Protostomes

1
Protostomes

• Phylum Mollusca
• Phylum Annelida
• Phylum Arthropoda

2
Protostomes

• Three major phyla share two embryonic characters
• Mouth develops at site of blastopore (1st mouth)
• Mesoderm develops from lips of blastopore as
  solid masses, splits
• split coelom

3
Protostomes

• Formation of Mesoderm and Coelom
• Solid masses of mesoderm separate from lips of
  blastopore.
• Split opens in mesoderm to form split coelom

4
Phylum Mollusca

• Phylum Mollusca (Greek soft)
• 100,000 species, 2nd largest phylum
• Body plan
• Tube-in-tube, Protostomous
• Bilateral symmetry
• Coelomate, split coelom
• Marine, aquatic, terrestrial

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Phylum Mollusca

• Body with three parts
• Visceral mass (torso)
• Mouth, gut, heart, gill, reproductive organs
• Mantle
• Sheet of tissue attached to middle of back
• Mantle cavity space between mantle visceral
  mass
• Foot
• Single muscular sheet contacts substrate
• Creeps with 100s of little muscles

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Phylum Mollusca

• Visceral mass (torso)
• Mantle
• Mantle cavity space between mantle visceral
  mass
• Foot

7
Phylum Mollusca

• Unique, distinguishing characters
• Mantle,
• foot,
• Radula
• Tooth-bearing scraping jaw

8
Animal Life

• F. Ways the needs of cells are met
• 1. Food
• 2. O2 and CO2 exchange
• 3. Waste removal

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Phylum Mollusca

• Style in stomach
• Hard crystalline rod of digestive enzymes
• Spins in stomach, wraps string of mucus and food
• Ground away at posterior end along with mucus and
  food

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Animal Life

• G. Special concerns of a multicellular animal
• Circulation, Coordination, Structural support,
  Movement, Maintenance of homeostasiswater
  balance.
• Reproduction
• Usually sexual, sexes usually separate

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Phylum Mollusca

• Coelom reduced to pericardial cavity
• Open Circulatory System
• No blood vessels (almost)
• Blood pumped forward through head, then oozes
  through visceral mass, around organs, muscles,
  gills, back to heart
• Hemocoel

12
Phylum Mollusca

• Nervous system
• Brain small, surrounds esophagus
• Pair of visceral nerve cords
• Pair of pedal nerve cords

13
Phylum Mollusca

• Class Chitons
• chitons
• Class Gastropods
• snails, slugs, nudibranchs
• Class Bivalves
• clams, mussels, oysters, etc.
• Class Cephalopods
• squids, Octopus, cuttlefish, Nautilus

14
Phylum Mollusca

• Class Chitons
• Chitons
• Thick mantle with eight shell plates
• Scrape algae, etc. from rocks

15
Phylum Mollusca

• Class Gastropods
• snails, slugs, nudibranchs
• Torsion
• Bending twisting of gut
• Conical, spiral shell

16
Phylum Mollusca

• Class Gastropods

17
Phylum Mollusca

• Class Bivalves
• clams, mussels, oysters, etc.
• Filter feeders
• Gill used as filter
• Radula usually lost
• Shells on left, right

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Phylum Mollusca

• Class Cephalopods
• squids, Octopus, Nautilus, cuttlefish,
• Siphon on mantle edge
• rocket away from predators
• Tentacles with suction cups

19
Phylum Mollusca

• Class Cephalopods
• Octopus
• Complex behavior, learning