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Invertebrates. Animal Characteristics. All organisms in this kingdom have these common characteristics: Multicellular Eukaryotes No cell wall- unlike fungi, plants, bacteria Heterotrophs – consumer not decomposer Have Specialized Cells- unlike protists. Needs of Animals.
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Animal Characteristics • All organisms in this kingdom have these common characteristics: • Multicellular Eukaryotes • No cell wall- unlike fungi, plants, bacteria • Heterotrophs– consumer not decomposer • Have Specialized Cells- unlike protists
Needs of Animals • 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
SYMMETRY • Asymmetry – no symmetry • Radial symmetry - can cut in equal halves-more than one way • Bilateral symmetry – allows for development of brain region in a central location (head)
Types of Symmetry Asymmetry
Background: different types of body symmetry *Usually simpler organisms *Usually more complicated organisms
Bilateral Symmetry They all have a head area with sense organs
Development of Organisms • Develop from a single cell, the zygote • Mitosis forms new cell in a process called cleavage • A hollow ball of cells are formed called a blastula • Gastrulation is the folding in of the blastula to form two layers • These two layers are the ectoderm and the endoderm
Development • Ectoderm develops into skin and nervous tissue • Endoderm develops into the lining of the digestive tract and organs associated with digestion • In some animals the gastrula forms a mesoderm • Mesoderm is the third layer and develops into muscles, circulatory, excretory, and respiratory systems
Development • Protostome is an animal with a mouth that develops from the opening in the gastrula called the blastopore • Deuterostome The anus develops from the opening in the gastrula
Body Plans • Acoelom- do not have a body cavity, organs are imbedded in tissues • Pseudocoelom -(partial) a body cavity partly lined with mesoderm • Coelom- a body cavity that provides space for the development of internal organs (something for muscles to push against to move)
Vertebrate vs Invertebrate • Vertebrate- has a backbone • Invertebrate- has NO backbone
Exoskeleton • Functions: • Protection • Prevents water loss on land (waxy layer) • Problems: • Heavy • Growth requires molting
Endoskeleton • An internal skeleton that provides support inside the body • Advantage: Organisms can grow larger with skeleton inside
Sponges • Simplest Animals • Asymmetry
Sponges • Sessile - do not move • Asymmetrical • No tissue (Only organized cells)
Sponges • Oxygen and food come in through Diffusion • Filter Feeds as an adult
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
Cnidarians Sea Anemone (Polyp) Jellyfish (Medusa)
Cnidarians • Evolution of Radial Symmetry • Extends tentacles equally in all directions (increase food uptake)
Cnidarian Characteristics • Basic digestive system • Also basic nervous system (nerve net) • O2 still enters by diffusion
Cnidarian Characteristics • Reproduces sexually and asexually • Skeleton-none present, but dead coral remains are calcium carbonate
Flatworms-Platyhelminthes Planarian – not parasitic Tapeworm – parasitic
Flatworm Characteristics • No coelom – Why? Many are parasitic • O2 and sugar are absorbed in host’s intestine • Bilateral symmetry • Reproduction-most are hermaphrodites
Flatworm or Planaria Fresh Water Planaria Uses Pharynx to obtain food Salt Water Flatworms
Roundworms hookworm - parasitic
Roundworms • Smooth, non-segmented body • Pseudocoelom (moves more) • Can burrow through skin (walking around barefoot) • Also enters through contaminated food
Roundworm CharacteristicsMore Advanced • Bilateral symmetry • Complete digestive system with mouth and anus • Sexual reproduction • Oxygen enters by diffusion
Hookworms, Pinworms, Tapeworms that were removed from a Brazilian boy treated on a Rockefeller foundation mission (early 1900’s) These parasites still affect people all over the globe.
Why not? • Food safety inspections • Good sanitation • Medication widely available
Roundworms Dirofilaria is a roundworm that causes heartworm disease in dogs.
Ascaris: a parasitic roundworm Other Roundworms
Other Roundworms The roundworm is carried by mosquitoes in tropical Africa Elephantiasis results when a roundworm blocks the lymphatic system, causing severe swelling
Roundworms: Hookworms Hookworms attached to the intestines
Segmented Worms Earthworm leech
Segmented Worm Characteristics • Bilateral symmetry • Full Coelom (full range of motion, complex organs inside) • Complete digestion system • Most are hermaphrodites with sexual reproduction
Segmented Worm Characteristics • Gets O2 directly from moist skin, • closed circulatory system with hearts to deliver • Food – blood (leeches), or dirt (earthworms)
Earthworms Giant Earthworm Regular Earthworm
Earthworms • Swallow dirt, filter out food • Loosen soil, helps to aerate soil for plants • Also fertilizes plants with castings (poop)