Animal Evolution and Diversity
Biology 201
What is Life?
Characteristics of Life
1. They have organization.
2. They regulate themselves.
3. They grow and develop.
4. They have metabolism.
5. They are irritable.
6. They reproduce.
7. They evolve.
Organization (Order)
• All living things:– Complex organized structures
made of cells– Chemically based on carbon
Regulation• 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
• Acquire materials and energy from external environment and convert them into to different molecules to maintain life.
Metabolism
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
Ecosystems
Community
Biomes
Populations
Organism
Organ system
OrgansTissues
Cells
Molecules
Atoms
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 CambriumWho is your ancestor?
Four key Events in Animal Evolution1. 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
(Coelomates)
Body cavities (coeloms)allow organs to moveindependently form bodyand may act as a hyrdostaticskeleton
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
• Domains: Eukarya, Bacteria, Archae
• Bacteria and Archae are prokaryotes
• Eukarya is divided on the basis of complexity and method of nutrition
EukaryaFungiPlantae Animalia
Protista
Bacteria
Archae
Eukarya
Modes of Nutrition
Autotrophs
Photosynthetic or chemosynthetic
HeterotrophsPhoto-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
Corals
Anemones
Medusans
Lion’s Mane Jelly
Purple Stripe Jelly
A Comb Jelly
Cnidocytes
Typical Cnidarian Life Cycle
• all tissues present, some head development, bilateral symmetry
• gastrovascular space, no body cavities
• Includes free living and parasitic species (flukes and tapeworms)
Platyhelminthes
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
Scolex
Proglottids
Nematodes
• have tissues, bilateral, • pseudocoeloms, complete gut• separate sexes• most parasitic includes pinworms
and hookworms• second most abundant animal
phylum
Nematodes
• 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
Trichinosis
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 Christmas Tree Worm
Clam 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• Internal or no shell• Most can produce ink• Use siphon for propulsion• Foot modified into tentacles
• 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)
Jointed Leg Animals
Typical Anatomy• Specialized appendages, one
pair per body segment• Hard chitin exoskeleton
– 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, tickshorseshoe crabs, and mites-specialized feeding appendage (chelicera)
3. Crustacea –crabs, lobsters, crayfish, isopods
4. Uniramia –insects, millipedes, and centipedesInsects 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• Mainly marine, few
freshwater and one terrestrial• Have a cephalothorax and
abdomenLobster
Centipedes
• 2 pairs of legs per body segment• Can produce a foul smelling
fluid• Can roll up into spiral• herbivores
Millipedes
• 1 pair of legs per body segment
• Fast predators• poisonous
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
• 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.
Primitive Invertebrate Chordates
Can you spot your ancestor?
Possible Chordate AncestryPre-chordate
• Sessile arm feeder• Bilateral, ciliated larva (BCL)
Living Relatives
(starfish)
Echinoderms(esp. crinoids)
Hemichordate-like• Sessile, ciliated arm feeder with
BCL• Gill slits for better feeding• Appearance of pre-notochord• Some metameric muscle in larva
Hemichordates:acorn worms; pterobranchs
• 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 larvaUrochordata:tunicates
Primitive vertebrate
• All chordate characteristics present• Development of kidney and other
organ systems• Extensive segmental musculature• Motile filter feeder
Cephalochordata:amphioxus
neoteny
Protochordates