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THE PROTOSTOMES
M O L L U S C A , A N N E L I D A , A RT H R O P O D A
Radiata
Parazoa
no true tissues
Bilateria
Eumetazoa
Multicellularity
PROTOSTOMES
“mouth first”
DEUTEROSTOMES
“mouth second”
COMMON FEATURES
Features
# of germ
layers
type of
symmetry
body cavity
fate of
blastopore
type of
digestive
system
Mollusca
Annelida
Arthropoda
triploblasts
bilaterally-symmetric
coelom present
mouth develops first
complete digestive system
DISTINGUISHING FEATURES
Features
Mollusca
Annelida
Arthropoda
Etymology
molluscus, “soft”
annellus
“little ring”
arthron + podos
“joint foot”
soft-bodied
General
animals with an soft, segmented
external or
worms
description
internal shell
# of species
~100,000 spp.
~15,000 sp.
segmented
body, tough
exoskeleton,
jointed
appendages
~750,000 sp.
(highest sp.
diversity)
MOLLUSK BODY
PLAN
•
•
•
•
muscular foot
mantle
calcium carbonate shell
visceral mass
http://www.bio.miami.edu/dana/pix/ham.jpg, http://kentsimmons.uwinnipeg.ca/16cm05/1116/33-21-ClamAnatomy-L.jpg, ,
http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T010708A.gif
ANNELID BODY PLAN
• metameres
or segments
• septa
• setae or
chaetae
• sense
organs
ARTHROPOD
BODY PLAN
• body segments
• exoskeleton of
protein + chitin
• appendages that
extend from the
body wall
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
Excretion
Response
Movement
Reproduction
• open circulatory system (snails, clams): sinus
• closed circulatory system (squid, octopuses)
• nephridia
•
•
•
•
simple nervous system (bivalves)
highly-developed nervous system (squid, octopuses)
foot + mucus (snails)
jet propulsion (octopuses)
•
•
•
•
external fertilization (snails, bivalves)
internal fertilization (cephalopods, some snails)
hermaphroditic, cross-fertilization
trochophore larvae
Phylum Mollusca
Gastropoda
snails and slugs
Cephalopoda
octopuses,squids,
cuttlefish, Nautilus
Bivalvia
clams, oysters, mussels,
scallops
Scaphopoda
tusk shells
Aplacophora,
Monoplacophora,
Polyplacophora
chiton
Feeding
• herbivores, carnivores, filter feeders, detritivores, parasites
• filter feeders: incurrent/excurrent siphon, mucus & cilia on
gills in bivalves
• radula in gastropods
• jaws in cephalopods
Respiration
• aquatic: gills inside mantle cavity
• terrestrial: constantly moist & highly vascularized
lung in mantle cavity
Circulation
• open circulatory system (snails, clams): sinus
• closed circulatory system (squid, octopuses)
http://chsweb.lr.k12.nj.us/mstanley/outlines/circulation/Circulation_files/image013.gif
Excretion
• nephridia
Response
• simple nervous system (bivalves)
• highly-developed nervous system (squid,
octopuses)
http://classconnection.s3.amazonaws.com/754/flashcards/566754/png/49.21320629922544.png
Movement
• foot + mucus (snails)
• jet propulsion (octopuses)
Reproduction
•
•
•
•
external fertilization (snails, bivalves)
internal fertilization (cephalopods, some snails)
hermaphroditic, cross-fertilization
trochophore larvae
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
Respiration
• aquatic: through gills in their chaetae
• terrestrial: diffusion through moist skin
Circulation
• closed circulatory system (blood vessels and
multiple hearts)
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
Phylum Annelida
Oligochaeta
earthworms, Tubifex
Polychaeta
bristle worms,
sandworm, clamworm
Hirudinea
leeches
Phylum
Arthropoda (G. arthron + podos, “joint foot”)
Feeding
• herbivores, carnivores, omnivores, bloodsuckers, filter
feeders, detritivores, parasites
• fangs, proboscis, sickle-shaped jaws, pincers
• terrestrial: spiracles and tracheal tubes or book lungs in
spiders
• aquatic: feather-like gills in lobsters, crabs and book gills
in horseshoe crabs
Respiration
Circulation
Excretion
Response
Movement
Reproduction
• open circulatory system (heart  blood vessels 
sinuses  heart)
• aquatic: diffusion
• terrestrial: Malpighian tubules
• highly-developed nervous system with brain, nerve
cords, ganglia, and sense organs
• well-developed muscle groups
• exoskeleton
• aquatic: internal/external fertilization
Phylum Arthropoda
Crustaceans
crabs, crayfish, lobsters,
barnacles, shrimps
Chelicerates
horseshoe crab, ticks,
spiders, mites, scorpions
Uniramia
centipedes, millipedes,
insects
Trilobita
trilobites (extinct)
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