Mollusks General Characteristics Kingdom Animalia Phylum Mollusca soft

General Characteristics • Kingdom: Animalia • Phylum: Mollusca “soft body” • Class: Cephalopoda “head-footed”

Groups of Mollusks • Classified according to their foot and shell • Three major

Characteristics • • • 112, 000 species Coelomates Soft body with internal or external

7 survival systems • Feeding & Digestion ▫ mouth, anus and complex stomach ▫

• Circulatory ▫ Open circulatory system- gastropoda & bivalvia ▫ Closed circulatory system-

• Reproduction ▫ Internal fertilization (cephalopods) ▫ External fertilization • Movement ▫ Varies

Gastropods • • snails, slugs, limpets and nudibranchs Shell-less or single shelled Move by

Cephalopoda • • • octopi, squids, and cuttlefish soft-bodied , head is attached to

General Characteristics • Invertebrates • No cephalization (no head region) • Deuterostomes- recall from

Unique Characteristics • Endoskeleton ▫ Made up of plates called ossicles • Water-vascular system

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Mollusks

General Characteristics • Kingdom: Animalia • Phylum: Mollusca “soft body” • Class: Cephalopoda “head-footed” (squid) • Examples of Mollusca ▫ ▫ Clams Snails Slugs Octopuses

Groups of Mollusks • Classified according to their foot and shell • Three major classes of mollusks �Gastropods �Bivalves �Cephalopods

Characteristics • • • 112, 000 species Coelomates Soft body with internal or external shell Larval stage called a trochophore Body plan: ▫ ▫ Foot – takes on many forms Mantle – covers the body Shell – (present in most) Visceral mass – internal organs

7 survival systems • Feeding & Digestion ▫ mouth, anus and complex stomach ▫ radula-help the mollusks scrape algae and force food backward ▫ Some filter feed-through their gills ▫ Tentacles- grab and hold prey • Excretion ▫ carried out by a pair of nephridia (earthworm also had this) ▫ Empties into the mantle cavity

• Circulatory ▫ Open circulatory system- gastropoda & bivalvia ▫ Closed circulatory system- cephalopoda • Respiration ▫ Use gills to exchange O 2 and CO 2 • Response ▫ ▫ Mental capacity like that of a cat Largest eyes among animals Complex nervous system Nerve ring located around the mouth with a nerve cord connected to ganglia

• Reproduction ▫ Internal fertilization (cephalopods) ▫ External fertilization • Movement ▫ Varies among classes of mollusks �Gastropoda- crawling �Bivalvia- sessile �Cephalopoda- rapid swimming

Gastropods • • snails, slugs, limpets and nudibranchs Shell-less or single shelled Move by a muscular foot Some are poisonous, bright colors

Bivalves • Things with two shells

Cephalopoda • • • octopi, squids, and cuttlefish soft-bodied , head is attached to foot is divided into tentacles with sucking disks small internal shells or no shell at all Squid have a modified shell called a pen most complex of the mollusks

Echinoderms “spiny skin”

General Characteristics • Invertebrates • No cephalization (no head region) • Deuterostomes- recall from earlier what this means? • Habitat- marine environments • Examples: ▫ ▫ Sea stars Sand dollars Sea urchins Sea cucumbers

Unique Characteristics • Endoskeleton ▫ Made up of plates called ossicles • Water-vascular system • Tube feet ▫ Extensions that aid in movement, feeding, respiration and excretion