Easy way to distinguish btwn Crocea and Maxima?

[colberag]

If you see a young (2'') clam in a LFS, how can you tell if it is a Crocea or a Maxima or something else? Just curious because I want to make sure I don't end up accidently buying a clam that will get huge.

 

And before anybody responds with "Just look at the label" - i looked at the label when I bought my "Royal Gramma" when I first started, which turned out to be a bicolor dottyback (that was before my NR.com days, I would never make that mistake now )

[JustReef]

Croceas have a relatively smooth shell, maximas have ridges on their shell.

[BKtomodachi]

At 2", though, it is tough. Even squamosa can be difficult to distinguish at such a small size. All tridacnids will have scutes like mature maximas until they are maybe 1.5" or so.

[tinyreef]

agreed with bk, at 2" both the max and croc might have scutes. the crocs typically wear them down to smooth when they burrow into the rock. they can develop pretty pronounced scutes too ime.

 

maybe you can tell by comparing the byssal opening (if you can see them/pick them up). the croc's byssal opening is more pronounced for its size than a max's. e.g. a 2" croc's byssal opening might be the size of a 4" max's.

 

but it's tough to ID at that tiny size.

[SPS20]

My croceas have some very pronounced scutes, so that isn't a very good way to tell, IMO.

 

The easiest way to tell, IMO, is to look at the shape of the shell from the side. Maximas look a little more elongated along the axis of the underside of the shell, where the byssal opening is. Croceas look "fatter" and less stretched along that axis. I'm not sure if my description is making sense, but if you look at a crocea and a maxima side by side, you would see what I mean.

[Reef Goddess]

Maximas tend to have symmetrical patterns (spots, lines, etc) on their mantle compared to croceas and more scalloped/circular mantles. Croceas often have fleshy protrusions from their mantle and a soft wavy shaped mantle.

 

Croceas

 

Maximas

[hazmat]

Good thread because I thought I bought a Crocea and I think I have a Maxima. Whatever it is it's doing really well so I guess it doesn't matter.

[dtfleming]

i agree with josh and reef gardner, both are good ways to distinguish them apart.

[basser1]

Here you go:

 

http://www.reefkeeping.com/issues/2002-07/...ature/index.php

 

This was from reefkeeping mag. it has excellent pics and descriptions!

[colberag]

Thanks for all the info! I like that reefkeeping magazine article - very informative.

[iNano]

croceas tend to have more ripples on their mantle, and if you look in their mouth you can see their guts. they tend to be more oblong too.

[Daemonfly]

http://www.reefaquariumforum.com/viewtopic...?f=1&t=1994