Invertebrates

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Invertebrates

• Chapter 33

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Animal Origins
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Animal Origins
Animalia
Choanoflagellates
Diplomonadida
Parabasala
Euglenozoa
Chlorophyta
Rhodophyta
Cercozoa
Radiolaria
Plantae
Fungi
Alveolata
Stramenopila
Amoebozoa
Ancestral eukaryote
Figure 28.4
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Characteristics of the Animal Kingdom
None of the following are unique to animals, but
together distinguish animals from other
organisms
Multicellular
Heterotrophic
No cell walls
Motile during some stage(s) in life
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Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
Organized federation of cells vs. cells in tissues
Tissue integrated group of cells with a common
structure and function
Tissues are generally further integrated into
organs
Organs are generally further integrated into
organ systems
6
Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
For organisms with tissues two vs. three
principal embryonic tissues
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Characteristics of the Animal Kingdom
Two embryonic tissue layers
Blastocoel
Zygote
Blastula
Blastocoel
Endoderm
Ectoderm
Gastrulation
Archenteron
Gastrula
Blastopore
Fig. 32.2
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Characteristics of the Animal Kingdom
Two embryonic tissue layers
Endoderm Innermost germ layer differentiates
into some of the internal tissues and the lining
of most hollow organs, if these are
present Ectoderm Outermost germ layer
differentiates into tissues that cover the body
and into the nervous tissues
Blastocoel
Endoderm
Ectoderm
Archenteron
Gastrula
Blastopore
Fig. 32.2
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Characteristics of the Animal Kingdom
Three embryonic tissue layers
Fig. 32.9
Endoderm Innermost germ layer differentiates
into some of the internal tissues and the lining
of most hollow organs, if these are
present Mesoderm Middle germ layer
differentiates into muscles, circulatory and
skeletal systems, and sex organs, if these are
present Ectoderm Outermost germ layer
differentiates into tissues that cover the body
and into the nerve tissues
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Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
Radial vs. bilateral symmetry
Fig. 32.7
A single midline plane produces roughly
mirror-image halves generally accompanied by
distinct cephalization
Any plane that passes through the central axis
produces roughly mirror-image halves
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Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
Among organisms with 3 germ layersAcoelomate,
pseudocoelomate, or coelomate
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Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
Among organisms with 3 germ layersAcoelomate,
pseudocoelomate, or coelomate
Fig. 32.8
Acoelomate lack a coelom, i.e., lack a body
cavity between digestive track and body wall
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Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
Among organisms with 3 germ layersAcoelomate,
pseudocoelomate, or coelomate
Fig. 32.8
Pseudocoelomate Fluid-filled body cavity between
digestive tract and body wall partially lined by
mesoderm
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Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
Among organisms with 3 germ layersAcoelomate,
pseudocoelomate, or coelomate
Fig. 32.8
Coelomate fluid-filled body cavity between
digestive tract and body wall completely lined by
mesoderm
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Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
Protostome vs. deuterostome development
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Characteristics of the Animal Kingdom
A great diversity of body plans occur some key
features include
Protostome vs. deuterostome development
See Fig. 32.9
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The Animal Kingdom
35 phyla
Fig. 32.11Table 33.7
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Phylum Porifera Sponges
Figure 33.2
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Phylum Porifera Sponges
Organized aggregation of cells
Probably the most similar extant group to the
protistan colonial precursors to the animals
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Phylum Porifera Sponges
Organized aggregation of cells
Three main cell types, but no true tissues
Asymmetric body plan
Mostly marine, but some inhabit fresh water
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Phylum Porifera Sponges
Internal skeleton of protein spicules
E.g., natural bath sponge
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Eumetazoa
All animals except sponges belong to the clade
Eumetazoa
All eumetazoans have true tissues
Figure 33.2
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Phylum Cnidaria Corals, Jellyfish, Anemones
