(full paper is archived in the Miller Library)
Title: The effects of temperature on the jet escape response of the squid Loligo opalescens
Student Author(s): Ripley, Beth
Faculty Advisor(s): Gilly, William
Location: Final Papers Biology 175H
Date: June 1997
Abstract: Loligo opalescens migrates vertically, experiencing large temperature changes in short amounts of time. Loligo depends on jet-propulsion for escape behavior, and at 12 degrees C shows an escape response that uses coordination between two motor systems employing giant and non-giant neural fibers. Little is known about escape behavior at colder temperatures, however, and experiments were done to determine how this behavior changed over the biologically relevant temperature range of 12 -4 degrees C. Squid were restrained and recordings of stellar nerve activity and intra-mantle pressure transients were taken during escape behavior elicited by strobe flash stimuli. As temperature decreased, pressure showed an increase in amplitude and duration, as well as an introduction of a plateau followed by a slower increase in amplitude below a critical transition temperature at 8 -10 degrees C. Neural recordings suggest that these findings may be due to both the introduction of two giant axon spikes at the transition temperature, as well as an increase in small fiber activity at lower temperatures. In free-swimming squid, these changes are manifested as a longer period of propulsive thrust which moves the squid a larger distance in a given time. These findings suggest that Loligo is able to maintain performance at colder temperatures through coordination of the giant and non-giant motor systems in a way that is similar to, yet distinct from, that at warmer temperatures.