Notes an arthropods

Here are some general things to know about arthropods for those who were gone today…

1) arthos – jointed and pod – foot; so arthropod means jointed foot (or appendage)

2) arthropods have body segments: in the past they had many, now the have 2-3 with the exception of mili or centipedes. 3 = head, thorax and abdomen; 2 = cethlothorax and abdomen.

3) arthropods have exoskeletons – external skeletons for support and movement. These don’t grow and must be molted in order for the organism to grow.  When they molt they are vulnerable due to the soft shell and they puff themselves up so their new exoskeleton allows room to grow.

4) arthropods go through metamorphosis. Complete metamorphosis means the larva look completely different from the adults and has the stages egg -> larva -> pupa -> adult. Incomplete metamorphosis means the young (nymphs) look like the adults but don’t have developed sex organs and has the stages egg -> nymph -> adult.