Transcript Unnumbered Figure

Animal Evolution
and Diversity
Biology 201
What is Life?
Characteristics
of Life
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They have organization.
They regulate themselves.
They grow and develop.
They have metabolism.
They are irritable.
They reproduce.
They evolve.
Organization (Order)
• All living things:
– Complex organized structures
made of cells
– Chemically based on carbon
Regulation
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Maintain a consistent internal environment
Some will be able to homeostatically control their internal environment
Ex. Reflexes (positive and negative feedback)
What are some of the parameters controlled inside living things?
Grow and Develop
Metabolism
• Acquire materials and energy from
external environment and convert
them into to different molecules to
maintain life.
Irritable
• Respond to stimuli from both
living and nonliving sources
Reproduce
• Pass on biological information to
succeeding generations
• Genes and DNA
Life Evolves
• Species change over time to
better adapt to their
environment
Levels of
Complexity
Biosphere
Biomes
Ecosystems
Community
Populations
Atoms
Organism
Organ system
Molecules
Cells
Organs
Tissues
Animal Trivia
•Heart is the size of a average car.
•Largest BV you could swim inside.
•Tail fluke is the width of a small aircraft.
Animal
Lineage
• multicellular eukaryotic
heterotrophs
• ingest their food with
internalized digestion, store
CHO as glycogen
• most reproduce sexually
• share common development
• most have tissues (muscle,
nerves, etc.)
Development
• most form zygote from
fertilized egg
• after much cell division
(cleavage) ball of cells
form hollow ball 
blastula
• grows and rearranges into
gastrula (2-3 layered
embryo) formation of germ
layers which give rise to
tissues and the gut
• may develop directly into
adult body but many form
larva that undergoes
metamorphosis into adult
Metamorphsis
• Larva may look and behave
very differently than adult
• Change to adult completed
while in pupal stage
Development may Reflect
Evolutionary History
• early protist ancestor was probably colonial flagellate
• cell specialization aided colony behavior
• rearrangement of colony shape allowed further cell
specialization and the development of tissues and organs
Artists conception of the Cambrium Sea (540 mya)
The Cambrian Explosion
All animal phyla were well developed by late Cambrium
Who is your ancestor?
Four key Events in Animal Evolution
1. Development of tissues -cell lines with
specific functions
2. Radial vs. Bilateral Symmetry
3. Development of body cavities
4. Protostome vs. Deutrostome developmental
patterns
Symmetry
Body
Cavities
Body cavities (coeloms)
allow organs to move
independently form body
and may act as a hyrdostatic
skeleton
(Coelomates)
Protostome vs.
Deuterostomes
• the first hole that
forms gut is either
the anus or the
mouth
• Protostomes form
the mouth first
• Deuterstomes form
anus first
Classification of
Life Forms:
Three Domains
Eukarya
• Domains: Eukarya,
Bacteria, Archae
• Bacteria and Archae are
prokaryotes
• Eukarya is divided on the
basis of complexity and
method of nutrition
Fungi
Plantae
Eukarya
Protista
Bacteri
a
Archae
Animalia
Autotrophs
Photosynthetic or
chemosynthetic
Modes of
Nutrition
Heterotrophs
Photo-heterotroph
Chemo-heterotroph
-absorbers
-digesters
• sessile adult filter feeders
• flagellated larvae, no
tissues
• all aquatic, most marine
• types based on composition
of skeletal elements
Sponge Body
Sponge Types:
glass, carbonate and spongin sponges
• corals, anemones, hydras and jellies
• two sets of tissues, radial symmetry
• archenteron (gastrovascular cavity)
surrounded by tentacles
• tentacles have cnidocytes (stinging
cells)
• two body forms: polyp and medusa
(some alternate)
Body Forms
Polyps
Anemones
Corals
Purple Stripe Jelly
Medusans
Lion’s Mane
Jelly
A Comb Jelly
Cnidocytes
Typical Cnidarian Life Cycle
Platyhelminthes
• all tissues present, some head
development, bilateral symmetry
• gastrovascular space, no body
cavities
• Includes free living and parasitic
species (flukes and tapeworms)
Body Form
• flattened body, organs and
organ systems present
• hermaphroditic
• incomplete gut (one
opening only)
Cestoda:
Tapeworms
• two hosts: herbivore and predator
• each proglottid is male and female and is
a reproductive factory producing 1000s
of eggs
• little organ systems
