If you're talking about any old tube worm, and with respect to the strict flood-geology, young-earth creationism Ken Hamm insists on, then this is indeed puzzling. Ken wants the flood to have created most of the earth's fossiliferous geology, and mostly in the space of one year. Think of all that strata held in suspension in the world ocean. It must have been a thick, hot slurry of rock, mud and minerals. The problem goes well beyond filter feeders requiring clean water. How did anything survive? Obviously there must have been aquaria on the ark, and Noah sealed the huge plexiglas plates with the same pitch he used on the "gopher wood" of the ark itself. (See, that was easy!)
If you have in mind the tube worms living in the deep ocean trenches, it used to be the case that the ICR brand of flood-geology included, if somewhat peripherally, the notion that the pre-flood earth had more-or-less uniformly shallow oceans (thus no deep thermal vents). The relief of the land was considered similarly subdued (thus few or no alpine environments).
Actually this was but a fancy of Henry Morris, included in The Genesis Flood co-authored with John C. Whitcomb, Jr. in 1961. Back in the day Morris' fancies had a way of becoming rock-ribbed doctrine. Morris was quite the doctrinal enforcer. I haven't followed the Institute for Creation Research closely enough in recent years to determine if his son has the same talent and inclination.
Another notion, which I think might have originated with Morris or Whitcomb, was that continental drift just started happening one day, after the flood (indeed not long after that whole Babel thing IIRC). Morris and Whitcomb wrote their breakthrough tome at a time when plate tectonics was still aborning, and quote-mined the early critics to dismiss the theory. The YECs later decided that maybe they did need to shove some continents around, and latched onto a couple of passing biblical reference to Peleg (son of Eber, father or Reu) "in [whose] time the earth was divided".
That may seem a thin biblical reed upon which to set continents skittering around the globe (they've slowed to their current rate of centimeters per year, you see) but then as Morris tells us in TGF, on the page I just happened to open my copy to, "the instructed Christian knows that the evidences for full divine inspiration of Scripture are far weightier than the evidences for any fact of science." Walter Brown still advocates this historical hyper continental drift today.
Anyway I must admit to being at a loss as to how the thermal vent communities got transplanted from Noah's aquaria to the deep ocean trenches. Maybe, while the rest of the biblical folk where messing around with that big tower, Peleg got himself some pitch and some gopher wood and made a submersible?