Morphology of Stage II Larval Mouthparts of the American Lobster, Homarus americanus: First and Second Maxillae

Abstract

Homarus americanus, commonly known as the American lobster, is a highly complex crustacean that undergoes a series of developmental phases prior to adulthood. Homarus americanus bears six, layered sets of segmental appendages that serve as mouthparts for feeding"“ the mandibles, first maxillae, second maxillae, and first, second, and third maxillipeds. These appendages themselves also face anatomical and physiological changes throughout larval development. All mouthparts bear setae, which are hair-like projections that provide both mechanical and sensory functions (Lavalli and Factor, 1992). The types of setae found on the different mouthparts of the lobster have been divided into 12 distinct categories. These setae also consist of setules along its surface. Both structures aid in feeding for Homarus americanus.

This study focuses on the morphology of the first maxillae of the second larval stage of Homarus americanus. This particular mouthpart is thoroughly examined by means of light microscopy and scanning electron microscopy.