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Animals can be traced to a common
ancestor a flagellated protist like a
choanoflagellate (700 MYA)
Reproductive
cells
Somatic
cells
Digestive
cavity
1 Colonial protist,
an aggregate
of identical cells
2 Hollow sphere
of unspecialized
cells (shown in
cross section)
3 Beginning of cell
specialization
(cross section)
4 Infolding
(cross section)
5 Gastrula-like
“proto-animal”
(cross section)
The ancestor of animals was probably a colonial,
flagellated protist
– Cells in these protists
• Gradually became more specialized and layered
Figure 18.2A
Invertebrate: Porifera Sponges
– no distinct tissues or organs
• do have specialized cells
– no symmetry
– sessile (as adults)
food taken into each
cell by endocytosis
Sponges have a relatively simple, porous body
– Sponges, phylum Porifera
• Are the simplest animals and have no true tissues
INVERTEBRATES
Pores
Amoebocyte
Skeletal
fiber
Central
cavity
Choanocyte
in contact
with an
amoebocyte
Choanocyte
Water
flow
Flagella
– Flagellated choanocytes
• Filter food from the water passing through the porous
body
Invertebrate: Cnidaria Jellyfish, hydra, sea anemone, coral
– tissues, but no organs
– two cell layers
– radial symmetry
– predators
• tentacles surround
gut opening
• extracellular
digestion
– release enzymes
into gut cavity
hydra
stinging cell with nematocyst
trigger
discharged nematocyst
undischarged nematocyst
tentacles
mouth
sensory cell
stinging cell
Stinging cells of
Cnidarians
Cnidarians are radial animals with tentacles and
stinging cells
– Cnidarians, phylum Cnidaria
• Have true tissues and radial symmetry
– Their two body forms are
• Polyps, such as hydra
• Medusae, the jellies
Figure 18.6A–C
– They have a gastrovascular cavity
• And cnidocytes on tentacles that sting prey
Tentacle
“Trigger”
Coiled
thread
Capsule
(nematocyst)
Discharge
of thread
Cnidocyte Prey
Sea Nettle Portuguese man’o’ war
Sea wasp (box jelly)
Safe Comb Jellies
Invertebrate: Platyhelminthes
ectoderm
mesoderm
endoderm
Flatworms – tapeworm, planaria
– mostly parasitic
– bilaterally symmetrical
• allows high level of specialization
within parts of the body
• now have a mouth at one end
& an anus at the other!
Units with
reproductive
structures
Scolex
(anterior
end) Hooks
Sucker
Co
lori
zed
SE
M 8
0
Invertebrate: Nematoda
Roundworms
– bilaterally symmetrical
– have both mouth & anus
• well-developed digestive system
– many are parasitic
• hookworm
C. elegans
Ascaris
Invertebrate: Mollusca
Mollusks
– clams, snails, squid
– bilaterally symmetrical (with exceptions)
– soft bodies, mostly protected by hard shells
– true coelem
Gastropods
– Gastropods are the largest group of molluscs
• And include the snails and slugs
Bivalves
– The bivalves have shells divided into two halves
• And include clams, oysters, mussels, and scallops
Cephalopods
– Cephalopods are adapted to be agile predators
• And include squids and octopuses
Wiwaxia – between mollusca and annelida
Open Versus Closed
circulatory System
Open circulatory system – A heart pumps
hemolymph through a hollow cavity to circulate
O2 and nutrients.
Arthropods and some molluscs
Closed Circulatory System – a Heart pumps blood
through”closed” blood vessels and lymph is kept
separate.