Radially symmetric animals with 2 germ layers
(true tissues), but generally lacking true
organs
Rudimentary nerve net and contractile tissue
Gastrovascular cavity mouth and anus are the
same opening
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Phylum Cnidaria Corals, Jellyfish, Anemones
Tentacles contain cnidocytes
Fig. 33.6
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Phylum Cnidaria Corals, Jellyfish, Anemones
Polyp and medusa forms
Fig. 33.5
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Phylum Cnidaria Corals, Jellyfish, Anemones
Polyp and medusa forms
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Phylum Ctenophora Comb jellies
8 rows of comblike plates of cilia
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Bilateria
Bilaterally symmetric, cephalized animals with 3
germ layers
Figure 33.2
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P. Platyhelminthes Flat worms
Gastrovascular cavity (if a gut is present)
Some true organs are present (tissues grouped
into functional structures)
Hermaphroditic and capable of self-fertilization
Acoelomate
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P. Platyhelminthes Flat worms
Mostly free-living
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P. Platyhelminthes Flat worms
Mostly free-living
Some parasitic
E.g., tapeworms
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P. Rotifera Rotifers
Distinguishing feature is a crown of cilia
around the mouth
Complete digestive tract surrounded by
pseudocoelom
Parthenogenesis (development from unfertilized
eggs) is the most common mode of reproduction
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P. EctoproctaP. PhoronidaP. Brachiopoda
All bear a lophophore fold of the body wall
bearing ciliated tentacles surrounding the mouth
Coelomate
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P. Ectoprocta
a.k.a. bryozoans
Colonial
Many contribute to marine reefs
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P. Phoronida
A group of tube-dwelling marine worms
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P. Brachiopoda
a.k.a. lamp shells
Marine, mostly extinct
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P. Nemertea
a.k.a. proboscis or ribbon worms
Structurally acoelomate, with a small
fluid-filled sac that may be a vestigial coelom
Closed circulatory system, but no heart
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P. Mollusca
a.k.a. mollusks
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P. Mollusca
a.k.a. mollusks
Coelomate body with a muscular foot, visceral
mass, and mantle (which secretes a shell in many
species)
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P. Mollusca
a.k.a. mollusks
8 classes, including C. Polyplacophora (chitons)
Shell divided into 8 plates
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P. Mollusca
a.k.a. mollusks
8 classes, including C. Gastropoda (snails and
slugs)
Single shell or lacking shell
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P. Mollusca
a.k.a. mollusks
8 classes, including C. Gastropoda (snails and
slugs)
Single shell or lacking shell
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P. Mollusca
a.k.a. mollusks
8 classes, including C. Bivalvia (clams,
oysters, mussels, etc.)
Hinged, two-part shell
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P. Mollusca
a.k.a. mollusks
8 classes, including C. Cephalopoda (squids,
octopuses, nautiluses)
Only mollusks with closed circ. system and
complex brain
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P. Mollusca
a.k.a. mollusks
8 classes, including C. Cephalopoda (squids,
octopuses, nautiluses)
Only mollusks with closed circ. system and
complex brain
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P. Annelida
a.k.a. segmented worms
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P. Annelida
a.k.a. segmented worms
Segmented
Coelomate
Coelom
Closed circulatory system
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P. Annelida
a.k.a. segmented worms
3 classes C. Oligochaeta Earthworms and their
kin
Coelom
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P. Annelida
a.k.a. segmented worms
3 classes C. Polychaeta Bristled parapodia on
each segment
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P. Annelida
a.k.a. segmented worms
3 classes C. Hirudinea Leeches
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P. Nematomorpha
Not required to know
a.k.a. horsehair or gordian worms
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P. Priapulida
Not required to know
a.k.a. penis worms
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P. Tardigrada
Not required to know
a.k.a. water bears
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P. Onychophora
Not required to know
a.k.a. velvet worms
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P. Nematoda
a.k.a. roundworms
Nonsegmented
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P. Nematoda
a.k.a. roundworms
Nonsegmented
No circulatory or respiratory systems
Anus
Gut
Mouth
