IOTM: Seastars Part I

ophiura

Active Member
Thanks to SCOTTS and others for some motivation to write some of this up
And I'll count on many of you to provide pictures of your stars!
This is Part I on a series to cover Seastars and Brittlestars...perhaps someday their other relatives
Part I covers the "reef safe" seastars such as Linckia. Other parts will cover non reef safe stars, sand sifters, etc.
Google some of the bold faced terms for cool info.

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Guide to the ‘Stars: Seastar Care and Selection
There are several common classes of echinoderms (which means “spiny skin”) in the aquarium hobby. They include sea urchins (Echinoidea), sea cucumbers (Holothuroidea), brittlestars (Ophiuroidea) and seastars (Asteroidea). Less commonly seen and kept (for good reason) are the featherstars (Crinoidea).
Though these critters don’t look very similar at all, they are related. Clearly, searstars, urchins and brittlestars all have the “spiny skin” characteristic of the group. Sea cucumbers do not appear to have these spines, but that is because the skeleton is reduced, and embedded in the skin. Echinoderms have an internal skeleton composed of calcium carbonate, but they are still invertebrates. The skeleton is covered to a greater (eg sea cucumbers) or lesser (eg seastars) degree with a layer of living tissue. This prevents things from settling on the animal and growing there. Several classes have fascinating structures to deal with “fighting off” critters that may want to settle on them including the pedicellaria
of urchins and some seastars.
Echinoderms also have pentamerous
or “five part” symmetry, which is pretty clear in certain classes. This does not necessarily mean that all seastars must have 5 arms, however. There are exceptions to this. They have an internal hydraulic system called the water vascular system
or WVS. The WVS includes the tube feet you see the animal using to move. This system is used in locomotion, feeding, respiration and excretion. An additional “cool fact” is that echinoderms possess a fascinating type of connective tissue called mutable collagenous tissue
. It is extremely interesting to scientists because the animal can control the mechanical properties of this tissue at will. It can become extremely firm, so as to “lock” spines in place; it can become extremely weak, allowing the arms of brittlestars to not break, but literally fall off if threatened.
The specific purpose of this series for the Saltwaterfish.com forum is to cover seastars and brittlestars which, though they seem somewhat similar, are actually different classes of animals. There are several differences. Primarily the arms and central disk area of seastars are continuous whereas the central disk of brittlestars is very distinct from the arms. There are also anatomical differences in the tube feet, and movement in general.
We will start with covering a specific group of seastars. Seastars (aka “starfish”) are a very diverse group of around 1800 species. Of this only a small handful end up in our tanks, whether intentionally or otherwise. They exploit a diversity of feeding styles which is important to consider in selecting one. Will it eat corals? Will the fish I keep eat the seastar? Important questions to know. Additionally, water quality is critical to keeping ANY echinoderm healthy. They are especially sensitive to salinity fluctuations.
 

ophiura

Active Member
Part 1: The reef huggers: Linckia, Fromia, Nardoa and relatives.
Examples:
Linckia laevigata (Blue Linckia)
Linckia multiflora (Common name?)
Echinaster echinophorus (Knobby star)
Tamaria stria (Purple Linckia)
Echinaster luzonicus (Burgundy Linckia, possible Red Linckia)
Fromia milleporella (Red Bali Star)
Fromia elegans and other Fromia stars
These stars are very similar in their requirements, so I will just give a synopsis of care that applies to most. The first question the hobbyist should ask is “do I have the minimum requirements for this star.” Keep in mind that what we perceive to be the “minimum requirements” is based not on what we know about the animal in the wild (we know little) but on general experience of other hobbyists. The fact is we don’t know specifically what these stars are eating, except to say that they feed on something growing on surfaces…live rock or glass. It might very well be algal/bacterial films, or the critters (microscopic) that feed on it. However, it seems clear that they are not eating nuisance forms such as hair algae and slime algae…otherwise many of us would keep them indefinitely! But this does not happen. There is a whole food chain beyond our sight just thriving on all surfaces in the tank. Just seeing a star on a certain patch does not mean that it is eating the algae or detritus.
The diet could also consist of encrusting sponges, bryozoans or a number of other fauna found on healthy LR. It seems we can propose a general correlation: the more healthy “growing” LR one has, the longer these stars live. The honest fact is that MOST do not take to spot feeding. Sometimes an individual star will, and this may explain why they are kept in some smaller tanks, but do not rely on this. It helps to try to spot feed, just in case, but don’t count on it.
So a large reef tank seems to be fundamental. But success is also related to competition in the system – a relatively large animal needs a lot of microscopic food to sustain it, and having more than one of these animals can cause both to starve faster. How long until starvation sets in? Well, it has been estimated that a healthy wild caught star will die of starvation in 8-12 months, after in digests much of its internal structure. It may be difficult to believe, but it is the nature of their metabolism that they can “survive” so long while starving. Keeping the animal 18 months is now becoming more of a benchmark for success with it.
So for many of these stars, it is safe to give a minimum tank size and a rough estimate on LR. What other factors should be considered? The age of the tank and water quality are also paramount considerations. Keep in mind that this is a hobby requiring dedication and patience. Many animals die out of the impatience of the hobbyists. There are many “things” in water that we do not test for that can impact certain animals. Many tangs and angels, for example, do not fair well in younger tanks. The same is true of these stars. A minimum tank age, in my opinion, is 6 months. It gives time for some stability to develop in both the tank, and the maintenance schedule of the hobbyist. You learn the nuances of your tank during that time, and to eliminate major fluctuations.
Specific gravity (or more precisely salinity) is a crucial factor. These stars seem to do better in systems with higher specific gravity than that encountered in many fish only systems. A rough estimate is 1.025-1.026, but this of course is dependent also on the temperature of the system.
 

