"Ninja star" / Lithopoma ("astraea") phoebium / longspine star snail superthread

[3sxp]

Hi all. Is anyone, like me, particularly interested in the so-called "ninja star" snails? I have a couple of them and my family loves them. One of them laid eggs a couple of weeks ago ( https://www.reef2reef.com/threads/eggs-on-glass-snail-clownfish.988582/ ) which hatched, but the larvae vanished and I assume were eaten. I'm very interested in the exploration of breeding them in captivity since they're on the list of ones that are not available domestically ( https://www.reef2rainforest.com/201...ed-marine-invertebrate-species-list-for-2018/ ).

So I'm just digging around trying to read about them and thought I'd start a single thread just about them, since I didn't see one.

A couple of threads here have discussed their species ID:

Collecting a clean up crew in Pinellas county Florida

Hey all, I am going on vacation to Pinellas county, FL and want to collect a clean up crew while there. I have read through many of the threads on this forum and others and there is a lot of contradictory information. Here is the fish and wildlife page of FL specific to recreational marine life...

www.reef2reef.com

Apparently, asterina stars are not asterinas, and astraea snails are not astraeas.

Asterina stars are actually of the genus aquilonastra, and astraea snails are from the genus lithopoma. Aquilonastra Conandae Asterina Fimbriata Lithopoma Americanum Lithopoma Tectum Astraea Heliotropium, the only valid species of astraea

www.reef2reef.com

Trochus sp?

I got these from an LFS described as a Trochus species, but looking online I couldn't find any Trochus specimen with a shell like this. They're diligent little buggers, infinitely more productive than my astreas and I want more of them!

www.reef2reef.com

The WORMS page:

WoRMS - World Register of Marine Species - Lithopoma phoebium (Röding, 1798)

www.marinespecies.org

Here's the main wikipedia page:

Lithopoma phoebium - Wikipedia

en.wikipedia.org

When I get a chance I'll dig around for biology papers about them.

Random stuff I'm curious about:
1) What's happening to the larvae after they hatch? (are they starving? being swept away? eaten?)
2) Generally how do they reproduce? Under what conditions?
3) How many varieties are there and where are they from? (Some look more like astraeas and some look quite flat and very different; seems to be a lot of variation in spine length, number of spines, etc)

Here's a photo of mine when I first got them, since what's a thread without a photo?

 

[Stomatopods17]

Random stuff I'm curious about:
1) What's happening to the larvae after they hatch? (are they starving? being swept away? eaten?)
2) Generally how do they reproduce? Under what conditions?
3) How many varieties are there and where are they from? (Some look more like astraeas and some look quite flat and very different; seems to be a lot of variation in spine length, number of spines, etc)

It depends on how these spawn.

Some snails release their eggs/semen into the water column and they fertilize and settle, others lay their eggs and then they hatch into free floating planktonic larvae.

In both scenarios they're destroyed by filtration, eaten by fish (even other planktonic species you can't see, corals, hydroids, etc). In the former scenario you may get really lucky and have a few babies that settled instead of being eaten/filtered due to how fast they just become normal tiny snails, but the other is impossible to do in the normal display and would need eggs transported into a separate system that's kept stable, target fed some unknown planktonic product until they settle, and void of any threats to their health such as using a sponge filter over other filtration, no other animals, etc. I do not know which one these snails fall under.

Them reproducing is the easy part.

 

[3sxp]

It depends on how these spawn.

Some snails release their eggs/semen into the water column and they fertilize and settle, others lay their eggs and then they hatch into free floating planktonic larvae.

In both scenarios they're destroyed by filtration, eaten by fish (even other planktonic species you can't see, corals, hydroids, etc). In the former scenario you may get really lucky and have a few babies that settled instead of being eaten/filtered due to how fast they just become normal tiny snails, but the other is impossible to do in the normal display and would need eggs transported into a separate system that's kept stable, target fed some unknown planktonic product until they settle, and void of any threats to their health such as using a sponge filter over other filtration, no other animals, etc. I do not know which one these snails fall under.

Them reproducing is the easy part.

Right. Thanks for the reply!

Based on what I saw -- I wish I'd gotten a video of it, but there were eggs on the glass, and the eggs hatched, and seemed to hatch into larvae, some of which stayed on the glass and could be seen moving around. Then a couple of days later they were all gone.

It's going to be awhile before I could mess with anything like this, but I was thinking of moving this pair into an external refugium connected to the main tank. For the moment I'll just see if they do it again and at what interval. There didn't seem to be a safe way of removing the eggs from the glass without damaging them or I'd've tried.

 

[ISpeakForTheSeas]

Random stuff I'm curious about:
1) What's happening to the larvae after they hatch? (are they starving? being swept away? eaten?)
2) Generally how do they reproduce? Under what conditions?
3) How many varieties are there and where are they from? (Some look more like astraeas and some look quite flat and very different; seems to be a lot of variation in spine length, number of spines, etc)

Based on what I saw -- I wish I'd gotten a video of it, but there were eggs on the glass, and the eggs hatched, and seemed to hatch into larvae, some of which stayed on the glass and could be seen moving around. Then a couple of days later they were all gone.

1) If some of the larvae hatched as benthic larvae, then those most likely either starved (unlikely if they were benthic larvae in a tank where the adults were healthy enough to spawn) or were eaten; assuming that they all hatched as planktonic larvae, then likely yes to all of the above, unless they're lecithotrophic like Lithopoma undosa. (As mentioned, rearing larvae in a regular tank is basically guaranteed to fail.)

2) Good questions: I don't think anyone knows. Some things that can impact/trigger spawning include light schedule, light spectrum and intensity, temperature changes (both rapid - i.e. temperature shock - and slow), moon phases, tides, water conditions (i.e. calm water, stormy water, etc.), salinity, chemical cues, seasons, dessication, flooding, etc. - if you can figure out which cues are important for this species, that would be a great first step toward rearing them. For Lithopoma undosa, they were able to induce spawning using UV treated water and temperature shock,* so those would likely be good places to start your search.

3) I have no idea; some may be different species, others may be regional phenotypes, the species may just have a wide range of phenotypic expression, etc. Again, good questions, and one which could potentially be answered through aquaculture of the species.

P.S. The paper below has a lot of good info, so I'd give it a read if you decide to try rearing these guys.

*Source:

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1749-7345.2009.00268.x