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P. Nematoda
a.k.a. roundworms
Nonsegmented
No circulatory or respiratory systems
Pseudocoelomate
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P. Nematoda
a.k.a. roundworms
Nonsegmented
No circulatory or respiratory systems
Pseudocoelomate
Free living or parasitic
E.g., dog heartworm
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P. Arthropoda
Segmented
Coelomate
Exoskeleton of chitin
Jointed appendages
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P. Arthropoda
Open circulatory system
Hemolymph (the open-circulation system equivalent
of blood) carries dissolved gases through short
vessels and the hemocoel (main body cavity in
adults, since coelom is reduced)
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P. Arthropoda
As in much of modern systematics, classes are in
flux nevertheless, here are 5 main groups
Trilobites all extinct during Permain mass
extinction 250 mya
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P. Arthropoda
Cheliceriforms horseshoe crabs
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P. Arthropoda
Cheliceriforms sea spiders
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P. Arthropoda
Cheliceriforms Arachnids spiders, ticks,
scorpions, mites
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P. Arthropoda
Cheliceriforms Arachnids spiders, ticks,
scorpions, mites
mite
spider (tarantula)
tick
scorpion
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P. Arthropoda
Cheliceriforms Arachnids spiders, ticks,
scorpions, mites
Adults generally have 4 pairs of walking legs
Some produce silk
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P. Arthropoda
Cheliceriforms Arachnids spiders, ticks,
scorpions, mites
Eyes of black widow spider
Simple eyes (each with a single lens)
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P. Arthropoda
Myriapods millipedes 2 pairs of legs per
segment
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P. Arthropoda
Myriapods centipedes 1 pair of legs per segment
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P. Arthropoda
Hexapods insects
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P. Arthropoda
Hexapods insects
Adult often has 2 pairs of wings
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P. Arthropoda
Hexapods insects
Sometimes 1 pair of wings sometimes none
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P. Arthropoda
Hexapods insects
Adult generally has 3 pairs of legs
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P. Arthropoda
Hexapods insects
Metamorphosis transition between distinct
(often dramatically different) developmental
stages
Larva (maggot, caterpillar)
Pupa (transition to adult)
Adult (often winged)
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P. Arthropoda
Hexapods insects
Metamorphosis transition between distinct
(often dramatically different) developmental
stages
Larva (maggot, caterpillar)
Pupa (transition to adult)
Adult (often winged)
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P. Arthropoda
Hexapods insects
Adult generally has compound eyes
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See also Fig. 33.37
Insects Some of the major orders (26 in
total) Order Coleoptera Beetles Order
Hemiptera True Bugs Order Homoptera Aphids
and their kin Order Hymenoptera Ants, Bees,
Wasps Order Isoptera Termites Order
Lepidoptera Butterflies and Moths Order
Odonata Dragonflies and Damselflies Order
Orthoptera Crickets, Grasshoppers, Katydids O
rder Siphonaptera Fleas
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P. Arthropoda
As in all arthropods, crustaceans have segmented
body plans
Crustaceans
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P. Arthropoda
Crustaceans
waterflea
sowbug
hermit crab
barnacle
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P. Arthropoda
Often have 5 or more pairs of legs
Crustaceans
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P. Arthropoda
Generally have compound eyes
Crustaceans
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Deuterostomia
Deuterostome developmental pathway
Coelomates
Figure 33.2
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P. Echinodermata
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P. Echinodermata
At first glance they may seem more radially than
bilaterally symmetrical
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P. Echinodermata
However, their larvae are obviously bilaterally
symmetrical
Sea star adult
Sea star larva
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P. Echinodermata
Brittle star
Sand dollar
Sea cucumber
Sea urchin
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P. Echinodermata
Calcium carbonate endoskeleton
Brittle star
Sand dollar
Sea cucumber
Sea urchin
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P. Echinodermata
Unique water vascular system of hydraulic canals
branching into tube feet for locomotion, feeding,
and gas exchange
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P. Chordata
At some stage in development, all chordates
possess