invertebrates 2 - university of rio · pdf fileinvertebrates • animals that lack...
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Invertebrates 2Biology 2
Tuesday, March 12, 2013
Kingdom Animals
• Eukaryotic
• Multicellular - Many cell types
• Heterotrophic
• Feed by ingestion
• No cell walls
• Diploid life cycle
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Invertebrates
• Animals that lack backbones (95%)
• Porifera - pore-bearers
• Cnidaria - cnidocytes, polyps and medusa
• Ctenophora - ctenes
• Lophophorates - lophophore
• + others
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Phylogenetic Tree (fig 28.4)
Bilateral Symmetry Deuterostome
• no symmetry, no tissues - porifera
• radial symmetry, 2 tissues - cnidaria, ctenophora
• bilateral symmetry, 3 tissues - rest of animals
• protostomes
• lophophorates
• trophozoans - rotifers, platyhelmintes, molluscs, annelids
• ecdysozoans - nematodes, arthropods
• deuterostomes - echinoderms, chordates
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Phylum Platyhelminthes• “flat worms”
• single body opening (incomplete digestive tract)
• gastrovascular cavity
• primitive excretory system
• ladder-shaped nervous system
• reproductive organs
• some free-living e.g. Planaria
• some parasitic - e.g. Tapeworms and Flukes
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Parasitic Flatworms
• protective tegument (avoid digestion)
• less developed nervous system and sense organs
• complex life history, often involving several hosts
• examples - flukes, tapeworms
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Blood Fluke Schistosomafig 28.11
• male and female live together in blood vessels of intestine
• eggs pass from body in feces
• hatch in water into larva which enters snail
• goes through several larval forms in snail
• larva are released from snail
• burrow through skin of human and travel to intestine
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Tapeworm fig 28.12
• adult in human intestine
• body consists of head with suckers to attach to intestine followed by many segments with reproductive organs
• oldest segments are full of eggs, released in feces
• If eggs are eaten by pig, they hatch into larva. Larva form cysts called bladder worms in meat.
• If uncooked meat is eaten, larva hatch and grow into adult tapeworm.
• Tapeworms can reach several feet in length.
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Phylum Nematoda
• roundworms
• not segmented
• ecdysozoan - molt outer cuticle
• pseudocoelomate - have body cavity but muscle only on outside not around gut
• complete digestive system - mouth and anus
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Free-living Nematoda
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Parasitic NematodaAscaris
Intestinal ParasiteTrichinellaIntestine
Cyst in muscle
Wuchereriain lymph vessels
Elephantiasis
Guinea WormFemale releases eggs through sore in skin
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Phylum Rotifera• “wheel animals”
• corona (crown) of cilia
• microscopic
• pseudocoelomates
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Phylum Arthropoda• largest animal phylum (>1 million
species)
• “jointed leg”
• body segmented, fuse and specialize
• exoskeleton - chitin
• ecdysozoan - molt
• metamorphosis (larva-adult)
• coelomates - true body cavity (muscle both sides)
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Arthropod Diversity
Crustaceans
crayfish
Insects
SpidersCentipedes & Millipedes
brine shrimp
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Centipedes & Millipedes
• 1 pair legs per segment
• flattened body
• predators
• 2 pair legs per segment
• rounded body
• herbivores
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Crustaceans• exoskeleton hard (CaCO3)
• 5 or more pairs of appendages
• includes shrimp, lobster, crab, crayfish, many small aquatics
blue crab
barnaclepill bug
copepod
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Crustacean InternalCephalothorax Abdomen
Fig. 28.22
Heart & Vesselsopen circulatory system
Digestive Systemspecialization, muscles
Nervous System
Green Glandexcretion
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Insects
• largest group of arthropods
• 6 legs
• 3 body regions
• mostly land dwellers
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Insect InternalHead AbdomenThorax
Digestive System
Nervous System
Malpighian Tubulesexcretion
Trachearespiration
Fig. 28.25
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Insect DiversityBeetles Bees
GrasshopperButterfly
Flies
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Chelicerates
• spiders, ticks, scorpions
• 8 legs
• chelicera - pincers
• pedipalps - feelers
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Phylum Tardigrada
• water bears
• arthropod relative
• molts cuticle
• 8 stubby legs
• microscopic
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