The structure and function of the labrum in the lobster Homarus gammarus (L.)

Area of Science:

• Marine Biology
• Crustacean Anatomy
• Functional Morphology

Background:

• The labrum is a poorly understood crustacean feeding appendage.
• Its role in ingestion requires detailed anatomical and physiological investigation.

Purpose of the Study:

• To describe the labral skeleton, musculature, and innervation in Homarus gammarus.
• To investigate the functional role of the labrum during feeding behaviors.

Main Methods:

• Anatomical dissection and histological examination of the labrum.
• Electrophysiological recordings from the inner labral nerve.
• Observation of feeding behavior and associated labral movements.

Main Results:

• Detailed description of the labral skeletal elements, muscle attachments, and three bilateral sensory neuron groups.
• Identification of phasic afferent activity in the inner labral nerve upon mechanical stimulation.
• Rhythmical retraction-protraction movements of the labrum during ingestion, coordinated with mandibular and esophageal activity.

Conclusions:

• The labrum of Homarus gammarus possesses a complex sensory innervation and active musculature.
• Labral movements are integral to the crustacean feeding process, particularly during ingestion and swallowing.
• Further research into labral function can elucidate decapod feeding mechanics.