The genus of the protozoa were (in my opinion) Zoothamnium - attached to the tail (pleon) of the animal.
The "taxi" was a Cumacea. Cumacea (cfr. http://en.wikipedia.org/wiki/Cumacea ) are small marine crustaceans (between 1 and 10 mm long - in my case circa 4 mm). Many of them have a diurnal cycle: during daytime they are in the benthos and during nighttime in in the plancton. I found them in night-time.
Franz
