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CHAPTER 12 INTRO TO ANIMALS (p. 330) There are over one million species and nine phylums.
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ANIMAL CHARACTERISTICS 1)cannot make their own food (must eat other organisms).
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2) must digest their food. - food must be broken down for the body to use.
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3)Must move from place to place. -find food, escape predators, migrate, find mates, etc. - called locomotion.
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4)must be multicellular. - many types of different cells.
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5)eukaryotic - must have a nucleus. 6) does not have cell walls.
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Vertebrates -animals which have a backbone. - provides support.
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The backbone also protects the spinal cord. - nerves which connect the body to the brain.
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Invertebrates -animals without a backbone. -97% of all animals are invertebrates.
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Some invertebrates have a hard shell for protection and support. Ex. clam Some have a hard outer skeleton for support. Ex. grasshopper
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Symmetry (P. 335) - the balanced arrangement of body parts around a center point or line. Radial Symmetry -arranged in a circle. Ex. jellyfish coral
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Bilateral Symmetry -it can be divided into two equal halves. -each side is the same All vertebrates and most invertebrates are bilateral.
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Dorsal - upper side Ventral - bottom side
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Anterior - front end Posterior - hind end
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Asymmetry -no way to divide the animal into halves Ex. sponges
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ASSIGNMENT: READ PP. 336 - 340.
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SIMPLE INVERTEBRATES (p. 346) Phylum Porifera Sponges -‘pore-bearing’ -found mostly on the bottom of shallow waters. - mostly salt water. - cannot move - sessile.
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Not a real sponge…
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-has pores -water enters and the sponge filters out unicellular organisms. -expels water thru a different pore - osculum -are called filter feeders
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-oxygen is absorbed the same way. -The simplest of animals. -two layers of cells. -no organs or tissues. Some once thought that sponges were plants.
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How my brother scratched my Dad’s 1960 Buick Electra Spicules -used for support. - a simple skeleton.
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Collar cells - pull water and food into the sponge.
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ASSIGNMENT WORKSHEET: “What is an Animal?”
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Asexual Reproduction in Sponges Regeneration - small parts break off and can grow into a ‘new’ sponge.
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Asexual Reproduction in Sponges Gemmules -are a hard outer covering with sponge cells inside. -created during harsh periods. - no food, low water levels.
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-when conditions improve, the gemmule breaks open and a ‘new’ sponge forms. (freshwater only - ocean conditions rarely change).
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Sexual Reproduction in Sponges -some species have separate sexes but most are hermaphrodites. - both male and female.
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- Sperm and eggs are released into the water where fertilization occurs. -it develops into a larva (young sponge) which has cilia to swim and find a spot to attach -- then it grows into a sponge.
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ASSIGNMENT WORKSHEET “SIMPLE ANIMALS”
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Phylum Cnidaria “stinging cells” (p. 339) Ex. jellyfish, coral, sea anemones. -once called Phylum Coelenterata - “hollow body” -more complex than sponges - but still simple. - no tissues or organs.
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-all have radial symmetry. -most have arm-like tentacles. -the tentacles have stinging cells called nematocysts.
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CORAL NEMATOCYSTS
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-the prey bumps into the nematocyst and is stunned. -the tentacles pull the prey into the mouth.
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Can be dangerous to people. Ex. Portuguese man-o-war
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Portuguese Man-o-war
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CORAL -have a hard outer skeleton. - when it dies, a new coral grows over the dead one building a reef.
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Cnidarians are the first animal to have a simple nervous system. -called a nerve net. - carries impulses and connects all parts of the organism,
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Cnidarians can have two body plans. (p. 339) 1)medusa - free-floating and often umbrella shaped. Ex. jellyfish
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2) Polyp -attached to a hard surface. -often tube shaped. Ex. sea anemone, coral
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Polyp Medusa Some species can alternate between body plans.
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ASSIGNMENT: WORKSHEET “Stinging Cells”
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Phylum Platyhelminthes “Flatworms” -flat bodies. -bilateral symmetry. -simple animals - but more complex than cnidarians. - absorb oxygen thru their skin.
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- most are parasites - but some are free-living. Ex. planaria (p. 345) -free-living -has an eyespot. - can sense changes in light.
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A planaria can regenerate body parts. - it has a simple nervous system in the shape of a ladder.
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A tapeworm is another example of a flatworm. (p. 346) -are parasites. - can enter the body by eating grass or uncooked meat which holds the tapeworm eggs.
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Tapeworms have hooks and sucker to attach to the intestine. -it absorbs the host’s digested food. - its ‘head’ is called a scolex.
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Each section is called a proglottid - and is full of eggs as it matures.
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ASSIGNMENT: QUESTIONS P. 335 2 - 3 P. 342 1 P. 349 2 - 3
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Phylum Nematoda “Roundworms” -largest worm phylum. -more complex than flatworms. - has a continuous digestive tract.
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“tube within a tube” mouth anus - excrete waste
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- some are parasites Ex. hookworm - it enters thru the skin - its larvae are very small. - it travels the blood system into the lungs.
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-A cough brings it up into the mouth -it is swallowed into the digestive system. - feeds on blood.
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Ex. Heartworm
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Ex. Trichinella worms -causes trichinosis - from eating uncooked pork.
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Another parasite is ascaris
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ASSIGNMENT: WORKSHEET “SIMPLE CREATURES’
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Phylum Annelidia “Segmented worms” “little rings” (p. 365) Ex. earthworm, leech -most advanced of the worms. - has a body cavity that holds organs.
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Earthworm Anatomy (p. 366) setae - tiny hairs on each segment. - for movement - to ‘hold on’ to the soil. Clittelum -thick band - used for reproduction.
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mouth DIGESTIVE SYSTEM - they ‘eat’ soil. cropgizzard intestine anus
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Crop - storage area. Gizzard - grinds the soil/organics. Intestine - breaks down food/absorbs nutrients. crop gizzard intestine
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Earthworms have a closed circulatory system. -the blood is contained in vessels. It has five ‘hearts’ called aortic arches to pump blood.
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- absorb oxygen thru their skin. - has a nervous system with a brain and a main nerve cord. ventral nerve cord intestine
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- are hermaphrodites. - have both male and female parts. - but must receive sperm from another worm. - it cannot fertilize itself.
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ASSIGNMENT: WORKSHEET “ANNELID ANATOMY”
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Leeches -are a parasitic segmented worm. -produce an anesthetic. - the host cannot feel the bite.
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A LEECH “MOUTH”
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- were once used to ‘bleed’ people with illnesses. - used today to keep blood flowing to reattached body parts.
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-Leeches have an anticoagulant in their saliva. -stops blood from clotting.
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ASSIGNMENT: WORKSHEET ‘CHAPTER REVIEW’
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