ophiura

Active Member
Let’s say that you’ve researched, and decided your tank is suitable. If you are able to shop locally for a specimen, look for a few key things. An animal that has been at the store for more than a few days is a good place to start. Ideally, it will have been there a few weeks, in a reef tank, with no signs of trouble. Well, wishful thinking but it does happen. The animal should be bright, without any “deflated” appearance to the arms (most obvious in Linckia and less so in the “flatter” Fromia). It should show no signs of degradation or whitish patches anywhere, especially on the arm tips. The arms can, however, be unequal. Also look for parasites such as Thyca, embedded in the animal.
It is also important to ask the specific gravity of the system it is on. If it is significantly low (typical fish only levels of 1.019 to 1.023) then it might be something to worry about. If it is this low, but the animal has been there several weeks, then you may wish to consider setting up a small QT (with no history of medications) to slowly acclimate the animal to your tank salinity over several days. It is large “jumps” in salinity, even if done over several hours, that is probably a major source of mortality in these animals.
At this time two “wive’s tales” can be addressed: not exposing the animal to air, and not handling the animal without gloves. Neither of these is fatal, but should obviously be minimized. I believe these started in an effort to explain the high nearly immediate mortality rate of these animals in captivity…without considering the obvious (acclimation). Healthy seastars are actually relatively unlikely to develop diseases and can have large wounds or arms bitten off without issues. One hypothesis about the high mortality, in addition to acclimation shock in general, is an inability of some stars to adapt well to synthetic saltwater.
So now you have the star at home. A major factor with these stars is the need for a long acclimation. Standard acclimation is generally several hours, especially if there is significant difference in water parameters between the vendors bag and your system. A drip method is best, but be sure to address temperature fluctuations as well. It does little good to drip acclimate for hours to match salinity and pH, while temperature is dropping in the container.
The first month after introduction is critical. Even if the animal seems active, many will die within the first month from acclimation shock. This could be due to acclimation on your end, or at any number of points between collection and arrival at your home. Needless to say, many do not survive. And in most cases, damage may be done before the animal even gets to your tank. Any signs of whitish patches or holes, especially at the arm tips, should be a source of concern. These animals die by a characteristic "melting" or disintegration. Often they look very flat or sunken in the arms, when they should be quite robust and cylindrical. These symptoms may also indicate other problems, such as starvation.
Once the animal is established, be aware that any large fluctuation in the tank (such as may occur in a large water change) could “reset the clock” for osmotic shock. If you significantly change the pH, specific gravity, temperature, etc suddenly, this is a new stress on the animal and it could in theory die from it. Be very careful when doing water changes to prevent significant fluctuations.
Quick minimums:
- “Pristine” water conditions especially related to specific gravity (1.025-1.026)
- Large, mature reef tank, at least 6 months old
- Ideally a minimum of 150lbs or so of LR. Some can have less, some will need more. But if you have a small tank, IMO under 100g, really think hard. Blue Linckia need some of the largest tanks.
- Long acclimation time
Got a question or problem? It helps to provide the following from the outset:
- Provide SPECIFIC tank parameters, age, etc
- Type or color of star
- How long you’ve had it
- Amount of LR
- Inhabitants of the tank
- Recent water changes or perturbations in the tank
 

hot883

Active Member
Ophuria, mine loves to bungie jump off the side near the top. He's very fun to watch. My favorite part to see him do a gymnastic back flip by displaying his Yoga talents. When he has had enough entertaining, he will decide to bury himself. You can actually see the sand pouring up to the surface of his body around his arm pits and then he is GONE!
My LFS has a basketstar.
Thats an awesome animal
I'm sorry, Great Article. Thanks

 

ophiura

Active Member
Thanks for your pictures of your sand sifter star! I'll be getting around to writing something on those guys soon, I haven't forgotten them!
 

hot883

Active Member
Originally Posted by ophiura
Thanks for your pictures of your sand sifter star! I'll be getting around to writing something on those guys soon, I haven't forgotten them!

