How susceptible to ESD damage are JFET gates?
Because the gate-source voltage of (say) an N channel JFET is controlled from around 0 volts to anything down to -15 volts, a zener diode isn't normally needed to restrict positive ESD. This is because the gate-source region will act like a forward biased diode with positive levels on the gate and this will "normally" protect: -



If the gate is forward biased, because of the PN junction, it will conduct (just like the base on an NPN BJT conducts current to the emitter).

A MOSFET gate-source voltage does not have this "feature" built-in hence, if you need to supplement the protection because of potential ESD, you might consider back-to-back zener diodes.