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Test #1 Material
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What is an animal? 1. Mutlicellular, heterotrophic (get their own food), eukaryotes 2. Cells do not have cell walls 3. Have nervous and muscle tissues 4. Usually reproduce sexually These are characteristics of MOST animals.
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Reproduction 1. Sperm + Egg => 2. Zygote (fertilized egg) => 3. 8 cell ball (cleavage)=> 4. Blastula (hollow ball of cells) => 5. Gastrula
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Evolution of Animals Most scientists agree that the animal kingdom is: Monophyletic- came from a common ancestor Has branches where each adaptation comes in
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Parazoa “beside the animals” Has no true tissues Sponges
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Eumetazoa 2 branches based on symmetry Radial ex.) jellyfish and relatives has a top and a bottom no head or rear no left or right Bilateral Ex.) all other animals Has a top and bottom Has a head and a tail Has left and right sides
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Acoelomates Evolution of body cavities More complex animals Started without body cavities Ex. Flatworm
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Acoelomates Continued Then the insides were suspended in a fluid filled region and could move around without disturbing each other. Ex. Roundworms
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Protostomes and Deuterostomes During the gastrula phase the hollow ball developed a tube in the middle. In protostomes, the first opening becomes the mouth (clams, snails, squids, worms, crustaceans, insects, and spiders)
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Protostomes and Deuterostomes Continued In deuterostomes, the first opening becomes the anus (sea stars, sea urchins, and vertebrates)
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How Classification Began Classification – grouping of objects or information based on similarities Taxonomy – branch of biology for grouping and naming organisms Taxonomists – a biologists who studies taxonomy Aristotle Developed the first method of classification Grouped them into 2 groups: plants and animals His system was useful but did not group organisms according to their evolutionary history
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Classification Continued Linnaeus Developed method we still use today Based on structural and physical similarities of organisms Binomial nomenclature - gives each organism 2 names. The proper way to write a scientific name Example: animalia, vertebrata, mammalia, primata, hominidae, Homo sapien All letters are lower case except the genus is capitalized. Genus and species are underlined
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Animal classification Kingdom Largest Phylum Class Order Family Genus Species Smallest These groups are called taxa. Kings play chess on flat green stools.
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Scientific Names Scientific Names are written in Latin because: the language is no longer used the words stay the same and cannot change since the language is dead the words only have one meaning Common names are misleading because any organism can have multiple common names
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Dichotomous Key A set of paired statements used to help identify organisms Read each statement and decide which fits your organism Go to where that statement tells you and read the next two statements Eventually you will reach a statement that tells you the name of the organism
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Phylogenetic Classification Models Species that share a common ancestor also share an evolutionary history Phylogeny – the evolutionary history of a species Phylogenetic classification reveals the evolutionary relationships of species Cladistics System of classification that is based on phylogeny As groups of organisms diverge and evolve from a common ancestral group, they retain some unique inherited traits. Cladogram Branching diagram identifying a group’s derived traits. Similar to a pedigree or family tree. Two groups on diverging branches probably share a more recent ancestor than those groups farther away.
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Invertebrates
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Phylum: Porifera (sponges) Classes: 4 Orders: 18 Families: 80 Species: about 10,000 No tissues because cells are not specialized No nerves or muscles, but cells can sense and react to changes in the environment Of 10,000 species, 100 of those are in freshwater
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Porifera Sack of cells with pores Top opening is called the osculum-where water exits out of the sponge Water goes in through the pores called the spongocoel Under certain conditions, the cells contract and close all of the openings Filter feeders
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Porifera Reproduction Asexual Reproduction: Budding Can regenerate lost parts Can reproduce asexually from a broken piece of the parent Sexual Reproduction Hermaphrodites (have both male and female parts) Produces both sperm and egg Sperm shoots out into the water and is then taken back in (some sponges that are around cross are fertilized)
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Phylum:Cnidaria(hydras, jellies, sea anemonies, and coral) Classes:4 Orders:27 Families: 236 Species: 8,000-9,000 Have a single opening that is both the mouth and anus Sack with one digestive compartment
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2 Forms of Cnidarians Polyp (hydras and sea anemones) Tentacles push food into the mouth Medusa (Jellies) Tentacles have NEMATOCYSTS – stinging cells that grab and immobilize prey using toxins.
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Cnidarian Reproduction Asexually – budding (polyp form) Sexually –have separate male and female medusae that produce gametes that join through external fertilization
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Phylum: Platyhelmenthes (Flukes and Tapeworms) Classes: 4 Orders: 35 Families: 360 Species: 17,500 flatworms Some are microscopic and can grow to be up to 20 m long. Still only have one opening and one digestive cavity Absorb nutrients across their body surface
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Flukes Live as parasites in or on other animals Attach with suckers to internal organs or to the outer surface
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Tapeworms Also Parasites in or on other animals Head has suckers and hooks that lock into intestines Absorbs food digested by Humans Absorbs nutrients from digested food Eggs leave host in the feces
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Transmission This is why you shouldn’t drink contaminated water Some cows have the eggs in their muscles When we eat under cooked meat, you have a chance of contracting worms Can be 20m in length and can block intestines
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Flatworm Reproduction Sexually - Hermaphrodites – internal fertilzation. Asexually – fission – when damaged, regenerates new body parts.
