The phylum's name is based on this feature (Arthropoda means "joint-foot" referring to the external joints in the skeleton that allow movement).
There are both advantages and disadvantages to an exoskeleton
The advantages seem to outweigh any disadvantages, judging from the phylum's success and diversityIntroduction
(though most have a second appendage called pedipalps)
Their body is divided into two main sections: an anterior cephalothorax and a posterior abdomen.
There are two main classes:
Their spawning time is the last two weeks in May and the first two weeks in June. They crowd up on the beach at high tide.
The anterior cephalothorax is covered with a horseshoe-shaped carapace, from which the animals derive their common name. Two large compound eyes and a pair of small simple eyes (at the anterior end of the median ridge) are on the dorsal carapace. The abdomen (posterior to the carapace) bears rows of short spines and a single large telson. Despite its formidable appearance, the telson is used neither for offense nor defense, and living animals can be safely handled.
I will help you if you ask!!!