Meeting Abstract
P1.99 Monday, Jan. 4 The Functional Morphology and Transmitter Distribution an Olfactory Organ of Tritonia diomedea CAIN, S. D.*; CLARK, M.; KELLY, D.; Eastern Oregon University; Eastern Oregon University; Eastern Oregon University shaun.cain@eou.edu
The sea slug Tritonia diomedea has become a model for investigating the neural mechanisms that underlie orientation and navigation behavior. Previous research has shown that this epibenthic marine organism uses a combination of at least three primary sensory modalities (mechanoreception, magnetoreception, and chemoreception) to explore and navigate through its environment. Both magnetoreception and mechanoreception appear to provide the animal with direct directional information that serves to guide the animal in an appropriate direction. Olfaction, on the other hand, appears to serve as a motivational cue that initiates different types of behavior, including rheotaxis. For example, a sea pen (the primary prey of this sea slug) upstream of the slug initiates positive rheotaxis, whereas a predator (Pycnopodia helianthoides) elicits a swim escape response. One of the primary organs mediating chemoreception is the lateral tip of the animal’s oral veil. Here we report the functional morphology of the lateral tip as it relates to chemoreception. The tip forms a densely ciliated channel on the ventral surface that drives a current of water up from the substrate to the base of the tip. These cilia are controlled by at least two different and widely distributed neurotransmitters, the neuropeptide TPep and 5HT. In addition, an opening on the tip leads to a cylinder that runs the entire length of the tip and contains large cilia-like structures, the function of which is unknown. Video recordings of the behavior of the lateral tip, coupled with previous research, imply that the organ functions much like a nose and that the cilia, controlled by centrally released neurotransmitters, can increase or decrease the amount of chemosensory information entering the CNS by changing beat frequency.
