1. Sponges do not have a digestive system, circulatory system, or nervous system. They do not have organs.
Sponges

2. Echinoderms are a group of marine invertebrates that includes:
Star fish
Sea lilies
Feather stars
Brittle stars
Sea cucumbers
Sea urchins
Echinoderm

3. There are about 6000 species of echinoderms alive today. 

4. "Echino" means spiny and "derm" means skin.
Echinoderm

5. Echinoderm Some echinoderms have tube feet.
If you ever turn a starfish over you will see hundreds of little tubes on each arm. Those tubes attach to an object, suck in, and attach to help the creature move.
Echinoderm

6. Echinoderm The sea cucumber Starfish tubefeet
Starfish tubefeet
Echinoderm

7. Cnidarians are a group of marine invertebrates that includes:
Corals
Hydras
Jellyfish
Sea anemones
Sea pens
Cnidarians

8. They are a group made up of around 9,000 species.
Cnidarians

9. They live in all ocean and some freshwater environments, however are most abundant and diverse in tropical waters.
Cnidarians

10. Cnidarians

11. Cnidarians Cnidarians are symmetrical, they all have a central axis.
They have no organs, only a mouth and digestive tract.
Cnidarians

12. Molluscs Molluscs are a group of invertebrates that include: Squid
Octopi
Cuttlefish
Snails
Slugs
Mussels, clams, oysters, and scallops
Molluscs

13. Scientists estimate that there are more than 100,000 species of molluscs today.

14. Molluscs

15. This makes them the second largest phylum of animals, having fewer species than only the arthropods.
Molluscs

16. Molluscs

17. Most mollusc species grow a hard shell for protection, but their shell grows in only one or two pieces; they don't have joints in their skeleton.
Molluscs

18. Molluscs

19. Molluscs There are three main groups of mollusks:
Snails ( Gastropods )
Clams, oysters, and mussels ( Bivalvia )
Squids and Octopi (Cephalopoda )
Molluscs

20. And then… I got hungry.

21. Molluscs

22. Molluscs

23. Molluscs

24. Molluscs

25. Molluscs

26. Molluscs

27. Molluscs

28. Molluscs

29. Molluscs

30. Molluscs

31. Molluscs

32. Pearls?
­The formation of a pearl begins when a foreign substance slips into the oyster between the mantle and the shell. It's kind of like the oyster getting a splinter. The oyster's natural reaction is to cover up that irritant to protect itself. The man­tle covers the irritant with layers of the same substance that is used to create the shell. This eventually forms a pearl.
Molluscs

33. Arthropods Arthropods are a group of invertebrates that include:
Insects
Spiders
Crabs and lobsters
Barnacles
Centipedes
Arthropods

34. Approximately 85% of all known animals in the world are part of this group.
Arthropods

35. Arthropods have jointed appendages
Arthropods have jointed appendages. The name arthropod means: jointed leg.
Arthropods

36. Inside those joints and exoskeletons are muscles that help the organisms move.
Arthropods

37. And then I got hungry again…

38. Annelids Annelids are a group of invertebrates that include:
Earthworms
Ragworms
Leeches
Annelids

39. Annelids (segmented worms) are a group of invertebrates that includes about 12,000 species

40. Segmented worms are bilaterally symmetrical.
Annelids

41. Their body consists of a head region, a tail region and a middle region of numerous repeated segments. Each segment contains a complete set of organs.
Annelids

42. Most segmented worms burrow in terrestrial soils or sediments at the bottom of freshwater or marine waters.
Annelids

43. Invertebrates

44. Invertebrates

45. Invertebrates

46. Invertebrates

47. Invertebrates

48. Invertebrates

49. Diplocardia longa
Bioluminescence

50. Arachnocampa luminosa
Bioluminecense

51. Bioluminescence

52. Bioluminescence