Invertebrates
Spineless Animals
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
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.
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
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
insects
 1 pair of antennae
 3 pairs of legs
 1-2 pairs of wings
 3 body sections
arachnids
 4-5 pairs of legs
 2 body sections
 fangs
centipedes/millipedes
 Centipedes have 1 pair of legs on each body section
 Millipedes have 2 pair of legs on each body section
crustaceans
 2 pair of antennae
 2-3 body sections
 They can chew
flatworm
 Flat bodies, head and a tail
 Most are harmless
 Some live inside the bodies of other animals
roundworms
 Thin bodies with pointed ends
 One way digestion system
 Most roundworms live inside the bodies of other animals
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