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Invertebrates 2
Biology 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)
• 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 Schistosoma
fig 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 Nematoda
Ascaris
Intestinal Parasite
Trichinella
Intestine
Cyst in muscle
Wuchereria
in lymph vessels
Elephantiasis
Guinea Worm
Female 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
Centipedes & Millipedes
Crustaceans
crayfish
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brine shrimp
Spiders
Insects
Centipedes & Millipedes
•
• flattened body
• predators
1 pair legs per segment
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• 2 pair legs per segment
• rounded body
• herbivores
Crustaceans
• exoskeleton hard (CaCO )
• 5 or more pairs of appendages
• includes shrimp, lobster, crab,
3
crayfish, many small aquatics
blue crab
copepod
pill bug
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barnacle
Crustacean Internal
Cephalothorax
Green Gland
excretion
Abdomen
Heart & Vessels
open circulatory system
Fig. 28.22
Nervous System
Digestive System
specialization, muscles
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Insects
• largest group of arthropods
• 6 legs
• 3 body regions
• mostly land dwellers
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Insect Internal
Head
Nervous
System
Abdomen
Thorax
Fig. 28.25
Digestive System
Malpighian Tubules
excretion
Trachea
respiration
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Insect Diversity
Flies
Beetles
Butterfly
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Bees
Grasshopper
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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