How do you tell the difference???

[Good Alex]

i have a mixed reef that has been running for about 3 years, and after doing much research on tridacnid clams, i decided to get one, after searching i picked a nicely colored deresa clam, that i made sure was not gaping and was opening up nicely, around 3-4in. but after about a week or so i came home and the clam had been cleaned out, no mantle, threads or foot, the shell was stripped, i dident know what happened so i havent bought another clam since, i came across some reading that may lead me to believe that the snails i bought as nassarius snails may infact be welks. So my question is how do you tell the difference between a nassarius snail that wont eat clams and welks??

thanks
alex

 

[a4twenty]

the simplest method is to watch when / where the snail spends most of its time and how he behaves. nassarius snails spend almost all their time in or on the sand and glide effortlessly across the top looking for food. whelks on the other hand are nocturnal and spend most of their time up on the glass or rocks, only crossing a sandbed when necessary and move much slower than nassarius do.

nassarius snails will definitely attack a dieing or even a severely stressed clam, it's why they make such a good member of the CUC.

try to post a couple of close up pics of the snails in question, for a positive ID.

 

[phil519]

agreed...also post up whatever other inverts/fish you might have. For all you know - one "reef safe" fish decided to get clam sashimi.

 

[Good Alex]

here are some pictures.

and a list of my fish/inverts in the tank.
yellow, achilles, and purple tang.
lyretail anthias
clowns
neon goby
flame fish
chromis
midas blenny
cleaner, and blood shrimp
emerald crabs
serpent starfish, NOT bristle
astrea snails
hermit crabs and
the "nassarius snails"

 

[Good Alex]

as far as behavior, ive seen them on the glass before, havent seen them on the rocks, they are usually on or below the sand with their syphon sticking out.

 

[a4twenty]

those are nassarius, they lack the pattern and operculum ( trap door ) of a whelk as well as exhibiting the normal behaviour of a nassarius snail.

from your list there are a few potential nippers,

the PT and MB have been known to be a problem, not always but the potential is there.

is the flame fish a flame angel? they are a known clam nipper

what colour is your serpent star??

the truth is, it is very hard to say what caused the demise of the clam without pictures of the clam before death and some info leading up to the death. the good news is that it wasn't likely the nassarius snails, they were just there doing their job as part of the CUC.

HTH

 

[Good Alex]

sorry i ment firefish, Nemateleotris magnifica, i have a small school of 3 or 4.

the serpent is grey.
thanks for your help. guess i learned a lesson here.