From my notes on the YouTube video I recorded in 2013:
A brood of very small rotifers, inside an empty test of Netzelia tuberculata. To get a closer look at them, I deliberately cracked the test and watched as one of them emerged and swam away. Ferry Siemensma was kind enough to send me drawings of a very similar rotifer, which he found in Difflugia capreolata in the early 70s. He has observed similar populations in many amoeboid tests, and strongly suspects that most are parasitic. He believes that this kind of parasitism is quite common, though seldom reported (perhaps because the opaque Difflugia tests hide the occupants). It is likely that the eggs are laid in a living arcellinid, which is then consumed from within.
Collected in Mer Bleue bog, mid May 2013.
Test 93 µm long
Olympus BHB 100X oil immersion (1000X)
