Ciliates from the family Trachelocercidae (Karyorelictea) are commonly known as swan-necked ciliates. They are only found between the sand grains in marine sediment, and so they are rarely seen by casual observers. Here are two swan-neck ciliates swimming about while in conjugation.
Collected from Twin Cayes, Belize. Filmed on 2015-07-04.
[taxonomy:family=Trachelocercidae]