Simple Invertebrates• Sponge • Sponges are

asymmetrical• and do not have real

tissue or organs.

• Cnidarians have radial symmetry

• and have a mouth, tentacles, muscle tissue and stinger cells

sponge

jellyfish

Sea anemone

hydra

coral

Simple Invertebrates

• Flatworm -flat body, head with simple eyes, and a mouth

• Roundworm-simple digestive and nervous system

• Segmented worm-divided into sections and has organs such as a heart, stomach, and brain

Flatworm

Roundworm(nematode)

Segmented worm(annelids)

Complex Invertebrates -Mollusks• Snails • have bilateral

symmetry• a muscular foot or

tentacle• mass of internal

organs• most have a shell• specialized organs

including heart, gills and a well-developed nervous system

Snails

clams

squid

Complex Invertebrates-Echinoderms

• have a hardened skeleton inside the body (endoskeleton)

• usually have radial symmetry

• use a water pressure system that helps them feed, breathe and move

Sea star

Sea urchin

Sea cucumber

Complex Invertebrates -Arthropods

• crabs • hard skeleton on the outside (exoskeleton) provides strength and protection.

• bilateral symmetry• segmented bodies

with jointed legs• efficient nervous

sytem and good sensory systems

insects

spiders

crabs