1. Mollusca, Annelida, Arthropoda
The Protostomes
Mollusca, Annelida, Arthropoda

2. Parazoa no true tissues
Radiata
Bilateria
Eumetazoa
Parazoa no true tissues
Multicellularity

3. Protostomes “mouth first”
Deuterostomes “mouth second”

4. type of digestive system
Common Features
Features
Mollusca
Annelida
Arthropoda
# of germ layers
triploblasts
type of symmetry
bilaterally-symmetric
body cavity
coelom present
fate of blastopore
mouth develops first
type of digestive system
complete digestive system

5. Distinguishing features
Mollusca
Annelida
Arthropoda
Etymology
molluscus, “soft”
annellus
“little ring”
arthron + podos
“joint foot”
General description
soft-bodied animals with an external or internal shell
soft, segmented worms
segmented body, tough exoskeleton, jointed appendages
# of species
~100,000 spp.
~15,000 sp.
~750,000 sp. (highest sp. diversity)

6. Mollusk Body plan muscular foot mantle calcium carbonate shell
visceral mass ,

7. Annelid body plan metameres or segments septa setae or chaetae
sense organs

8. Arthropod body plan body segments exoskeleton of protein + chitin
appendages that extend from the body wall

9. aquatic: gills inside mantle cavity
Phylum
Mollusca (L. molluscus, “soft”)
Feeding
herbivores, carnivores, filter feeders, detritivores, parasites
filter feeders: incurrent/excurrent siphon, mucus & cilia on gills
radula
Respiration
aquatic: gills inside mantle cavity
terrestrial: constantly moist & highly vascularized mantle cavity
Circulation
open circulatory system (snails, clams): sinus
closed circulatory system (squid, octopuses)
Excretion
nephridia
Response
simple nervous system (bivalves)
highly-developed nervous system (squid, octopuses)
Movement
foot + mucus (snails)
jet propulsion (octopuses)
Reproduction
external fertilization (snails, bivalves)
internal fertilization (cephalopods, some snails)
hermaphroditic, cross-fertilization
trochophore larvae

10. Phylum Mollusca Gastropoda snails and slugs Cephalopoda
octopuses,squids, cuttlefish, Nautilus
Bivalvia
clams, oysters, mussels, scallops
Scaphopoda
tusk shells
Aplacophora, Monoplacophora, Polyplacophora
chiton

11. radula in gastropods jaws in cephalopods Feeding
herbivores, carnivores, filter feeders, detritivores, parasites
filter feeders: incurrent/excurrent siphon, mucus & cilia on gills in bivalves
radula in gastropods
jaws in cephalopods

12. aquatic: gills inside mantle cavity
Respiration
aquatic: gills inside mantle cavity
terrestrial: constantly moist & highly vascularized lung in mantle cavity

13. open circulatory system (snails, clams): sinus
Circulation
open circulatory system (snails, clams): sinus
closed circulatory system (squid, octopuses)

14. Excretion
nephridia

15. simple nervous system (bivalves)
Response
simple nervous system (bivalves)
highly-developed nervous system (squid, octopuses)

16. jet propulsion (octopuses)
Movement
foot + mucus (snails)
jet propulsion (octopuses)

17. external fertilization (snails, bivalves)
Reproduction
external fertilization (snails, bivalves)
internal fertilization (cephalopods, some snails)
hermaphroditic, cross-fertilization
trochophore larvae

19. herbivores, carnivores, detritivores pharynx
Phylum
Annelida (L. annellus, “ring”)
Feeding
herbivores, carnivores, detritivores
pharynx
Respiration
aquatic: through gills in their chaetae
terrestrial: diffusion through moist skin
Circulation
closed circulatory system (blood vessels and multiple hearts)
Excretion
nephridia in each segment
Response
highly-developed nervous system
Movement
terrestrial: contraction of longitudinal and circular muscles against the hydrostatic skeleton
aquatic: paddling of the parapodia
Reproduction
asexual: fragmentation, budding in aquatic forms
some hermaphroditic, cross-fertilization
internal fertilization in most
trochophore larvae in marine forms
eggs in cocoons in terrestrial forms

20. aquatic: through gills in their chaetae
Respiration
aquatic: through gills in their chaetae
terrestrial: diffusion through moist skin

21. closed circulatory system (blood vessels and multiple hearts)
Circulation
closed circulatory system (blood vessels and multiple hearts)

22. asexual: fragmentation, budding in aquatic forms
Reproduction
asexual: fragmentation, budding in aquatic forms
some hermaphroditic, cross-fertilization
internal fertilization in most
trochophore larvae in marine forms
eggs in cocoons in terrestrial forms

23. bristle worms, sandworm, clamworm
Phylum Annelida
Oligochaeta
earthworms, Tubifex
Polychaeta
bristle worms, sandworm, clamworm
Hirudinea
leeches

24. fangs, proboscis, sickle-shaped jaws, pincers
Phylum
Arthropoda (G. arthron + podos, “joint foot”)
Feeding
herbivores, carnivores, omnivores, bloodsuckers, filter feeders, detritivores, parasites
fangs, proboscis, sickle-shaped jaws, pincers
Respiration
terrestrial: spiracles and tracheal tubes or book lungs in spiders
aquatic: feather-like gills in lobsters, crabs and book gills in horseshoe crabs
Circulation
open circulatory system (heart  blood vessels  sinuses  heart)
Excretion
aquatic: diffusion
terrestrial: Malpighian tubules
Response
highly-developed nervous system with brain, nerve cords, ganglia, and sense organs
Movement
well-developed muscle groups
exoskeleton
Reproduction
aquatic: internal/external fertilization
terrestrial: internal fertilization
metamorphosis: complete/incomplete

25. Phylum Arthropoda Crustaceans
crabs, crayfish, lobsters, barnacles, shrimps
Chelicerates
horseshoe crab, ticks, spiders, mites, scorpions
Uniramia
centipedes, millipedes, insects
Trilobita
trilobites (extinct)

26. fangs, proboscis, sickle-shaped jaws, pincers
Feeding
herbivores, carnivores, omnivores, bloodsuckers, filter feeders, detritivores, parasites
fangs, proboscis, sickle-shaped jaws, pincers

27. terrestrial: spiracles and tracheal tubes or book lungs in spiders
Respiration
terrestrial: spiracles and tracheal tubes or book lungs in spiders
aquatic: feather-like gills in lobsters, crabs and book gills in horseshoe crabs

28. open circulatory system (heart  blood vessels  sinuses  heart)
Circulation
open circulatory system (heart  blood vessels  sinuses  heart)

29. terrestrial: Malpighian tubules
Excretion
aquatic: diffusion
terrestrial: Malpighian tubules

30. Response
highly-developed nervous system with brain, nerve cords, ganglia, and sense organs