CARBON DIOXIDE FROM THE NERVE CORD OF THE LOBSTER

Area of Science:

• Marine Biology
• Neurophysiology
• Crustacean Research

Background:

• The nerve cord of the lobster (Homarus americanus) is a delicate biological preparation.
• Its viability as a research subject is limited to a few hours post-excision.

Purpose of the Study:

• To investigate the physiological changes in the lobster nerve cord after removal from the organism.
• To quantify the carbon dioxide (CO2) discharge rate and its response to stimuli.

Main Methods:

• Measurement of CO2 output from isolated lobster nerve cords over time.
• Comparison of CO2 discharge rates between quiescent and stimulated nerve cords.
• Observation of the effects of physical manipulation (handling, cutting) on CO2 output.

Main Results:

• Isolated lobster nerve cords exhibit a decreasing rate of CO2 discharge, starting at approximately 0.20 mg CO2/g/min and declining to 0.07 mg CO2/g/min within hours.
• CO2 discharge shows a steady decrease, unlike the 'gush' and 'uniform outflow' patterns seen in dogfish lateral-line nerves.
• Handling and cutting the nerve cord transiently elevate CO2 output.
• Stimulated lobster nerve cords show a 26% higher CO2 discharge rate compared to quiescent cords, a proportionally larger increase than observed in dogfish.

Conclusions:

• The lobster nerve cord's CO2 discharge is a transient physiological process that ceases with tissue death.
• Nerve cord excitability, indicated by increased CO2 output upon stimulation, is measurable in vitro.
• Comparative physiology reveals differences in nerve tissue response between crustaceans and fish.