My LFS told me it was a sea star! Was that another LFS lie. Ha!
 

celacanthr

Active Member
very good ophiura!!!
way better than mine!
does this mean i should wait until november to do the sea anenomes: IOTM?
 

ophiura

Active Member
Were you doing one on seastars? I thought anemones?
We don't have to be real precise on when to change them out, IMO. I would write something up in a word document or something and be able to run with it. We don't have a real line up of these things so hope there are no hard feelings. I started writing some of these up a loooong time ago, just got around to finishing it up a bit.
 

celacanthr

Active Member
oh i was going to do an IOTM on anenomes, for oct. but i think i'll spend the time researching, for an invertebrate cnidarians are pretty complicated! :notsure:
 

beth

Administrator
Staff member
Excellent info!
And, if you don't mind, I'll add this to our Archive with continuous posting abilities.
 

hot883

Active Member
Originally Posted by CELACANTHr
i thought that feather stars and basket stars where the same thing?
My LFS had a "feather star" as well and they looked like a curled up taranchula (sp) and the basket star looked more like a tangled piece of netting or something. The owner dipped in some cyclopeeze and the feather start opened up and was AWESOME!
 

ophiura

Active Member
Feather stars and basket stars are actually different. Feather stars (aka "sea lilies") are in the class Crinoidea, while basket stars are ophiuroids - basically a very different looking brittlestar. When I get into the brittlestars, I'll probably work on making this distinction. Feather stars are virtually impossible to keep in tanks...basketstars are exceedingly difficult and require very focused care, but are not impossible to keep with a great deal of attention.
During the day, both of these types of animals will be hidden and curled up, but at night they will come out and open up. Both are large filter feeders. But the crinoid has a very particular diet, rarely met in captivity, and nearly all will die within a year after a long starvation.
 

beth

Administrator
Staff member
Yes, I was tempted by the beauty of a crniod once and picked up one at the local pet shop [an already doomed creature]. He seemed to do well for a few months, then suddenly went to melt down....literally melting down alive. It was a sad, pitiful site.
At one point, I let my tank really go natural with sagassum growing out of LR and flowing at will in the water column. The crinoid nightly would come out, crawl up the stalks of sagassum and suspend there waving in the water for about an hour trying to catch food. When the sagassum finally died off, then the crinoid started to fail.
I would not recommend this creature for any hobbyist. It not only has a poor survival rate, it basically has next no survival rate in captivity. I know of only one hobbyist who had managed to keep one for more than just a few month.
 

kosarfan

Member
This critter seems to be extremely easy to take care of. Every time I feed he comes out for the food and I drop shrimp pellets which he eats very quickly. He is growing by leaps and bounds - at least has doubled in size in the last 8 months. I have him in with a yellow tang, sand sifting goby, chalk bass, blue-green chromis, 6 line wrasse, and cleaner shrimp. I have heard rumors that the green brittle stars can cause problems but have not encountered any as of yet.....should I worry? I even take him out sometimes at the request of my nieces and nephews so they can hold him - he doesn't seem to be bothered by it at all.
I also have a serpent star that is a darker grey color. He comes out for food just like the green brittle and sometimes the green brittle star will hold down the darker serpent star with one arm while the green takes all of the food. Usually the stars don't hang out together but about once a month they are practically on top of eachother and the smaller darker serpent star doesn't seem to mind.
Those two stars definitely add a lot of character to the tank.....hope I don't have to get rid of them - fearfull that the green is getting big.
 

hot883

Active Member
Originally Posted by kosarfan
This critter seems to be extremely easy to take care of. Every time I feed he comes out for the food and I drop shrimp pellets which he eats very quickly. He is growing by leaps and bounds - at least has doubled in size in the last 8 months. I have him in with a yellow tang, sand sifting goby, chalk bass, blue-green chromis, 6 line wrasse, and cleaner shrimp. I have heard rumors that the green brittle stars can cause problems but have not encountered any as of yet.....should I worry? I even take him out sometimes at the request of my nieces and nephews so they can hold him - he doesn't seem to be bothered by it at all.
I also have a serpent star that is a darker grey color. He comes out for food just like the green brittle and sometimes the green brittle star will hold down the darker serpent star with one arm while the green takes all of the food. Usually the stars don't hang out together but about once a month they are practically on top of eachother and the smaller darker serpent star doesn't seem to mind.
Those two stars definitely add a lot of character to the tank.....hope I don't have to get rid of them - fearfull that the green is getting big.
Kosarfan, are they aggressive?
 

sterling007

Member
Opihura, glad to see you still tell everyone to avoid the basketstars........beautiful, but......so difficult.....I kept mine alive alot longer than the Shedd did once I gave it to them.....I think because I babied it so much. I don't think anyone at the Shedd stayed up until midnight to feed it.
 

sterling007

Member
P.S. I bought a harlequin star a couple of years ago, haven't seen it since, ah-ha came out the other night and was peering in tank with flashlight (stalking) and low and behold!! there it was...thought it had perished long ago.
 

ophiura

Active Member
Sterling - you are always the person I think of when I mention the dedication required to try and keep one
Quite admirable

I will be covering the basketstars, along with brittlestars and serpentstars at a later date....
Bang Guy - an interesting beastie...how long have you had it?
 
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