Which low voltage single supply opamp for ultrasound mic?
The microphone's output impedance is irrelevant to the choice of op-amp, because you "program" that aspect by a suitable op-amp circuit.

The low impedance of the mic means that the amplifier can have a low input impedance, in the thousands of ohms. But if the connection from the mic to the amplifier is short (we don't have to worry about stray capacitance of a cable), it doesn't have to. You can build the amplifier to have a relatively high input impedance, like 50 kOhms and up.

If you plan on using a coupling capacitor, like in the recommended circuit, a low input impedance will work against you: a low R means you will need a large C to maintain frequency response, which is linked to the RC product.  (Since you give the audible range as 10 Hz (!) to 20 kHz, it can be assumed that you care about low frequency response).

The choice of op-amp depends on various parameters. This is a shopping question that is generally considered off-topic (on most stackexchange sites). You probably want it to be a low-noise unit suitable for audio, which has published distortion figures which are low. Then you have to consider your power supply: would a dual op-amp IC that drains up to 16 mA of current be acceptable? Or how about one that needs a minimum of 10V across its power rails to work properly: would that work? Cost: is it okay if the op-amp costs ten dollars? Or is fifty cents more appropriate? Output: does the op-amp have to produce output that goes almost all the way to the power rails? Or is it okay if it only goes to within a few volts of either rail before clipping? Manufacturing: are you comfortable with small, surface-mounted IC's, or would it be better to have a classic through-hole part with 0.1" pin spacing?

Whether or not a voltage divider is the best approach to power the mic depends on how much wattage will be wasted, and whether you can afford it.