1. Invertebrates These are animal without a backbone
Most animals in the world are invertebrates
These are animal without a backbone

2. Groups The most common groups of Invertebrates are: Arthropods
Protozoa
Annelids
Echinoderms
Mollusks
Many invertebrates have a fluid filled skeleton, like
a worm or a jellyfish.
Others have a hard outer shell like crustaceans (crabs)
and insects (spiders).

3. Arthropods
Arthropods include:
Insects
Arachnids
Crustaceans

4. Arthropods: Insects Insects are the largest group of arthropods.
They are very adaptable which means they can live almost
anywhere in the world.
They have an exoskeleton which serves mainly as a protective
covering.
An insects body consists of 3 parts: head, thorax and abdomen

5. Arthropods: Insects More characteristics of insects: pair of antennae
compound eyes
have legs
some have wings
Compound eyes in the head of a crane fly

6. Arachnids Characteristics: spiders, scorpions, ticks and mites
do NOT have antennae
exoskeleton
have many legs
scorpions are the largest arachnid group
spider scorpion tick mites

7. Crustaceans Characteristics:
Most common are the crab, lobster and barnacle
Live mostly in the ocean or other waters
Have a hard, external shell that protects their body
Have a head and abdomen
Their head has antennae
Have legs
Some have claws
crab lobster barnacle

8. Protozoa Protozoa are single celled animals
Most are extremely tiny (microscopic)
consume(eat) bacteria
Two main types: amoebas, flagellates
flagellate
amoeba

9. Annelids Annelids have bodies that are divided into segments (parts).
They have bristles (like legs). Some have short ones (earthworms)
others have long ones.
They have very well-developed internal organs, so it’s easy
for them to move around on the ground.
There are about 9,000 of known annelids.
lugworms, clam worms, bristle worms, fire worms, sea mice

10. Echinoderms These animals live in the ocean
They have arms or spines that start at the center of their body
The center part of their body contains their organs and their
mouth
The spines often protect them from predators
Examples are: star fish (sea stars), sea urchins, sea cucumbers
Sea stars
Sea cucumber
Sea urchin

11. Mollusks Most mollusks have a soft sin-like organ on the inside and
a hard shell on the outside
Some mollusks live on land and others in the water
Examples of mollusks that live on land:
snails and slugs
Examples of mollusks that live in the water:
oyster, mussel, clam, squid, octopus
oyster mussel clam squid octopus

12. Mollusks Land mollusks have a soft “foot” that helps them move—but
they move very slowly
Water mollusks propel themselves in the water by ejecting
water from their bodies
Some mollusks, like the oyster, attach themselves to rocks and
Feed from the food particles