• see life cycle
Proglottids
Scolex
Nematodes
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have tissues, bilateral,
pseudocoeloms, complete gut
separate sexes
most parasitic includes pinworms
and hookworms
• second most abundant animal
phylum
Nematodes
Trichinosis
• tough outer cuticle, have
gastrointestinal tract but no
circulatory system
• show no segmentation and
have only longitudinal
muscles
• may lay more than 100,000
eggs a day
Heartworms
Segmented
Worms
• highly segmented body separated by septum
• has tissues, coelom, bilateral, complete gut
• closed circulatory system and extensive
nervous system
• 3 classes: earthworms, polychaetes, and
leeches
Earthworm Anatomy
Annelid
Diversity
Annelid
Diversity
Clam Worm
Christmas Tree Worm
Annelid
Diversity
Molluscs
• Triploblastic, coelomate, complete gut,
bilateral
• Soft body, mostly aquatic (or very moist)
• Most have shell secreted by mantle
Body Plan
• Foot –muscular locomotion organ
• Visceral Mass –internal organs
• Mantle –covers visceral mass, secretes
“mother of pearl”
• Most have rasping tongue -radula
Gastropods
–snails and slugs
• Glides on foot
• Body grows with torsion
• Most herbivorous
Bivalves
–clams, scalops, oysters, and mussels
• Filter feeders using gills
• Two half shells with hinge
Cephalopods
-squids, octopus, nautilus
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Internal or no shell
Most can produce ink
Use siphon for propulsion
Foot modified into tentacles
Jointed Leg
Animals
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most successful group of animals to ever live
segmentation with high degree of specialization
exoskeleton made of chitin
Extensive sensory structures
Open circulatory system (hemolymph)
Typical Anatomy
• Specialized appendages, one
pair per body segment
• Hard chitin exoskeleton
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Useful in protection
May be highly modified
Serves as muscle attachment
Impermeable to water
Most be molted to allow growth
Molting
Four Major Groups
1. Trilobytes –extinct
2. Chelicerates
-spiders, scorpions, ticks
horseshoe crabs, and mites
-specialized feeding appendage (chelicera)
3. Crustacea –crabs, lobsters, crayfish, isopods
4. Uniramia –insects, millipedes, and centipedes
Insects make up the largest class of animals
Chelicerates
• Horseshoe crabs represent an
ancient order of arthopods
• Arachnids include scorpions,
spiders, mites and ticks
Spiders
• 8 legs, chelicera
modified into fangs
• Poisonous
• Produces web
Crustaceans
Lobster
• Mainly marine, few
freshwater and one terrestrial
• Have a cephalothorax and
abdomen
Centipedes
• 1 pair of legs per body
segment
• Fast predators
• poisonous
Millipedes
• 2 pairs of legs per body segment
• Can produce a foul smelling
fluid
• Can roll up into spiral
• herbivores
Insects
• Head, thorax and
abdomen
• 6 walking legs
• 2 pair of wings )only
invertebrate able to fly
• Extreme diversity
Echinoderms
• Deuterostomes, radial symmetry in adult
• Bilateral larva
• Endoskeleton with spines that protrude
through skin
• Water vascular system with tube feet
Sea Star Anatomy
Feeding Star Fish
Echinoderm
Diversity
Sea Lilies
Chordates
• Deuterostome, bilateral, coelomate
• Complete gut, closed circulation
• Includes the vertebrates (back boned
animals)
Characteristics of all Chordates
Must be present sometime during life cycle
Primitive
Invertebrate
Chordates
• upper pictures: Tunicates look
chordate like only as a larva, otherwise
they are sessile filter feeders
• Right: Lancelets are poor swimmers
but burrow in loose sand easily, filter
feed to survive. An animal similar to
these led to all vertebrates.
Can you spot your ancestor?
Possible Chordate Ancestry
Living Relatives
Pre-chordate
•Sessile arm feeder
•Bilateral, ciliated larva (BCL)
(starfish)
Echinoderms
(esp. crinoids)
Hemichordate-like
Hemichordates:
acorn worms; pterobranchs
•Sessile, ciliated arm feeder with BCL
•Gill slits for better feeding
•Appearance of pre-notochord
•Some metameric muscle in larva
Protochordates
Urochordata:
tunicates
neoteny
•Loss of tentacles
•Post-anal tail development
•Some metameric muscles
•Tadpole like larva; more time
spent as larva
•Notochord and dorsal hollow nerve
cord in larva
Primitive vertebrate
Cephalochordata:
amphioxus
•All chordate characteristics present
•Development of kidney and other
organ systems
•Extensive segmental musculature
•Motile filter feeder