Chordates, cephalopods and annelids
Invertebrate: Annelida – Segmented worms
• earthworms, leeches
• segments are not specialized
• bilaterally symmetrical
• true coelem
fan worm leech
Invertebrate: Arthropoda
Spiders, insects, crustaceans
– most successful animal phylum
– bilaterally symmetrical
– segmented
• allows jointed appendages
– exoskeleton
• chitin + protein
Arthropod groups
insects 6 legs, 3 body parts
crustaceans gills, 2 pairs antennae
crab, lobster, barnacles, shrmp
arachnids 8 legs, 2 body parts
spiders, ticks, scorpions
Chelicerates
– Chelicerates include
• Horseshoe crabs
• Arachnids, such as spiders, scorpions, mites, and ticks
A scorpion (about 8 cm long)
A black widow spider (about
1 cm wide)
A dust mite (about 420
µm long)
Colo
rize
d S
EM
90
0
Figure 18.11B, C
Millipedes and Centipedes
– Millipedes and centipedes
• Are identified by the number of jointed legs per body
segment
Crustaceans
– The crustaceans
• Are nearly all aquatic
• Include crabs, shrimps, and barnacles
Insects are the most diverse group of organisms
– Insects have a three-par t body consisting of
• Head, thorax, and abdomen
• Three sets of legs
• Wings (most, but not all insects)
– Many insects undergo
• Incomplete or complete metamorphosis
A. Order Or thoptera
– The order orthoptera includes
• Grasshoppers, crickets, katydids, and locusts
Head Thorax Abdomen
Antenna Forewing
Eye
Mouthparts Hindwing Figure 18.12A
B. Order Odonata
– The order odonata includes
• Dragonflies and damselflies
Figure 18.12B
C. Order Hemiptera
– The order hemiptera includes
• Bedbugs, plant bugs, stinkbugs, and water striders
Figure 18.12C
D. Order Coleoptera
– The order coleoptera includes
• Beetles
Figure 18.12D
E. Order Lepidoptera
– The order lepidoptera includes
• Moths and butter flies
Figure 18.12E
F. Order Diptera
– The order Diptera includes
• Flies, fruit flies, houseflies, gnats, and mosquitoes
Haltere
Figure 18.12F
G. Order Hymenoptera
– The order hymenoptera includes
• Ants, bees, and wasps
Figure 18.12G
Chapters 32- 34
The Animal Kingdom
Domain Eukarya
– Kingdom Animal
• Clade Deuterostome
• Phylum – Echinodermata
• Phylum - Chordata
Echinoderms have spiny skin, an endoskeleton,
and a water vascular system for movement
– Echinoderms, phylum Echinodermata
• Includes organisms such as sea stars and sea urchins
• Are radially symmetrical as adults
Tube foot
Tube foot
Spine
Figure 18.13B, C
– The water vascular system
• Has suction cup–like tube feet used for respiration and
locomotion
Anus
Spines
Tube feet
Canals
Stomach
Figure 18.13A
Invertebrate: Echinodermata Starfish, sea urchins, sea cucumber
– radially symmetrical
– spiny exoskeleton
The body plans of animals can be used to build
phylogenetic trees
– One hypothesis of animal phylogeny
• Is based on morphological comparisons
Ancestral
colonial protist
No true tissues True tissues
Bilateral symmetry Radial symmetry
Eumetazoans
Bilaterians
Protostomes Deuterostomes
Spo
nges
Cnid
aria
ns
Ech
ino
der
ms
Cho
rdat
es
Fla
two
rms
Mo
llusc
s
Annel
ids
Art
hro
po
ds
Nem
ato
des
Deuterostome Clade
Echinoderms (seastars and sea urchins) and
Chordates (Us) are monophyletic.
Protostomes make up two clades:
Lophotrochozoa and Ecdysozoa.
Lophotrochozoa are split into 2 groups:
Trochopore larva (annelida and mollusca)
and Lophophore bearing (flatworms, rotifers).
Ecdysozoans shed an old exoskeletons
(Nematodes and Arthropods).
Our own phylum, Chordata, is distinguished by
four features
– Chordates, phylum Chordata have
• A dorsal hollow ner ve cord
• A stiff notochord
• Pharyngeal slits
• A muscular post-anal tail
Vertebrate Evolution and
Diversity
Campbell’s Chapter 34
Vertebrates belong to Phylum
Chordata
Chordata also includes:
– Urochordates - Tunicates
– Cephalochordates - Lancelets
Vertebrates
– fish, amphibians, reptiles, birds, mammals
– internal bony skeleton
• backbone encasing
spinal column
• skull-encased brain
postanal tail notochord
hollow dorsal nerve cord
pharyngeal pouches
Chordata
becomes brain & spinal cord
becomes vertebrae
becomes gills or Eustachian tube
becomes tail or tailbone
Oh, look… your first baby picture!
All Chordates possess 1. Notochord - A rigid but flexible rod
between the digestive tube and the
dorsal nerve cord.
2. Dorsal hollow Nerve cord
3. Pharyngeal Slits
4. Muscular, Post-anal Tail
Chordate Characteristics
Subphylum
Urochordates –
tunicates - seasquirts
Cephaloch
ordate -
Lancelets
Transitional Species – 530 mya
Haikouichthys – A true vertebrate
Myllokunmingia - early vertebrate
Neural crest Forms from closing neural tube and will form
parts of the bones and cartilage of the cranium.
