sec8^KG02723 mutants hatch at the normal time and initially appear normal in size and behaviour. Although these mutants survive through larval stages, they fail to eclose. During the first larval instar stage, NMJ morphology appears normal in sec8^KG02723 mutants. However, in the third larval instar stage, muscle 6/7 NMJs show changes in morphology and terminal number compared to wild type. With lower penetrance, sec8^KG02723 NMJs show abnormal neurite growth and significantly increased numbers of presynaptic boutons and branches. However, these mutants present no obvious defects in body wall muscle shape or size. The amplitude of spontaneous synaptic currents is significantly reduced in sec8^KG02723 mutants compared to wild type. The cluster size of both A- and B-type glutamate receptors is significantly reduced in sec8^KG02723 larvae. Synaptic microtubule density is significantly increased in sec8^KG02723 larvae.