Osmoregulatory and Excretory System

            Because of their diversity of form and life style, arthropods show considerable variety in many of their organs including the excretory system.  We will briefly examine two common arthropod excretory systems, which function in both osmoregulation and waste removal - green glands found in aquatic arthropods,  and Malpighian tubules found in terrestrial groups.

            Locate the green glands on the dissected crayfish. Despite their name, they appear pink and are located anterior to the stomach. They open to the exterior at the bases of the antenna (ventral surface).  The green glands consist of several parts, which will not be studied in this laboratory.  At this point, also locate the large mandibular muscles which operate the jaw-like mandibles.