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