Sand sifting sea star… killing cerith snails?

[ZzyzxRiver]

I ill-advisedly got a sand sifting star for my 16g biocube (I keep falling for the LFS sales tactics), and in the couple weeks since I got it, all 4 of my cerith snails have gone missing. Not even a shell. It seems inconceivable that a snail could be predated on by a star… could it?

Other livestock:
2 perc clowns
1 YWG
1 red scooter blenny
1 cleaner shrimp
1 peppermint shrimp.
1 Trochus snail
4 astraea snails.
1 Tiger conch

Everything else in the tank seems perfectly happy. What could be going on?

 

[Mr. Mojo Rising]

They could be crawling out of your tank.

 

[ZzyzxRiver]

They could be crawling out of your tank.

I have a lid! But I will look in the back of the tank to see if any flipped over.

 

[PharmrJohn]

I'm concerned about your sandsifter starving out. Generally, they do such a good job at cleaning the sandbed, they end up exhausting their food source. Especially in a small tank. IMO, your LFS should never have sold you the star.

 

[ZzyzxRiver]

I'm concerned about your sandsifter starving out. Generally, they do such a good job at cleaning the sandbed, they end up exhausting their food source. Especially in a small tank. IMO, your LFS should never have sold you the star.

Oh, believe me, I’m never buying livestock from this place again. I’m working on rehoming the star. Any takers in Orange County, CA?

 

[PharmrJohn]

Oh, believe me, I’m never buying livestock from this place again. I’m working on rehoming the star. Any takers in Orange County, CA?

Excellent. Yeah, it's one of my pet peeves where an LFS will care so little about the lifeforms they keep that they will purposefully consign them to death. I hear that perhaps a 200g+ MAY support it, but when my 200g goes up, I'm avoiding them. I just don't see a 48x39x1 inch sandbed maintaining it for long.

 

[ZzyzxRiver]

In other news, my plan worked: I posted this thread, went out for errands, and came home to all four ceriths bussing around the rockwork like nothing’s ever happened.

 

[ISpeakForTheSeas]

I ill-advisedly got a sand sifting star for my 16g biocube (I keep falling for the LFS sales tactics), and in the couple weeks since I got it, all 4 of my cerith snails have gone missing. Not even a shell. It seems inconceivable that a snail could be predated on by a star… could it?

Haha, actually a number of starfish do eat snails, just the sand sifting stars we get in the hobby typically don't (there are a few species that pop up now and then that definitely do though). The stars can't digest the shells, though, so those get spit out after the snail itself is digested.

You're right to be concerned about your star starving - do you have any pics of it? There are a couple of different stars in the hobby that go by the name Sand-sifting Starfish, so pics of it (particularly of the top of it) can help us know which you have, and that may impact the feeding somewhat.

Anyway, for the best care advice I can give at this point (which may or may not be good advice; no one has gotten back to me on it yet):

These starfish don’t eat algae in any meaningful quantities. They’re probably carnivorous, but may be detritivorous (see the quotes below). Personally, I’d try putting the star in an acclimation box with a dish of sand for it, and I’d try offering it a bunch of mollusks for it to eat (clams, mussels, oysters, and small but meat-eating snails like Nassarius snails would be my suggestions at this point), and see if it shows interest in eating any of them. If it does, then I’d try offering it more of that item in various sizes and see if it has a preferred food size.

I'd try something like clam, oyster, etc. and/or snail meat (you can find various frozen/live marine snails to try online, including conch meat, periwinkle snails, babylonian snails, etc.)

The quote below is specifically geared toward Astropecten spp. (predatory) sand sifting stars, but there is another genus of sand sifting stars called Archaster that is thought (importantly the diet was inferred, not studied in the research that this diet was pulled from) to be detritivorous (specifically, they are thought to be microphagous detritivores). I have heard but cannot confirm that Archaster spp. misidentified as Astropecten spp. may be more common in the hobby than actual Astropecten spp. are.

So, with this in mind:
- If your star is detritivorous (which may be a very big if), then you would likely want smaller foods than the suggested below (which is designed for predatory sand sifters). In this case, I'd suggest trying to mix something like TDO Chroma Boost into the sand for your stars to find.
- If your star is predatory (which may to our limited knowledge be possible at this point even if it is an Archaster sp.), then the below advice (and my advice above) is more likely to be useful.
- If your star is actually primarily a biofilm eater like Linckia spp. Protoreaster nodosus, etc. (which may also to our limited knowledge be possible for an Archaster sp.), then it's likely to die regardless of what you do or don't feed it at this point.

I’ve heard they climb the glass when they’re looking for food and can’t find any in the sand bed.

