A Challenge to Anti Linckia-ism

[Formulator]

I hear a lot of folks say we shouldn’t keep Linckia stars because they starve to death or we don’t know how to keep them alive and they just die within a year or so. I decided to read up on the subject and found a peer reviewed scientific article which described the lifecycle of these stars. Apparently their juvenile state is cryptic (hidden, not easily found or farmed) and lasts about 2 years. They come out of hiding when they have reached sexual maturity. Therefore, 100% of the stars we buy are sexually mature specimens, meaning they are AT LEAST 2 years old when we put them in our tanks. If we assume the age of mature specimens harvested for the aquarium trade is a bell curve, and their overall lifespan is about 10 years, then a majority of the stars we get are 5-7 years old by the time they get into our tanks.

So, I would propose that keeping one for a year or two amounts to keeping it alive for a respectable portion of its remaining lifespan. One that I would call a success, and not any more unethical than the hermits and other inverts we often keep and accept that they will live a fraction of their lifespan compared to those left in the wild.

Of course, I am no expert and would gladly accept rebuttal. Just sharing where my thinking is at after some very light research on the topic. Thoughts?

 

[CO2TLEY]

Following. I was just doing research about them yesterday. Interesting info

 

[mues]

One might also argue that they reproduce asexually through dropped limbs as well and do not fare well that way either.

I think a lot of it has to do with their sensitivity to changes. There are simply species that do not do well in captivity. "Small" changes in our systems are dramatic changes in some local ecosystems. The species has been known to do poorly in a number of different changes (O2, temp, salinity, you name it)

 

[Malum Argenteum]

If 100% of the stars we collect are sexually mature, we should be collecting smaller ones since removing sexually mature animals is hardest on populations.

So, I would propose that keeping one for a year or two amounts to keeping it alive for a respectable portion of its remaining lifespan.

Well, it amounts to starving it to death over a year or two, which might make 'respectable' a little misleading since there's the evaluative sense of that word that might be overstating the case.

Does the average linckia live for a year or two after it is harvested? Count deaths all along the supply chain when calculating for accurate numbers. When I worked in an LFS, they virtually all melted in transit or shortly thereafter.

 

[Mr. Mojo Rising]

If you want one go buy one...

But even if your 'assumptions' are correct, one year out of 10 - 10% of the normal lifespan - is not success in my book. I say just leave them in the ocean to enjoy their 10 years.

Clownfish lifespan is 10-12 years, but I've met so many that are about 20+ years old, THAT to me is success and what I strive for. And I have kept inverts alive longer than the normal life span also.

 

[ISpeakForTheSeas]

Yeah, in addition to the fact that they seem to be starving, I question the 10 year lifespan for two reasons:

1 - there aren't any proper studies I can find on their actual lifespan in the wild (so the 10 year thing seems to be a guess).

2 - while they grow fast as juveniles/larvae, they seem to only grow ~2.4 mm per year as adults; given that they become adults (i.e. sexually mature) at ~50 mm at ~2 years old, that would seem to indicate to me that they would live closer to 23 years in the wild.* [Edit: I should say here, that 23 years would be until the stars grow to the average adult size of ~96.6 mm; the largest star found in the study was 133.0 mm, so they could potentially live for ~38 years at the max size I've seen listed.]

To add to this, even if they did only live a decade, keeping one for just 1 year - very few people are able to keep them for more than ~13 months - (and having it slowly starve to death that whole time) when it comes in at 5-7 years old and has 3-5 years left in the wild seems like something I personally wouldn't call successful.

Regardless, as mentioned, the ones that survive shipping (which a lot die before they ever reach our tanks) are slowly starving to death in our tanks and are definitely not thriving - if they were thriving, we'd see spawning behavior and many stars living more than a year - so I can't personally view it as humane to keep them at the moment.

Personally, I currently recommend against trying to keep a tropical, true starfish (Asteroid) species, particularly biofilm-feeding species, except for Aquilonastra stars.

