Animal kingdom groups (phyla)

What is an animal? Heterotroph (consumer, not decomposer) Multicellular Eukaryote No cell wall (unlike fungi, plants, and bacteria) Specialized cells (unlike protists)

Evolution of complexity Need: sense and chase down food source Adaptation: nervous / motor systems Need: break up food and absorb nutrients Adaptation: digestive system Need: deliver oxygen to all cells Adaptation: circulatory / respiratory systems

Sponges

Sponges O2 and food come in through diffusion Filter feeds as an adult

Sponges Unique among animal groups – No symmetry in overall body plan No tissues (complex organization of cells)

Sponge reproduction Sexual – release sperm into water (external fertilization very common in aquatic animals) Hermaphroditism – sponges have sperm AND eggs to increase the odds of reproduction Offspring can swim to a new location Asexual fragmentation also possible

Sponges Simplest animals Possible colonial protozoan ancestor

Cnidarians Sea anemone Jellyfish

Evolution of radial symmetry Definiton – can cut in equal halves more than one way Ex: letters “O”, “X” Purpose – extending tentacles equally in all directions (increase food uptake)

Cnidarian Basic digestive system Also basic nervous system (nerve net) O2 still enters by diffusion

Revolution #1 – active movement Filter feeding will not be sufficient for larger animals Filter feeding will not work on land or in air 2 major adaptations to help organisms sense and move in their environment

Adaptation #1) Body symmetry Bilateral symmetry allows for development of brain region in a central location (head) Bilateral symmetry  cephalization

Adaptation #2: Body cavity Coelom is a space inside body (empty / fluid) Two purposes in evolutionary history: a) Short-term: something for muscles to push against to move b) Long-term: space for larger organs Not present in all animals (some have lost over evolutionary time)

Revolution #1 – active movement Cephalization = “command center” to coordinate senses and movement + Coelom = support for muscle movement

Flatworms Planarian – not parasitic Tapeworm – parasitic

Trends in flatworms No coelom Why? Many are parasitic O2 and sugar absorbed in host’s intestine

Tapeworm life cycle

Roundworms hookworm -- parasitic

Trends in roundworms Semi-developed coelom (moves a bit more) Can burrow through skin (walking around barefoot), also enters through contaminated food

Not a problem in U.S.

Why not? Food safety inspections Good sanitation Medication widely available

Mollusks Clam – 2 shells Snail – 1 shell Squid – no shell

These are all in the same group!?! inside of a clam

Mollusk traits Getting food – filter feeders (clams), grazers (snails), predators (slugs) Getting O2 – gills in aquatic mollusks, primitive lung in snails Open or closed circulatory system

Open vs. closed Open Closed No blood vessels Blood vessels Blood surrounds body’s organs, delivers O2 Smaller animals Closed Blood vessels Larger animals

Reproduction Hermaphrodites (both mollusks and segmented worms) Aquatic – release sperm and eggs into water Land – meet and swap sperm, fertilize eggs inside

Segmented worms leech earthworm

Segmented worms Full coelom (full range of motion, complex organs inside) O2 – Gets O2 directly from moist skin, closed circulatory system with hearts to deliver Food – blood (leeches), or dirt (earthworms)

Earthworms rule Swallow dirt, filter out food Loosen soil, helps to aerate soil for plants Also fertilizes plants with castings (poop)

Leeches rule Two chemicals in saliva to help it take blood from hosts Anesthetic Anti-coagulant

Revolution #2 - skeletons Structural support for larger bodies (remember, no cell walls in animal cells) Two varieties: 1) Exoskeleton – outside body (arthropods) 2) Endoskeleton – inside body (echinoderms, chordates)

Arthropods Four main classes within this HUGE phylum: Arachnids Crustaceans Centipedes / millipedes Insects

Arachnids Black widow Brown recluse

Arachnids Chigger (flea) Tick Scorpion

Crustaceans Crab Lobster Barnacles

Many-footed ones Centipede Millipede

Insects Wasp Fire ants Grasshopper

Arthropod traits Exoskeleton Coelomate (I will also stop writing this now) Segments still (possible connection to segmented worms) Exoskeleton

Exoskeleton NOT the same as mollusk shell Functions: 1) protection, 2) prevent water loss on land (waxy layer) Problems: Heavy, growth requires molting Therefore: arthropods tend to be smaller

For respiration… System for collecting O2 (tracheal tubes / spiracles) Open circulatory system

Complex nervous system Sophisticated sensory / motor control Compound eye of a fruit fly

Arthropod reproduction Internal fertilization (mating) in land arthropods External fertilization in sea arthropods

Echinoderms sea urchin sea star sea cucumber

Echinoderm traits adults = radial symmetry (live on ocean floor) larvae are bilaterally symmetric endoskeleton

Echinoderm traits Food – variety of diet (some eat clams, some eat algae, some filter feed) Water vascular system (water instead of blood to carry O2) Reproduction typical in water

Chordates

All chordates Have notochord – precursor to vertebral spinal column (semirigid, filled with fluid) Vertebrates replace this with a full spinal cord Some chordates are invertebrates still

Invertebrate chordates lancelet tunicate

Endoskeleton advantage Organisms can grow larger with skeleton inside