also receive sensory input from the sensitive hairs on the tail fan. Each ganglion contains the body of one motor giant neuron (MoG), powerful and large bodied motor neurons whose projections innervate the five fast flexor (FF) muscles found in a segment and interact with them through chemical synapses. The ganglia also contain two sets of giant axons known as the lateral giant neurons and the medial giant neurons. These interneurons play important roles in escape swimming. Their large diameter allows for rapid conduction since there is less current leakage. Their projections extend through the third root in each ganglion, and Furshpan and Potter found that the synapses they subsequently made with the MoG passed depolarizing currents in a direct and unidirectional manner. These electrical synapses account for the speed of the escape mechanism and display some features of chemical synapses such as LTP and LTD. Variations in escape response characteristic depend on the location where the crayfish body is prodded or attacked and also depend on which of the giant neurons is stimulated. Response variants and their circuitry Medial giant-mediated escape The medial giants innervate the entire ventral nerve chord. Their cell bodies and dendrites begin in the brain and collect sensory information presented by visual and tactile stimuli. These fibers terminate in the last abdominal segment. The response is triggered by abrupt tactile stimuli to the head or alarming visual stimuli. This results in the firing of all motor giant (MoG) neurons and the flexion of all the phasic fast flexor (FF) muscles in the abdomen, which rapidly curls the tail fan and last three segments underneath the crayfish. This produces a thrust that directs water towards the offending stimulus while propelling the crayfish directly backward. This behavior is then followed by the extension of the tail, which prepares it for swimming or the execution of another tail-flip. The extension and swimming phases will be discussed in the next escape variant. Unfortunately, this variant of the tail-flip escape has not been extensively studied. Further studies should focus on this escape variant, paying special attention to exactly how visual information is processed and then converted into neuronal signals that produce a tail flip response. Non-giant escape Less abrupt or gradually intensifying stimuli evoke locomotion behavior similar to that seen in giant interneuron-mediated behaviors. However, the movements are less stereotyped and do not appear to occur in an all or