Invertebrates 2 - University of Rio · PDF fileInvertebrates • Animals that lack...

Invertebrates 2Biology 2

Tuesday, March 12, 2013

Kingdom Animals

• Eukaryotic

• Multicellular - Many cell types

• Heterotrophic

• Feed by ingestion

• No cell walls

• Diploid life cycle


Invertebrates

• Animals that lack backbones (95%)

• Porifera - pore-bearers

• Cnidaria - cnidocytes, polyps and medusa

• Ctenophora - ctenes

• Lophophorates - lophophore

• + others


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


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


Parasitic Flatworms

• protective tegument (avoid digestion)

• less developed nervous system and sense organs

• complex life history, often involving several hosts

• examples - flukes, tapeworms


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


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.


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


Free-living Nematoda


Parasitic NematodaAscaris

Intestinal ParasiteTrichinellaIntestine

Cyst in muscle

Wuchereriain lymph vessels

Elephantiasis

Guinea WormFemale releases eggs through sore in skin


Phylum Rotifera• “wheel animals”

• corona (crown) of cilia

• microscopic

• pseudocoelomates


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)


Arthropod Diversity

Crustaceans

crayfish

Insects

SpidersCentipedes & Millipedes

brine shrimp


Centipedes & Millipedes

• 1 pair legs per segment

• flattened body

• predators

• 2 pair legs per segment

• rounded body

• herbivores


Crustaceans• exoskeleton hard (CaCO3)

• 5 or more pairs of appendages

• includes shrimp, lobster, crab, crayfish, many small aquatics

blue crab

barnaclepill bug

copepod


Crustacean InternalCephalothorax Abdomen

Fig. 28.22

Heart & Vesselsopen circulatory system

Digestive Systemspecialization, muscles

Nervous System

Green Glandexcretion


Insects

• largest group of arthropods

• 6 legs

• 3 body regions

• mostly land dwellers


Insect InternalHead AbdomenThorax

Digestive System

Nervous System

Malpighian Tubulesexcretion

Trachearespiration

Fig. 28.25


Insect DiversityBeetles Bees

GrasshopperButterfly

Flies


Chelicerates

• spiders, ticks, scorpions

• 8 legs

• chelicera - pincers

• pedipalps - feelers


Phylum Tardigrada

• water bears

• arthropod relative

• molts cuticle

• 8 stubby legs

• microscopic


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