Rather than reply to any specific posts I decided to just write a general one. I really wish I would have seen this one back in August! While my current research is in arthropods, I have a long-standing love in annelids. I thought a basic background addressing certain points would be useful. Yaro's original point still stands uncontested.
The first thing to keep in mind with 'worms' is that the term defines an organizational grade rather than a taxonomic grouping. There are 'worms' across several phyla (Platyhelminthes, Nematoda, Nemertea, Annelida, Echiura, Hemichordata, etc.). The worms being discussed are annelid worms in the Class (probably polyphyletic) Clitellata. The other members of the phyum are Pogonophora (like the deep-sea vent tube worms of fame) and Polychaeta (the mostly marine bristle worms).
Sometime far back in this discussion the suggestion was made that earthworms living in lake sediments represented the same 'kind' as earthworms. For this to be true the definition of 'kind' needs to be once again stretched to impossible limits. Because those lake worms (Limnodrilus, I believe?) look like earthworms they must be the same kind. The fact is that Limnodrilus is in a completely different suborder (Tubificina) than is the earthworm (Lumbricina). If they are the same kind and diverged since the flood by microevolution then Humans and Lemurs could have microevolved since the flood (Suborder Anthropoida vs Prosimia), cows and pigs (I don't remember the taxa, Boviina and Suiformes? I am an invert guy!) and so on. The worms differ at a very important level. In another post marine blood worms were mentioned, these are actually a completely different class, Polychaeta. The polychaete called a blood worm is a glycerid, usually genera Glycera, Hemipoda, etc. The family is completely marine.
One of the more energetically demanding aspects of physiology is ion regulation. Most organisms, especially aquatic ones, simply cannot do it efficiently. The majority of marine invertebrates die quickly with even slight changes in salinity. Skin-breathing terrestrial organisms cannot usually tolerate any salt water. Freshwater creatures dehydrate in the presence of salt water. Yes there are a few creatures that are euryhaline but most (I would say 99% as a ballpark) cannot. So unless the flood maintained the exact salinity at the exact points all over the world, we would have lost both fresh and saltwater organisms. I cannot see how the flood could be both salt and fresh in all of the right places, makes no sense.
I do agree with Southerngurl's point (although not the flood) that earthworms wouldn't really have been a problem on the ark. The other thousands of kinds of worms would have been more problemmatic.