Primitive Critters

Porifera

Porifera - Body Plan

Cnidaria - body forms

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Ctenophora

Ctenophora

Ctenophora

Platyhelminthyes

Parasitic Flatworms - Tapeworms

• Parasites have adaptations for attaching to their host as well as adaptations for evading the hosts immune defenses

• Tapeworms also have intermediate hosts. In humans the intermediate host may be a pig or cow. Fleas are the intermediate host of the dog tapeworm.

Parasitic Flatworms - Flukes

• Parasites often cause chronic debilitating diseases

• Their life cycles are often complex and may involve more than one host

Nemertae

• Also called proboscis worms. The extendable probocis is used to capture prey.

• Their body is much like a flatworm, but with an intestine, anus, and circulatory system.

Nematoda

• Nematodes, also called roundworms have a one way digestive system and a tube within a tube body design.

• The space between the two tubes is a type of body cavity called a pseudocoelom.

C. elegans

Trichina

Annelida - Segmented Worms

Playground Playmate?

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Trochophore Larva

Mollusk Body Plan

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Peripitus

Arthropoda

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EARLY DEVELOPMENT

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