Agnathans – Jawless
Ostracoderms – 450-375 million years ago
Hagfish – slime-eels
Has a cranium but no jaws, teeth or
backbone.
Still has Notochord
Sea Lampreys
Have a cranium and a cartilaginous partial
wrapping around notochord.
No jaws or teeth.
Jaws evolved from Pharyngeal
slits supports.
Vertebrates: Fish salmon, trout, sharks
450 mya
Characteristics
– body structure
• bony & cartilaginous skeleton
• jaws & paired appendages (fins)
• scales
– body function
• gills for gas exchange
• two-chambered heart;
single loop blood circulation
• ectotherms
– reproduction
• external fertilization
• external development in
aquatic egg
gills
body
Chondrichthyes – includes
Sharks and rays Jawed fish with Catilaginous skeletons
Have teeth and a lateral line
Sharks have been around for more than 400
million years.
Sharks existed about 200 million years
before dinosaurs.
There are more than 375 species of sharks
living today.
Megalodon
Fake
Whale Shark – Largest extant
fish 30 – 40 feet
Osteichthyes – Bony fish have
Calcified endoskeleton
Operculum – gill covering
30,000 species
Water comes in mouth through pharynx and
out through the gills
Swim bladder is used for buoyancy and
came from lungs
Osteichthyes – Bony fish
Three Extant groups (classes)
– Actinopterygii – ray finned fish
– Actinista – Lobed finned fish
– Dipnoi - Lungfish
Actinopterygii – ray finned fish
Include commonly known fish like trout, perch and
flounder.
1. Skin secrete mucus that reduces drag
2. Have keratin scales
3. Most reproduce externally
4. Two Chambered heart
5. Ectothermic
Anatomy of typical Ray finned
fish
Actinista – Lobed finned fish
Walk on bottom with muscular fins
Coelacanth
Dipnoi - Lungfish
All living lungfish live in
the remnants of
Gondwana; Australia,
Africa and South America
Have an amphibian-like lung
Tetrapod evolution from fish
The split between fish and amphibians is
very blurry.
Lungfish and frogs breath the same way
Fossil
record
From fish to Amphibians
Tiktaalik
Fish with a
neck
Tibia
Femur
Fibula
Humerus Shoulder
Radius Ulna
Tibia
Femur Pelvis
Fibula Lobe-finned fish
Humerus
Shoulder
Radius
Ulna
Pelvis
Early amphibian
Acanthostega – tetrapod FISH
Ichthyostega
Class - Amphibians
Amphi (two) bios (lives) – spend part of
the time in water and part on land
1. Breath through lungs and moist skin
2. Eggs are laid in water and larva (tadpoles)
lose lateral line.
3. Ectothermic
4. Three Chambered heart
lung
buccal cavity
glottis closed
Vertebrates: Amphibian Amphi (two) bios (lives) – spend part of the time in
water and part on land
Characteristics
– body structure
• legs (tetrapods)
• moist skin
– body function
• lungs (positive pressure) & diffusion through skin for gas exchange
• three-chambered heart; veins from lungs back to heart
• ectotherms
– reproduction
• external fertilization
• external development in aquatic egg
• metamorphosis (tadpole to adult)
frogs
salamanders
toads
350 mya
Orders
– Order Urodela – (tailed ones) Salamanders
– Order Anura – No tails – frogs and toads
– Order Apoda – no legs – legless
Urodela
500 species
Lungless
Anurans
4,200 species
Lungless frog
Apodans
150 species
The Amniotes
Class – Mammals - you
Class – Testudines - turtles
Class – Sphenodontia - tuataras
Class – Squamata – snakes and lizards
Class – Crocodilia- crocodiles and alligators
Class – Aves - birds
Amniotic Egg
The egg has a shell that allows the animal to live
on land exclusively (although many have returned
to the water).
Extraembryonic membranes
– Allantois – disposal of waste
– Amnion – protects embryo and prevents
dehydration
– Chorion – Exhange gases for the embryo
– Yolk Sac – contains nutrients in yolk
Skull features separated the
Earliest Amniotes
Synapsids - (One opening behind temple)lead to
therapsids and mammals
Anapsids - (No openings on the temple of the skull)lead to
An extinct group of reptiles (and maybe turtles)
Diapsids – (two arches opening) Lead to the dinosaurs,
modern reptile, archesaurs and birds
Dimetrodon – a mammal-like reptile
Titanophoneus a dominant
Therapsid
Reptilian Heritage evident
Terrestrial adaptations:
– Keratin scales protect from dessication (drying out)
– Must get all air from their lungs.
