Invertebrates Spineless Animals Sponges Sponge is the simplest

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