Eliminations

How a process of elimination identified the zoo keepers (see recent posts and here):

Eliminated
The gorilloids (tested with a specially devised instrument):
color blind;
unable to focus on the ship's instruments;
brain small;
most brain activity controlling animal functions;
canine intelligence level.

The lone elephantoid (this and the rest considered logically):
too big;
one individual not enough to pilot and land the ship, then collect and care for specimens etc.

The tiger apes:
reverting to quadrupedalism;
not specialized enough.

The caterpiggles:
the emergency acceleration switch fell too easily, thus not suitable in high gravity;
such light shelves would not be built in high gravity.

The tentacle centaurs...
...breathe hydrogen, therefore would not use copper oxide rectifiers exposed to their atmosphere.

The helmet beasts:
too small and slow;
not enough room for real brains.

Solution
The cabins have big and small cubbyholes. A zoo keeper is a helmet beast symbiotically attached to a gorilloid. Flandry informs us that the planet of the Togru-Kon-Tanakh came to be named "Vanrijn."