Crustaceans are the most dominant aquatic arthropods, since the total number of marine crustacean species stands at 67,000, but there are also freshwater and terrestrial crustacean species. Krill, shrimp, lobsters, crabs, and crayfish are examples of crustaceans (Figure). Terrestrial species like the woodlice (Armadillidium spp.) (also called pill bugs, rolly pollies, potato bugs, or isopods) are also crustaceans, although the number of non-aquatic species in this subphylum is relatively low.

Crustaceans have two distinct body sections, a cephalothorax and an abdomen, one pair of appendages per segment, two pairs of antennae, exoskeleton, and a carapace.

Figure 1. The (a) crab and (b) shrimp krill are both crustaceans. (credit a: modification of work by William Warby; credit b: modification of work by Jon Sullivan)

Complete the tasks on the list below:

Go to this page, http://cnx.org/contents/GFy_h8cu@10.53:OUA71yUo@7/Superphylum-Ecdysozoa, and read the about the following section(s):

Subphylum Crustacea

Use the Glossary at the bottom of the page to help with the vocabulary for this week
Use the Review Questions and Free Response questions to check for understanding
Watch the YouTube video, Armed and Armored: The Amazing Evolutionary Story of Crustaceans
Watch the animation Characteristics of Crustaceans

Download for free at http://cnx.org/contents/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.53