green crab Arthropoda is the largest of all the phylums. It also shows the greatest diversity. Common characteristics of this phylum include molting and regeneration. They also have a hard chitinous exoskeleton and joined appendages. The body plan of these animals consists of the thorax, head and abdomen. Arthropoda stand out from other phylums because of their well developed pair of antennae sensory organs and eyes.
Crabs (including Hermit Crabs), Lobsters, Barnacles, Shrimp, Amphpods and Isopods all belong to the same Arthropoda familly. The Green Crabs pictured above are slightly smaller then the other crab types found in intertidal and subtidal zones. You can tell them apart because the Green Crab is unique in having five "teeth" (for g-r-e-e-n) in the front of its carapace. These crabs are extremely common, scavenging under most middle zone rocks. The crabs are green on top, males having yellow undersides, and females being redish-orange. The abdomen of the females is also wider then the males, used for carrying eggs after being fertilized.

The Amphipod pictured bottom, right is a small olve-green shrimp-like crustacean found under rocks and seaweed. Amphipods are scavengers eating small organic debris. Known to some as scuds or sideswimmers these animals are laterraly composed with small eyes, small head, and strongly arched back. Ampipods are often seen in swarms with larger males clutching smaller females.


Barnacles (above) will probably be the most common thing you will see. They are found on rocks in all intertidal zones. These small, shrimp-like crustaceans cement their heads to rocks while building a limestone house around their bodies. These strange creatures even eat with their feet! When under water Barnacles open their movable top plates and extend their legs to filter plankton. These Mollusks are also hermaphroditic and cross-fertilize each other.

So have you been woundering about their eating habits? Now you can see a Movie of How Barnacles Eat!
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