Microanatomy of larval mouthparts and sensilla Larval and Postlarval Mouthparts of the American Lobster, Homarus americanus: Stage III First Maxillae and Stage IV Third Maxillipeds

Abstract

Homarus americanus, better known as the American Lobster, goes through several life-history phases before becoming an adult, including: three planktonic larval stages (stages I-III), a postlarval phase (the planktonic postlarval stage IV) and the settling postlarval stages IV-V, followed by juvenile and adult phases (Factor, 1995). The American Lobster has six pairs of mouthparts: mandibles, first and second maxillae, and first, second, and third maxillipeds. Each pair of mouthparts is unique (Lavalli and Factor, 1995). They vary in size, shape, type, and distribution of setae. Setae are hair-like structures, extensions of the cuticle, that are present on the mouthparts (Lavalli and Factor, 1995). This study focuses on the third maxillipeds from the stage IV postlarval stage of the American Lobster. Understanding the microanatomy of this mouthpart is important as it allows comparisons with the third maxillipeds from other developmental stages in the lobster's life history as well as help in understanding the passive feeding mechanism that these early stages may have.