1. Spineless Animals
Invertebrates

2. Sponges
 Sponge is the simplest kind
of an invertebrate.
 Shaped like a sack with an
opening at the top
 It’s body is made of 2 cell
layers
 Body is hollow inside
 Live in water
 Adults stay in one place, their
kids float around

3. Mollusks
 Mollusks are an invertebrate that has a soft body and a
shell
 Most live in water, snails and slugs live on land
 Some stay in one place, others float.
 Shells are sometimes inside their bodies.

4. Cnidarian
 A cnidarians (nye-DAYR-ee-uhn) is an animal
with arm like parts called tentacles.
 Sting their prey with stinging tentacles
 Some stay in one place, others float around

5. arthropods
 Arthropods have jointed legs and a body that is
divided into sections.
 Largest group of invertebrate
 Have exoskeleton, hard cover protects the body
 4 major groups: insects, arachnids, crustaceans,
centipedes/millipedes

6. insects
 1 pair of antennae
 3 pairs of legs
 1-2 pairs of wings
 3 body sections

7. arachnids
 4-5 pairs of legs
 2 body sections
 fangs

8. centipedes/millipedes
 Centipedes have 1 pair of legs on each body
section
 Millipedes have 2 pair of legs on each body
section

9. crustaceans
 2 pair of antennae
 2-3 body sections
 They can chew

10. flatworm
 Flat bodies, head and a tail
 Most are harmless
 Some live inside the bodies of other animals

11. roundworms
 Thin bodies with pointed ends
 One way digestion system
 Most roundworms live inside the bodies of other
animals

12. Segmented worms
 Bodies have 3 layers and divided into segments
 Have a head and tail- both have an opening to the
digestion system
 Only live on land- none live inside an animal’s body