Generally, people recommend large tanks and waiting until your tank is established before trying these (or pretty much any) sea stars, and the star survives on detritus in the tank. Unfortunately, even in a lot of these tanks, after they finish clearing the detritus from the sand, they typically starve.

My current advice to avoid the star staving - which may or may not help, I genuinely don't know at this point (it could take someone months to years of testing it to find out for certain, as sea stars can last months without food):
Target feed the star things like clam on half shell, oyster, mussel, scallop, etc. (bivalves); snail, whelk, conch, etc. (sea snail gastropods); and a good quality omnivore food (like LRS Reef Frenzy or Fertility Frenzy). These are - according to the best sources of information I can find - the sorts of foods sand sifting stars consume in the wild, and the star should swallow these foods whole if they aren't too big - you might need to experiment a bit with the size of the pieces offered to get it sized just right, but generally I'd say err on the smaller side.

If you decide to give it a shot, let me know how it goes, and keep me updated on the long term survival of the star!

Edit: To add:
Also, here are some signs to watch for to help track starfish health:

Some ways to potentially gauge the health of the starfish that may be useful:
1 - Visual: is anything visually wrong with the specimen? (From what I know of starfish, these cues are generally pretty obvious if they're there at all - if the starfish is disintegrating, there's something wrong).
2 - Weight: is the specimen putting on or maintaining weight (generally healthy), or is it losing weight (under most circumstances, this would be unhealthy)?
3 - Size/Length: if it's not already full size, is the specimen growing? Is it shrinking (either from weight loss, disease, limb loss, etc.)?
4 - Reproduction: is the specimen engaging in reproductive behaviors/activities (i.e. courting, nesting, spawning, etc.)? (I recognize this one is not as common of an indicator in captive starfish at this point, but there are a few instances of starfish attempting to spawn in captivity).
5 - Longevity: is the specimen relatively close to meeting, actually meeting, or exceeding their expected wild lifespan (or at least surviving for a few years - healthy), or is the specimen dead/dying prior to doing so (unhealthy)?
6 - Speed: how quickly can the specimen right itself when it's flipped over?
7 - Level of activity: how much is the specimen moving around? (Generally speaking, low activity indicates poor health; moderate activity indicates good health; and high activity indicates good health but probable stress - it could be searching for food, oxygen, etc., but it's probably not in terrible health when moving a lot).
8 - Grip strength: does the specimen have a strong hold/grip with its tube feet? (A strong grip indicates good health, a weak grip indicates poor health).
9 - Willingness to eat: is the specimen eating? (Seems obvious, but can be really hard to tell with some stars - some stars leave little trails called feeding scars through the things they're eating; sometimes you can see their everted stomachs; other times, like if they're feeding on biofilm, you may not be able to tell at all - them crawling onto visible food is a good sign they're willing to eat, but - as mentioned above - the food may or may not meet their nutritional needs).

And a final note on starfish keeping:

One important thing to keep in mind with foods for these guys - just because they eat it, doesn't mean it's meeting their nutritional needs; it might be, but it might not be. With how long it seems to take these guys to starve, unless you're monitoring their health closely, you might not notice if it's not meeting their needs until it's too late.

 

[ZzyzxRiver]

Thanks for all the info, @ISpeakForTheSeas ! The farther-away-but-better-LFS said they’d take it off my hands. Hopefully with all your help I can see if my upcoming upgrade to 50g can support a different star!

 

[ISpeakForTheSeas]

Hopefully with all your help I can see if my upcoming upgrade to 50g can support a different star!

As a general rule at this point, for tropical starfish, the less reef-safe/more predatory they are, the easier they are feed (though that doesn't mean it's easy).

My recommendations for starfish at this point are either Aquilonastra ("Asterina") starfish - some of which are known to eat corals - or brittle/serpent starfish (Ophiuroids), as these both seem to do well while other tropical stars don't yet (hopefully we'll figure out how to meet their dietary needs and that will change going forward though).

 

[ZzyzxRiver]

My recommendations for starfish at this point are either Aquilonastra ("Asterina") starfish - some of which are known to eat corals - or brittle/serpent starfish (Ophiuroids), as these both seem to do well while other tropical stars don't yet (hopefully we'll figure out how to meet their dietary needs and that will change going forward though).

I’ve got a couple of each of those, but they don’t have the “wow, a sea star!” impact, you know? You barely notice them. But such is life. Plenty of other cool critters! I’m just glad I was able to find somewhere to send it before it starves.

 

[ISpeakForTheSeas]

I’ve got a couple of each of those, but they don’t have the “wow, a sea star!” impact, you know? You barely notice them. But such is life. Plenty of other cool critters! I’m just glad I was able to find somewhere to send it before it starves.

Definitely agree - they're cool, but not the same as the bigger, true starfish.