Gastropoda) Stomach-footed mollusks
Most have single shell
Aquatic and moist terrestrial habitats
Can draw their bodies into their shell when threatened.
Slugs secrete mucus for protection
Nudibranchs incorporate jellyfish nematocysts into their bodies after eating them; for protection
Ex: snails, conches, periwinkles, limpets, cones.
Bivalves (Bivalvia) Two shelled mollusks
Most are marine Few found in freshwater
Continuously filter feeding
Ex: clams, mussels, oysters and scallops
Cephalopods (Cephalopoda) Head-footed mollusks
Foot is divided into arms and tentacles Have suckers; used to capture prey
Most can expel ink when threatened
Shells: Nautilus has external shell
Squid and cuttlefish have internal shell
Octopus has no shell
Octopuses, squid and cuttlefish can change color for camouflage
Nautilus can hide in its shell when threatened.