Download Chapter 29 / Coelomate Protostomes

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Chapter 29 / Protostomes
I. Introduction to the Protostomes
A. True Coelom (Appeared in Protostomes)
1. Body cavity—tube within a tube
a. mesoderm-lined
b. complete digestive tract
c. other well-developed systems
2. Advantages
a. separates muscle
b. aid in support
c. aid in transport of substances
d. space to contain and cushion organs
B. Adaptations for Terrestrial Life
1. First terrestrial animals were (invertebrate) coelomates
2. Problems of terrestrial living
a. dessication
b. reproduction
c. support
C. Two Major Protostome Branches
1. Lophotrochozoa
include: nemerteans, mollusks, annelids,
lophophores (bryozoans, phoronids, brachipods)
2. Ecdysozoa
include: rotifers, nematodes, arthropods
II. Phylum Nemertea—proboscis worms
free-living, marine
separate digestive and circulatory system
tube-within-a-tube body plan
one-way digestive tract; proboscis
III. Phylum Mollusca
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representatives: snail, squid, clam
A. Characteristics
1. visceral mass
2. foot
3. mantle
4. radula
5. more complex organ systems:
digestive tract, coiled within visceral mass
circulatory (open)
reproductive
excretory
nervous
B. Class Polytplacophora
Chitons ("many plates")
habitat: rocky intertidal zones
can use foot to form “suction cup”
C. Class Gastropoda
snails, slugs, nudibranchs, abalones, limpets
1. largest class of mollusks
2. cephalized foot
3. respiration: aquatic species have gills; terrestrial species lack gills
D. Class Bivalvia
clams, oysters, mussels, scallops
1. shells made of 2 halves
2. no distinct head
3. respiration and digestion (filtration)
4. move via foot
5. reproduction: larvae develop on gills of female
E. Class Cephalopoda
squids, octopi, nautiluses
1. most active mollusks
2. highly cephalized head
3. closed circulatory system
4. other characteristices:
squid and octopus have strong beak
nautiluses only one in class with shell
squid and nautilus: move by "jet propulsion"
IV. Other Coelomate Phyla
Lophophorate Phyla:
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Characterized by the
lophophore, a ciliated
ring of tentacles surrounding
the mouth. Includes:
A. Phylum Brachiopoda—lamp shells
B. Phylum Bryozoa—moss animals
V. Phylum Annelida
segmented worms
A. Characteristics
1. segmentation
2. improved locomotion
B. Class Oligochaeta
“few bristles”
1. setae
2. d.t. with specialized regions
3. closed circulatory system
4. respiration through moist skin
5. cerebral ganglia and ventral nerve
6. waste removal—metanephridia
7. reproduction: hermaphroditic but cross fertilize
C. Class Polychaeta
"many bristles"
1. parapodia
2. head may have eyes and antennae
D. Class Hirudinea
leeches
1. no appendages or setae
2. external segmentation but lack internal septa found in oligochaetes and polychaetes
2. carnivores or blood-sucking parasites
parasites: anterior and posterior suckers
release antisthetic and hirudin
VI. Phylum Rotifera—rotifers
aquatic, microscopic
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“wheel animals”
Level of organization: three tissue layers and organ systems
Symmetry: bilateral; cephalization
Digestion: complete, one-way digestive tract; cilia, mastax,
intestine
Circulation and Gas exchange: diffusion
Waste disposal: flame cells and bladder
Nervous system: simple; brain, sense organs
Reproduction: sexual—parthenogenesis common
VII. Phylum Nematoda—roundworms
species vary in length
pseudocoelom; cuticle
many are parasitic
Level of organization: three tissue layers and organ systems
Symmetry: bilateral, cephalization
Digestion: one-way digestive tract
Circulation and Gas exchange: diffusion
Waste disposal: excretory canals
Nervous system: simple; “brain” (ganglia), 2 nerve cords,
sense organs
Reproduction: sexual—separate sexes
Trichinella, pork roundworm
1st host consumes (eggs)
↓
salivary and gastric glands,
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larvae develop in intestine→organs or muscle
↓
nd
2 host consumes
↓
intestines (larvae→adults)
↓
new larvae intestine→organs or muscle
VIII. Phylum Onychophora
velvet worms
non-segmented with fleshy appendages; inhabit tropical rain forests
Annelid-like features: internal segmentation
Arthropod-like features: “jaws” from appendages; open circulatory system
May have evolved from the Arthropod lineage.
IX. Phylum Arthropoda
A. Characteristics
1. paired, jointed appendages
2. 3 body regions
3. exoskeleton
4. open circulatory system
B. Subphylum Chelicerata
body plan—cephalothroax and abdomen
chelicerae, pedipalps, and 4 pairs walking legs
1. Class Merostomata—horseshoe crabs
2. Class Arachnida—spiders, mites, ticks, scorpions
book lungs
silk glands
chelicerae may deliver venom
C. Subphylum Crustacea
Characteristics:
some microsopic, some quite large
mandibles and biramous appendages
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appendages on thorax and abdomen
2 prs. Antennae
1. Order Decapoda
lobsters, crayfish, crabs, shrimp
carapace
chelipeds
swimmerets, uropods
2. Order Isopoda
marine; also includes terrestrial sow bugs and pill bugs
3. Order Copepoda
small, shrimplike; make up krill
D. Subphylum Uniramia
Characteristics:
uniramous appendages
1 pr. Antennae
1. Class Insecta
a. some major orders:
1) Diptera—flies, mosquitoes
2) Hemiptera—true bugs
3) Coleoptera—beetles, weevils
4) Hymenoptera—ants, bees, wasps
5) Lepidoptera—butterflies, moths
6) Odonata—damselflies, dragonflies
7) Homoptera—cicadas
8) Orthoptera—grasshoppers, mantids
b. characteristics/adaptations:
mainly terrestrial; most fly
greatest in diversity and numbers
three pairs of legs
tracheal tubes
Malpighian tubules
metamorphosis
c. economic importance:
pollination
food chain
pests
products
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disease vectors
2. Class Chilopoda
centipedes
carnivorous, poisonous claws
3. Class Diplopoda
millipedes
herbivorous
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