BIOL 112 Lecture Notes - Lecture 2: Vas Deferens, Seminal Vesicle, Ventral Nerve Cord
11 Jan 2017
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10/23/16
Lab 8 Review: Invertebrate Diversity II-Lophotrochozoans
Practical
• Esp. know things that were dissected, subphylum and class names, things in jars/containers
• General diagrams about coelom types, symmetry, protostome vs. deuterostome (pg. 155)**
• Pg. 173 diagram!
• 104 point exam; 1 bonus station!
• **Cross-sections station: Ascaris male/female, fluke, earthworm, sea lancelet
• shells station: mollusk (clam) vs. brachiopods-has opening for pedicle?
Exercise 8
• Sponges: NO true tissues; basal animal
• Cnidarians: diploblastic-ecto and endoderm
• Worms: triploblastic-mesoderm
o Embryonic mesoderm→muscles, bones, etc.
• Coelom: body cavity completely lined w/embryonic mesodermal tissue
o Evo. advantage: defined cavities and connective tissue
o True coelom: protostomes (schizocoelus-split) and deuterostomes (enterocoelus)
o Compartmentalizes body cavities/organ systems and creates connective tissue to keep organ
tissues in place
• Protostomes:
o Blastopore’s fate→mouth; 2nd opening becomes anus
o Schizocoelus=”splitting event”
o Spiral cell cleavage: daughter cell is off-center from parent cell
o Determinate cell fate: every cell in embryo determines body part
• Deuterostomes
• Lophotrochozoans-triploblastic; do NOT molt
o Lophophore and trochophore (larval stage)=closely related evo.
▪ There are animals in this clade that don’t have either!!**
o Phylum Platyhelminthes: Flatworms: acoelomates; NOT proto/deuterostome, bilateral symmetry ;
free living and parasitic; all=hermaphroditic (have both male and female structures)
▪ Rhabditophorans
• Planarians: free-living; looks like fluke w/eyespot-most primitive EM detectors;
acoelomate; ocelli (negative phototaxis); protonephridia (flame cells) for
osmoregulation; every cell close to digestive tract bc no cardio. system
o Anatomy: head, auricles, ocelli, ganglion, nerve cords, pharynx,
diverticula/ceca
• Trematodes-parasitic (flukes)
o Complex life cycle requiring > 1 host
o Anatomy: oral sucker, mouth, bile duct, ventral sucker, pharynx,
esophagus, intestinal sacs
o Male structure=2 testes, vas deferens, uterus, seminal vesicle, genital
pore
o Female structure=seminal receptacle, oviduct, ovary, yolk glands, yolk
ducts, uterus, eggs, genital pore
• Tapeworms: parasitic
o Anatomy: scolex, rostellum, suckers, proglottid (repro. system)
o Use digestive system of host
o Self-fertilization??
o Phylum Brachiopoda (Lophophorates): sessile, true coelom, lophophore (filter feeding); very
abundant in fossil record; shells w/2 opposing valves enclosing soft body; pedicle
▪ Anatomy: 2 unequal valves, mantle, lophophore, digestive tract, pedicle-anchorage,
adductor muscle,, nephridia (analogous to kidneys), mesosome and metasome
▪ Articulate (Lamp Shells); most common brachiopods
• Articulating valves hinged along posterior edge
o Teeth-open valves for feeding
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