Today: Exploring the Animal Kingdom Introduction to Ecology The Animal Kingdom- General Characteristics: Multicellular Heterotrophic (via ingestion) Eukaryotes Require Oxygen for aerobic respiration Reproduce sexually (and possibly asexually) Motile during part of the life cycle Life cycle includes stages of development Animal Body Plans Mostly INVERTEBRATES (no backbone) vs. VERTEBRATES (with backbone) Animal Body Plans: Symmetry Animal Body Plans: The Gut The GUT = a tube or sac projecting into the body where food is digested and absorbed Guts can be saclike with a single opening, or tubular with openings at two ends Animal Body Plans: Body Cavities Many animals have a cavity between the gut and the body wall called a COELOM. Coeloms allow animals to be larger and more complex by cushioning and protecting internal organs. 1
The Sponges Ancestral lineage- no true tissues No Symmetry An Evolutionary Overview of the Animals Lined with collar cells- create currents, trap food Skeleton composed of spicules The Sponges An Evolutionary Overview of the Animals The Cnidarians The Cnidarians Radially symmetrical Tentacled animals Mostly marine Have true tissues Make cnidocytes (stinging cells) 2
Bilateral Symmetry Earliest extensive organ-system development Nervous system with small brain Cephalization evident (eyespots!) Digestive track has single opening The Flatworms The Flukes: The Diversity of Flatworms Tapeworms: Tapeworms Planaria: The Roundworms Digestive tract complete Very Abundant! Ascaris: Trichinella: Vinegar Eels: 3
The Annelids (Segmented Worms) Also True Coelomates Most use bristles on each side of body for locomotion Nervous system, one-way gut Earthworm Primarily free-living (Lumbricus): Leeches: The Arthropods Segmented body, covered by exoskeleton Typically divided into 3 sections: the head, thorax, and abdomen More than 1 million identified species! Well-developed nervous system Three major existing groups of Arthropods: 1. Chelicerates (spiders) 2. Crustaceans (crabs and shrimp) 3. Insects Arthropod Diversity The Molluscs Bilaterally symmetrical, true coelom General body plan includes the head-foot, the visceral mass, and mantle (secretes shell) The Molluscs: Diversity Bivalves The Chitons The Cephalopods Gastropods ( belly foots ) 4
5-part body plan The Echinodermata Water vascular system w/tube feet Bilateral larvae w/ radial adults Spiny skin, internal skeleton The Chordates 4 Common Features: 1. Flexible supporting skeletal rod called a notochord 2. Dorsal hollow nerve cord above the notochord 3. Gill slits in the pharynx 4. Post anal tail The Invertebrate Chordates- Tunicates! No backbone Larval form has all four traits; sessile adult looks nothing like a chordate! The Chordates: The Vertebrates A bony spinal or vertebral column replaces the notochord, and encases the dorsal nerve cord Skull surrounds the brain Can be divided into Aquatic, Transitional, and Terrestrial Vertebrates The Aquatic Vertebrates Oldest= Jawless fish May have cartilaginous or bony skeleton 5
The Transitional Vertebrates (Amphibians) Incompletely adapted to terrestrial environments Dependent on water for reproduction Terrestrial Vertebrates Reptiles, Birds and Mammals Key Reptilian Evolutionary Innovations Tough, scaly skin to reduce water loss Internal fertilization Efficient kidneys Amniote eggs protect young The Chordates: Evolutionary Lineages Mammals Hair and Mammary Glands Behavioral Flexibility Modified Teeth Endotherms (high metabolic rates) Mammalian Lineages 1. Egg-laying mammals (monotremes) 2. Pouched Mammals (Marsupials) 3. Placental Mammals (eutherians) Spiny anteater- an egg-laying mammal Koalas- Marsupials Humans- Placental Mammals 6
What is Ecology?? Study of the interactions between organisms and their environment! Includes both biotic and abiotic components Can be studied at multiple levels: organismal ecology, population ecology, community ecology, ecosystem ecology Modeling Population Growth Ecologists use an equation to calculate the rate of population growth: When would a population really grow like this? Modeling Population Growth Logistic Growth Model is more realistic because of population-limiting factors. What kinds of factors might limit growth?? Modeling Population Growth Population growth might be limited by densitydependent factors or densityindependent factors Thinking About Ecology: Population Ecology One Common Goal: Zero Population Growth (ZPG) Thinking About Ecology: Population Ecology Demographers often calculate TFR (Total Fertility Rate) to help model a population s growth) 7
Thinking About Ecology: Population Ecology So what is the Earth s Carrying Capacity for humans? How could we determine it? Is it fixed? Have we already exceeded it? Thinking About Ecology: Population Ecology Another take on Carrying Capacity: Ecological Footprints Thinking About Ecological Footprints Brainstorm: What factors should you take into account when calculating an individual s ecological impact? http://www.myfootprint.org/ 8