That said, if you're really determined to try keeping them anyway, I'd strongly suggest setting up an Aquilonastra farm, a cryptic refugium to farm sponges, and possibly a colonial tunicate farm as well (all of these should be separate from the Linckia's tank so they can't get to the farm and ruin the "crop") - the Linckias feed on these (they presumably emulate biofilms to some degree), and the most successful Linckia keeping I've seen have always involved at least one of these aspects (typically the Aquilonastra stars).

With Aquilonastra stars alone, I've seen people keep them 2-3 years; with the cryptic refugium sponges involved too, the longest I've heard is ~4 years. Still not good by my calculations, but arguably acceptable if they really only live a decade.

For those who are truly determined to keep true starfish against my recommendation, 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.

*Source:

https://core.ac.uk/download/pdf/5093827.pdf

 

[Formulator]

I'd strongly suggest setting up an Aquilonastra farm, a cryptic refugium to farm sponges, and possibly a colonial tunicate farm as well

This sounds like fun… I do appreciate the wealth of info you shared. The Linckias are just so beautiful and I’m like a kid in a candy store every time I see one at the LFS. I’ve never pulled the trigger because of all the challenges you mentioned, but it sounds like there is at least a pathway to successfully keeping them for a few years. I am a biochemist professionally, so am certainly up for a challenge involving complex refugia and maximum chemical stability. If I can talk my wife into annexing more of the basement into my fish room, I may just have to set up a Linckia food farm!

Also, forgot to share my source regarding the 2 year age of sexual maturity. It is open access here:
https://scholarspace.manoa.hawaii.e.../0ebcfe0f-0c98-42e4-bf8e-c3612e096092/content

 

[ISpeakForTheSeas]

I may just have to set up a Linckia food farm!

Just remember to keep the Aquilonastra away from the sponges and tunicates too.

Also, forgot to share my source regarding the 2 year age of sexual maturity. It is open access here:
https://scholarspace.manoa.hawaii.e.../0ebcfe0f-0c98-42e4-bf8e-c3612e096092/content

Yeah, that's the same paper as my link above - one of the few good sources of info on Linckias at this point.

 

[Malum Argenteum]

Personally, I currently recommend against trying to keep a tropical, true starfish (Asteroid) species, particularly biofilm-feeding species, except for Aquilonastra stars.

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Protoreaster sp do well in a FOWLR, in my experience. I've only ever kept a few, and a fair number of years ago, but I do not recall one ever dying in my care.

 

[ISpeakForTheSeas]

​

Protoreaster sp do well in a FOWLR, in my experience. I've only ever kept a few, and a fair number of years ago, but I do not recall one ever dying in my care.

Yeah, I've heard they do well for some people and not for others, but they typically do better in aquariums than most biofilm-feeders. They're not as reef-safe as most other biofilm-feeding stars though.

 

[Malum Argenteum]

Yeah, I've heard they do well for some people and not for others, but they typically do better in aquariums than most biofilm-feeders. They're not as reef-safe as most other biofilm-feeding stars though.

No, they're not reef safe, that's true.

 

[ISpeakForTheSeas]

No, they're not reef safe, that's true.

Ah, sorry, got my threads crossed or I would have elaborated:

There are true starfish (Asteroids) and there are brittle/serpent starfish (Ophiuroids) - brittle/serpent starfish do well in our tanks, true starfish don't.

As a general rule with true starfish, the safer the starfish, the more likely it is to die quickly.

Honestly, at this point, the only true, relatively reef-safe, tropical starfish in the hobby that I can recommend someone keep if they really want a true sea star are Aquilonastra stars (known in the hobby as Asterina stars).

Aside from Aquilonastra stars, the stars in the hobby either aren't reef-safe, will starve to death (typically within ~8-13 months), or both. So, unless you want Aquilonastra stars, I'd really stick with brittle/serpent stars.