BTA and NEMS in general

[Massengill]

Why is it that BTA can survive something so drastic as being cut in half with scissors, but die so easily in an aquarium. I watched a video on YouTube the other day of a guy "how to frag a NEM", it looked so horrible, but the two halves survived. It looks like this guy does it all the time. He'll buy a big BTA then split it so he will have two BTA for the price of one. I have also seen before and after videos from other people who do the same. It looks like the NEMS recover well, but it's still hard to believe even after seeing it with my own eyes. I lost a BTA that got stuck up against a heater, and another that got it's foot sucked into a powerhead, and lost a LTA to a bristleworm, but these BTA are surviving being cut in half? Is this common practice in the hobby?

 

[garygb]

For BTA's the success rate is very high for fragging. For some species, fragging success seems to be (or approach) zero. This may have to do with the fact that BTA's divide naturally. Some species are believed never to assexually reproduce and only propagate through sexual reproduction.

You asked how an anemone can be cut in half and survive, but die so easily in an aquarium. I think that has to do with the fact that in the wild they are not exposed to poor water quality--not for any length of time at least. In the open ocean the water is consistently as good or better than in our tanks on a good day. Anemones have evolved to regenerate after being damaged by predators, but the host anemones haven't ever had to handle poor water quality. There are species of anemone that come from areas where the water quality isn't so great and they can handle poor water quality.

BTW, I would question whether bristleworms killed your LTA. Bristleworms move in when an animal is in the process of dying. I think you LTA was on its way out and the bristleworms were just moving in to clean up.

 

[Massengill]

My LTA was about 8" in diameter with 2-3" long tentacles and a nice dark brown one day and ate once a week, then the next day he was shriveled up, the next day it was about the size of a ping pong ball and tumbling around in the tank. I scooped it up to examine it to find two or three small holes in its base, and it's innards exposed from it's foot and mouth. So tell me what happened then? Healthy as a horse, then BAM . . . down the toilet the next. I left it in the tank another day or so to observe. Then it started to wither away, so I removed it. It was under great lighting, good water quality running a skimmer, hosted my Skunk clown, etc. I had it for a few months, and it appeared very healthy when I got it, not bleached, foot attached, good mouth etc.

 

[garygb]

Hard to say what caused its demise, but all that I have read regarding bristleworms (the small ones that most all of us have in our tanks, not the giant ones that some people get) are harmless and only move in when an animal is on its way out.

 

[ssavader]

Animals that have "radial symmetry", such as BTAs, starfish, jellyfish have a unique shape that allows for "duplication" of the central nervous system, regardless of how simple. Radial symmetry also allows for "centralization" of the gut system, so division does not deprive each part of either a CNS or digestive tract. Since "respiration" and "circulation" are supported by diffusion as opposed to an active system (like higher animals have), division does not result in these animals bleeding to death or dying of respiratory failure. So, many of these animals can survive being divided, and as garygb said, is further supported by their reproductive method of divsion. However, a "burn" from a heater places the whole organism at risk of dying because the traumatized portion of the animal "drains" all the resources of the whole organism, leading to "multi-system failure" and death (like an Intensive Care patient dying from a simple infection- the infection drags down the entire organism [patient]).