It may have adapted so it wouldn't get eaten and so it could escape the predators <span />
Neurotransmitters are the chemical molecules, which help in transfer of the signals from one neuron to another. Inside the neurons, the signals are transferred as electrical signals, but at junction of two neuron, which is known as synapse, the signals are transferred in chemical forms.
These neurotransmitters have a definite shape and are recognized by the receptors present in the receptor site of the succeeding neuron. The neurotransmitters from the synapse binds to the receptor site of the receiving neuron. binding of the neurotransmitter to the receptor causes excitation of the receiving neuron, which also known as postsynaptic neuron.
Hence, Like a key in a lock, the shape of the neurotransmitter must bind with the receptors of the receiving neuron.
Absence of oxygen
fermentation is an anaerobic (meaning doesn't require oxygen) process