1. Characteristics of Arthropods Kinds of Arthropods

2. Four Main Characteristics
Segmented body with specialized parts:
Head: foremost part of a crayfish.
Thorax: upper part of a crayfish's body
Abdomen: lower part of a crayfish's body.

3. Jointed Limbs
Jointed limbs give arthropods their name. Arthro = joint, and Pod = foot.
Jointed limbs are legs or other body parts that bend at the joints

4. External Skeleton
Arthropods have a hard outer covering that is called an exoskeleton.
An exoskeleton does the some of the same functions as an internal skeleton. Supports the body.
Also, the exoskeleton has functions unlike an internal skeleton: acts like a suit of armor protecting organs inside the body, keeps water inside the animal’s body so it can survive on land without drying out.

5. Sensing Surroundings
All arthropods have a head and well developed brain.
Their brain receives information from many sense organs, including eyes, bristles and antennae.
Some arthropods have a compound eye: that is made up of many identical, light-sensitive units, for example the fly.

6. Kinds of Arthropods Centipedes and Millipedes Crustaceans: crayfish
Arachnids: spiders, scorpion, mites and ticks.
Insects

7. Echinoderms Echinoderm = spiny skinned.
The spines are on the animal’s skeleton or endoskeleton (internal skeleton).

8. The Nervous System
All echinoderms have a simple nervous system. Around the mouth is a circle of nerve fibers called the nerve ring.

9. Water Vascular System
A system of canals filled with fluid. It uses water pumps to help the animal to move, eat breath, and sense its environment.

10. Types of Echinoderms Brittle Stars and Basket Stars
Sea Urchins and Sand Dollars
Sea Lillies and Feather Stars
Sea Cucumbers