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Phylum: Nematoda( pinworms & hook worms) Classes: 4 Orders: 25 Families: 185 Species: 20,000 Humans host about 50 species Also attacks animals and plant roots One species is called Trichinella spiralis causes trichinosis Caused by eating undercooked infected pork or other infected meat They can go into human muscles or other organs.
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Roundworm Feeding Have a simple digestive system. Have a mouth and an anus Parasitic roundworms use specialized structures (usually with hooks) to attach to a host.
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An Important Group Many nasty parasitic infections in humans, livestock
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Hookworm
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Phylum: Nemertea 1,200 species Probiscis worms or ribbon worms Can be marine, freshwater, or live in damp soil Size ranges from.5cm to over 50m Sexual and asexual reproduction Have a complete digestive tract & a closed circulatory system. Blood is enclosed in vessels Have no heart, but blood is propelled by muscles squeezing the vessels
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Phylum: Annelida Classes: 3 Orders: 31 Families: 130 Species: 12,000 Segmented worms (Annelida means “little rings”) From 1mm to 3 m > giant Australian earthworm
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Class: Oligochaeta Earthworm Divided by septa Digestive tract, blood vessels, and nerve cords penetrate septa and run the length of the body
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Oligochaeta Reproduction Hermaphrodites, but they cross fertilize 2 earthworms align and exchange sperm then they separate They store the sperm while an organ produces a mucous cocoon. The cocoon then slides along the worm and picks up the eggs, then the sperm The cocoon slips off the head and stays in the soil until it hatches
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Oligochaeta Reproduction They can also reproduce asexually by breaking apart They eat their way through the soil and absorb nutrients through the soil
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Class: Hirudinea Leeches Most live in fresh water, but some can live in moist vegetation Some feed on other invertebrates, but some are blood sucking parasites that feed by attaching to the host. Most abundant in the tropics. From 1-30cm long Hermaprodites but can cross fertilize Copulation is similar to the earthworm, by making cocoons and buries them in the dirt
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Feeding Some use blade like jaws to slit the skin of the host while others use an enzyme to digest a hole in the skin Host is usually unaware because the leech secretes an anesthetic Also secretes an enzyme (hirudin) that keeps the host’s blood from coagulating It then usually sucks as much blood as it can usually 10X it’s weight can usually last a month without another meal
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Human Benefits Was used by doctors for blood letting Still used to treat bruised tissue and to stimulate blood flow to reattached fingers and toes
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Phylum: Mollusca (Snails, slugs, oysters, clams, octopuses, & squids) Soft bodies but most are protected by shells All have 3 main body parts 1. Muscular foot usually used for movement 2. Visceral mass contains most internal organs 3. Mantle fold of tissue over a visceral mass that secretes a shell
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Class: Gastropoda (snails) Most are either male or female but many snails are hermaphrodites. Have spiral shells that the animal can retreat into Some have tentacles on their head w/ eyes at the tips Move by rippling the foot
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Class: Bivalvia (Clams, oysters, mussels, & scallops) Divided shells w/ a hinge Muscle pulls the halves together to protect the body When open, the foot comes out to move the animal or to dig. Water flows in through an incurrent siphon, passes over the gills then exits through an excurrent siphon They trap food in the mucous that lines the gills Secrete threads that attach them to rocks, docks boats, etc.
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Class: Cephalopoda (Squids, Octopuses) Carnivores Shell is reduced and internal in squids and is gone in octopuses Giant squids can be up to 17m long and can weigh 2 tons Cephalopods have well developed nervous systems and a complex brain and sensory organs.
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Cephalopoda Life Octopuses live on the sea floor. They creep and scurry searching for crabs and other food. They inject poison to immobilize the prey Mouth is at the center of the tentacles Squids move by shooting water out of an excurrent siphon (steers by pointing the siphon in different directions)
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General Characteristics Classes: 6 Orders: 36 Families: 145 Species: 6,000 Live in marine habitat Radial symmetry Larval stage has bilateral symmetry Body wall bears a number of spines, spicules, or plates made of calcium carbonate No brain Nervous system allows them to respond to information about feed, predators, etc. Phylum:Echinodermata
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Tube Feet – fluid filled muscular structures that have suckerlike adhesive disks Use tube feet for walking, burrowing, clinging to rocks or gripping a meal Water-Vascular System Unique to echinoderms A system of canals delivering water to tube feet Each tube foot has an ampulla – a fluid filled muscular structure shaped like a rubber bulb As an ampulla contracts, it forces fluid into the foot and causes it to lengthen
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Reproduction Sexes separate (few hermaphrodites) Large gonads No elaborate copulatory apparatus Fertilization usually external
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Class Asteroidea Starfish and sea stars Most have a flattened, flexible body with rays (often 5) arranged around a central disc The top side (aboral surface) contains the anus and the entrance to the water vascular system called a madreporite Sea stars swallow their prey whole Get rid of coarse undigested residues through the mouth. Anus is too small to get rid of clam shell
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1. Ambulacral Groove 2. Mouth
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1.Arm 2.Gonad 3.Stomach 4.Pyloric cecum
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Sand Dollars Flattened body in endoskeleton plates Burrow through sand for food Filter feed Mouth on oral surface and anus off to one side
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