Survival of five species of ciliates from the shipworm Nausitora hedleyi in sea water under the laboratory conditions were studied. The results indicate that Nucleocorbula adherens, Boveria teredinidi andi Trichodina balakrishnia are comparatively more adaptable to sea water than the other two si)ecies, Thigmozoon fencheli and Nyctotherus marina. The period of survival of the ciliates in healthy condition in sea water outside the body of the host in these tropical waters is short varying from 6 to 24 hours. This lime limit seems to be reasonably adequate for a significant number of these ciliates to be ingested along with the inhalent current of water and thus reach their habitat.