– Fertilization is internal
– Ectothermic –absorb external heat but have behaviors that assist in temperature control.
– Three chambered heart
– The first radiation was based upon skull differences and happened about 250 MYA
Vertebrates: Reptiles Characteristics
– body structure
• dry skin, scales, armor
– body function
• lungs for gas exchange
• thoracic breathing; negative pressure
• three-chambered heart
• ectotherms
– reproduction
• internal fertilization
• external development in amniotic egg
250 mya dinosaurs, turtles
lizards, snakes
alligators, crocodile
embryo leathery shell
chorion
allantois yolk sac
amnion
The age of Reptiles
The Mesozoic Era saw a wide diversification of reptiles and their cousins the dinosaurs.
From 251 to 65 MYA
When the dominant amphibians and therapsids went extinct at the end of the Permian (also ending the Paleozoic Era) Dinosaurs took over.
Testudines Turtles – no openings in temples but other
factors do not link them to the other
anapsids.
Newly discovered fossil from China has shed light on how the turtle's shell
evolved.
The 220 million-year-old find, described in Nature journal, shows that the turtle's
breast plate developed earlier than the rest of its shell.
The breast plate of this fossil was an extension of its ribs, but only hardened skin
covered its back.
Diapsids split into
Lepidosauria – Extinct oceanic reptiles
– Sphenodontia
– Mosasaurs
– Plesiosaurs
– Ichthyosaurs
– Squamata – snakes and reptiles
Archosauria-
– Crocodilians
– Pterosaurs
– Ornithischia
– Saurischians
– Aves
Leptidosaurians
Class – Sphenodontia - tuataras
Last of a primitive reptile found only in
New Zealand
Archosauria
– Crocodilians
– Pterosaurs
– Ornithischia
– Saurischians
– Aves
Crocodilians
Alligators and Crocodiles
pterosaurs
Ornithschians – Herbivorous and extinct
Saurishians – Herbivorous and carnivorous
She’s a he!
Archaeopteryx
Vertebrates: Birds
Characteristics
– body structure
• feathers & wings
• thin, hollow bone; flight skeleton
– body function
• very efficient lungs & air sacs
• four-chambered heart
• endotherms
– reproduction
• internal fertilization
• external development in amniotic egg
150 mya finches, hawk
ostrich, turkey
trachea
anterior air sacs
lung
posterior air sacs
Birds are a branch of the
Saurischians
Birds
8,600 species
Ratite birds are flightless.
Form and function
Four chambered heart
Endothermic
Hatched from eggs
Vertebrates: Mammals Characteristics
– body structure
• hair
• specialized teeth
– body function
• lungs, diaphragm; negative pressure
• four-chambered heart
• endotherms
– reproduction
• internal fertilization
• internal development in uterus
– nourishment through placenta
• birth live young
• mammary glands make milk
(specialized sweat glands)
220 mya / 65 mya mice, ferret
elephants, bats
whales, humans
muscles contract
diaphragm contracts
Split into three groups from the
therapsids during the Mesozoic
The Monotremes – egg
layers
Marsupials – pouches
Eutherians – Placental
mammals
Marsupials versus Eutherians
Probably split ~125 MYA
Marsupials radiated in the southern
continents
Eutherians radiated in the northern land
masses and spread south.
A great deal of Convergent Evolution
Vertebrates: Mammals
Sub-groups
– monotremes
• egg-laying mammals
• duckbilled platypus, echidna
– marsupials
• pouched mammals
• short-lived placenta
• koala, kangaroo, opossum
– placental
• true placenta
• shrews, bats, whales, humans
Whale ancestor
Vertebrate quick check… Which vertebrates lay eggs with shells?
Which vertebrates are covered with scales?
What adaptations do birds have for flying?
What kind of symmetry do all vertebrates have?
Which vertebrates are ectothermic and which are
endothermic
Why must amphibians live near water?
What reproductive adaptations made mammals very
successful?
What characteristics distinguish the 3 sub-groups of
mammals?
2007-2008
That’s
the buzz!
Any
Questions?