Animals: Worms-flat, round & segmented

Ch 33

Invertebrate Diversity

I. Evolutionary innovations in sponges & cnidariansA. Presence or absence of tissuesB. Radial symmetry

II. Worms - flat and roundA. Parasitic adaptations in worms

III. Adaptive radiation in molluscs (how body plan reflects habitat and way of life)

IV. Why are arthropods so successful?V. Evolution of chordates

A. Vertebrates

BodyCavities

Acoelomate

Pseudocoelomate

Coelomate

Protostomes vs. Deuterostomes

Radiata

Eumetazoa

Metazoa

Porifera

Bilateria

*

Platyhelminthes(Flatworms)

Lophotrochozoa

Platyhelminthes

• True tissues • Bilateral symmetry• What goes along with this?

20,000 spp.20,000 spp.

• Acoelomate• Protostomes• 3 embryonic germ layers

Platyhelminthes

http://www.pbs.org/kcet/shapeoflife/episodes/hunt_explo2.html

Cross fertilize

Mesoderm -> muscle layer

eyespots

Free living Planaria sp.

Parasitic adaptations

1. Attachment

2. Reproduction --> hypertrophy of reproductive organs

PlatyhelminthesParasitic

FlukeTapeworm

Similar to33.8

Hooks & suckers

Scolex

Tapeworm

proglottidSimilar to Fig. 33.7

Platyhelminthes

Complex life cycle -Intermediate hosts - cattle, fish & pigsDefinitive host - human (final host)

7 sp. Human tapeworms

Can be 25 meters long

Most common - beef tapewormcysts in muscles of cattle undercooked meat -> attaches to intestine

Human tapeworm

Pig tapeworm

Some symptoms:

From bulk of worm and toxic excretory products

Radiata

Eumetazoa

Metazoa

Porifera

Bilateria

*

*NematodaPseudocoelomate

Protostome

LophotrochozoaEcdysozoa

NematodaTrue Tissues Bilateral SymmetryPseduocoelomateProtostomes

> 100,000 spp.Important in recycling nutrients -

decomposers

Also plant parasites e.g., potatoes, soybeans, onions

Animal parasites e.g., roundwormsheartworms, hookworm,

Most free living

Parasitic Nematodes

Roundworms - Ascaris sp.HookwormsHeartwormsPinwormsWhipwormsGuinea worm

Canid roundworm

Canidwhipworm

Hookworms

magnified many times -- thank goodness!

Heart and pin worms

Heartworms

Pinworms

Elephantiasis

Caused by filarial worm

Guinea Worm

Radiata

Eumetazoa

Metazoa

Porifera

Bilateria

*

*AnnelidaCoelomateProtostome

Lophotrochozoa

True Tissues Bilateral SymmetryCoelomateProtostome

P. Annelida

16,500 spp.

http://www.pbs.org/kcet/shapeoflife/episodes/explo_explo2.html