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animal that has no backbone

Cnidarian or Colenterate

invertebrates that have stinging cells to capture food and defend themselves; stinging cells are called nematocysts; sea anemone, jellyfish, hydra, and coral

Roundworm or Nematoda

has a digestive system that is like a tube, open at both ends; round worms, hookworms

Flatworm or Platyhelminthes

flat,wide and as soft as jelly; planarian, tapeworm, fluke

What planarians use to detect light


The reason sponges are first and Echinoderms are last in the invertebrate groups

Sponges are the simplest; and echinoderms are the most complex

Simplest organism with a brain?


Bilateral Symmetry

sense organs are in the front, distinct front and back, have more organs, more efficient

Radial Symmetry

Live in water, no specific head or tail, moves slowly

Segmented Worms or Annelida

body is made up of many linked sections called segments; earthworms, leeches, bristleworms

Sponge or Porifera

Invertebrates animals that have no body symmetry, never have tissue or organs, one opening; barrel sponge, elephant sponge

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