No you don't have to worry at all about them surviving
"too well".

Wayne Sallee
Wayne's Pets



John - D wrote on 6/1/2006 12:40 PM:
Thanks everyone for the reply.

I have identified the crabs as Phimochirus Holthuisi.

I believe I already have two of these types of crabs in the tank (the
tank was purchased stocked second hand) ... but I am doing this from
memory so I may be a little off. My biggest concern was not that the
barnicles would survive .. but that they would survive "too" well and
become an nuisance such as glass anenomies.

Thanks again for your help!

John D.

Tidepool Geek wrote:
Hi John,

Like the hermits you collected, those hitchhiking barnacles are marine
animals. If you collected them in the intertidal zone it's probably
safe to assume that both are also pretty hardy with regard to
temperature and salinity.

That said, you still have a number of issues and unknowns to consider:

1. Temperature - Even tidepool animals are best kept at or near the
temp of their natural habitat. Do you know what temp these guys are
used to?
2. Exposure - Some intertidal animals NEED to be out of the water for a
while each day. You need to think about how far up the beach your crabs
were when you collected them. This one is probably not a problem; most,
but not all, hermits are best off underwater at all times. You can also
assume that the barnacles will be OK anywhere the hermit is - otherwise
it wouldn't have settled there in the first place.
3. Replacement homes - Keep in mind that hermits need an ongoing supply
of empty snail shells.
4. Food (part one) - Crabs are opportunistic feeders and can, depending
on species, become a problem in an aquarium because they sometimes
decide to eat things that you don't want eaten. OTOH: Some crabs seem
to be 'good citizens' and only eat detritus and leftovers. You need to
get some idea of what your crabs are likely to do. For that, you need
to pin down what species you have. Keep in mind that there are a LOT of
different species of hermit and that each species will have somewhat
different preferences.
5. Food (part two) - Barnacles are filter feeders. I don't know if they
specialize on phytoplankton or zooplankton but I suspect that it, like
so many things, depends on species. In general, home aquariums don't
generate enough plankton to sustain filter feeders and must have
plankton added. [Lots of people do just this and there are several
plankton products on the market.]
6. The 'so what' factor - The barnacle(s) will probably die due to lack
of food or some other problem but that's not such a big deal. Barnacles
are usually small (although we have one in my neighborhood that can
reach 4 inches across) and are close to 75% inert shell matter. A dead
barnacle or two shouldn't be a problem for your water quality.
Ethically, a barnacle in the wild doesn't have a one in a million
chance of making it to maturity; even one that makes it to the sessile
stage of life faces 1000+ to 1 odds against living to reproduce.

IMHO: Collecting animals locally is only appropriate if you have done a
good deal of homework about the target species first. Even in Florida
anything collected on a whim for a tropical home aquarium is far more
likely to go wrong than right.

Cautionarily yours,

Alex