Home Page Scientific Methods Cell Structure Cell Function Microbes Plants Animals Biology Activities Biology4Kids Sections Search

Arthropods - Invertebrate Powerhouses

We'll start with the big numbers. About 75% of all animal species are arthropods. There may be more individual worms in the world, but there are more different types of arthropod than any other group on the plant. You'll find insects, spiders, crabs, lobsters, barnacles, centipedes, and even hundreds of extinct species in fossils.

Basic Structure Stuff

You know the first one. Arthropods all have exoskeletons. Exoskeletons are hard outer shells made of chitin. While you have an endoskeleton, a crab has a tough shell that protects it from the outside world. Next on the list are the arms and legs. They have jointed appendages. That's what the name arthropod means. jointed leg. Inside those joints and exoskeletons are muscles that help the organisms move.

Not all exoskeletons are the same. While they may all have chitin, a shell created by the epidermis, crustaceans have an extra layer that is calcified. That calcification makes it much sturdier and much heavier. Arthropods also have very advanced sense organs. You are probably familiar with the faceted eyes of flies and antennae on insects. Those are great examples of how arthropods are prepared to interact with the world. They also have open circulatory systems. These systems circulate nutrients throughout the inside of that exoskeleton so the muscles receive all the energy needed to move quickly.

Major Categories

There are four major types of arthropod. Three are found around you while one group is extinct. Trilobites are an extinct group that can be found in fossils around the world. Chelicerates include species such as spiders and horseshoe crabs. Uniramians include centipedes, millipedes and the biggest group of arthropods. Insects. Crustaceans are the last category of arthropod. Crustaceans include crabs and lobsters. They are mainly aquatic species.

Next Page on Invertebrates
- Overview
- Sponges
- Starfish - Urchins
- Anemone - Coral
- Jellyfish
- Cnidarian Structure
- Octopi - Squid
- Snails - Clams
- Flat Worms
- Round Worms
- Segmented Worms
> Arthropods
- Arthropod Structure
- Insects
- Crustaceans
- Spiders - Scorpions


Link to Link to Link to Link to Link to Link to Rader Network Side Navigation

Cicada Swarms (BBC Video)
- or -

Invertebrates Quiz

Arthropods Quiz

Useful Reference Materials (Arthropoda):
Encyclopædia Britannica:
Books on
- Modern Biology (Rinehart and Holt)
- Campbell Biology: Concepts and Connections (Reese, Taylor, Simon, and Dickey)
- Prentice Hall: Biology (Miller and Levine)
- Biology of the Invertebrates (Pechenik)
- Integrated Principles of Zoology (Hickman)

- Biology4Kids: Scientific Method
- Chem4Kids: Biochemistry
- Geography4Kids: Populations
- Geography4Kids: Food Chains
- Geography4Kids: Aquatic Biomes
- Geography4Kids: Land Biomes

Search for more information...

* The custom search only looks at Rader's sites.

Help Page Go for site help or a list of life science topics at the site map!
©copyright 1997-2015 Andrew Rader Studios, All rights reserved.
Current Page: | Invertebrates | Arthropods

** Andrew Rader Studios does not monitor or review the content available at external web sites. They are paid advertisements and neither partners nor recommended web sites. Specific links for books on are only suggested starting points for further research. Please browse, research options, and choose the appropriate materials for your needs.