[color=ed1c24][b]"I am familiar with the aquatic variety."[/b][/color]

So, in short.  Yes, he DID know what it was he was dealing with in these things.  In truth, Zen was not sure if the desert Serris and the water Serris were not all one species that could live in both environments, but that was irrelevent to the whole situation.  Kathrin was concerned over whether he knew what he was doing, and the answer was yes.  The pulse shots were preventing the creatures from performing an outright charge directly for the group, disrupting the direction of their potentially super-fast motions.  In this case, the seismic impact to the ground with his pulse shots were jarring to the senses.  X-made creatures or not, they were disrupted via this action.

The gun and flame support of the others did help to a degree.  It confused the creatures.  Every time they received input that they could not understand, the creatures became more and more confused as to their surroundings.  They could not see underneath the dirt.  However, if the perimeter guns had failed, it meant that something had happened here.  While there were arguments as to how to handle the situation, Zen piped into all their communications at once.

[b][color=ed1c24]"This is a controlled suppression maneuver to fallback from hostiles in an organized manner."[/color][/b]

There was a sudden explosion of dirt and dust as a Serris had looped back for a charge at high speed and leapt out of the ground right for Zen!  The android's eye beams lit up and focus-fired on it to make it fall back so it had to squirm back uunder the dirt.  Anyone who wanted to open fire on it were welcome to.  It's worth noting that any bits of matter that had burnt off intact from the critter was starting to liquify and pulse into something small and amoeboid.

[b][color=ed1c24]"It is required that you move quickly, as I am the primary suppression unit and can match their speed.  Estimated time to attempting a group attack, 30 seconds.  Estimated time to more creatures appearing, unknown.  Begin moving, NOW."[/color][/b]

Zen just activated his engines, and was slowly guiding himself back.

Incidentally, for anyone who IS moving back to the bunker, it ALSO looked like the one from [i]Screamers[/i], with a big armored hangar door...that was torn open...by something larger than Serris.  Anyone looking inside, though, would find that the emergency blast doors were okay.  They just...never got to activate them.  What happened here?