Chapter 31 - Protostome Animals - 31.1 - Protostomes Account for More Than Half of All Described Species - 31.1 Recap - Learning Outcomes - Page 662: 1

Animals with an exoskeleton are offered protection that can be carried around wherever the organism goes. However, the chitinous shell cannot grow with the body, so the animal must perform ecdysis during growth. Marine arthropods have gills that filter oxygen, and terrestrial arthropods have tunes called tracheae that open up to spiracles on the body's surface.

Animals with an exoskeleton are offered protection that can be carried around wherever the organism goes. However, the chitinous shell cannot grow with the body, so the animal must perform ecdysis during growth. Marine arthropods have gills that filter oxygen, and terrestrial arthropods have tunes called tracheae that open up to spiracles on the body's surface.