OPHIUROIDS IN THE HOME AQUARIUM
Brittlestars (aka serpent stars) are popular inhabitants of home marine aquaria, but they have some specialized needs. In the aquarium literature, a distinction is made between "brittle stars" which apparently are those with (visible) arm spines and "serpent stars" which do not have visible arm spines. This is not a biologically significant distinction and is not made outside the aquarium community. In reality, the arm spines of "serpent stars" may simply be held close to the arms "or adpressed." In "brittle" stars, the spines are held perpendicular to the arm. While some common genera in the hobby do have small adpressed arm spines, a closely related animal may be considered a "brittlestar." Worse yet, it may vary from animal to animal! So, be wary of asking about brittle versus serpent stars; there may be no agreement on what you mean!
Arm base of a "serpent star" Ophioderma squamosissimum. Note the adpressed arm spines.
Be especially careful monitoring the salinity (specific gravity), pH and other chemical parameters of the tanks! Sudden changes in these will cause your marine pets serious harm (and not only the ophiuroids)! Proper acclimation is critical for all animals, but brittle stars are notorious for quickly dying after introduction. In this case, proper acclimation means a long, slow one. A 'drip" method is easy to do (take some airline tubing, tie a knot in it to get a slow, even flow rate). The acclimation should continue until the salinity in the container with the brittlestar is the same as that in your system. Often this may take 4 or more hours. Even if your salinity is the same in your system and in the store system, still take time to acclimate. Other parameters, such as pH and alkalinity may still vary, causing stress and death.
Also be aware that ophiuroids are part of the natural food chain, and may CONSUME OR BE CONSUMED by some fish, crabs, or other invertebrates in your tanks. Remember that, regardless of how well your tank is running, you have created an artificial environment, not recreated a natural one. Animals may not act as they would in the wild...it is much easier to "hunt" food in aquaria than in the wild, especially if the animals are not being properly fed.
I have seen a number of emails implicating brittle stars in all sorts of attacks on aquarium fish and inverts. They may in fact be guilty (the green serpent star, Ophiarachna incrassata, seems especially unpopular). For large specimens, it is wise to spot feed (using bits of fish, shrimp, etc). I would not leave the animals to scavenge, as many suggest. If they do not get their fill, they will hunt for something larger.
Please read about good tank species before buying! In particular, the 'red' serpent star (perhaps an Ophioderma squamosissimum) and the 'black' brittle star (perhaps an Ophiocoma sp.) seem more reliable. However, Ophioderma squamosissimum seems rather rare in the wild, so caution should be taken with over harvesting from the wild. Other, smaller, brittlestars often come as hitch-hikers on live rock or in live sand. Many of these are six-armed varieties (perhaps Ophiactis spp.) that reproduce by fission (they split in two). Such animals then have 3 arms that are shorter than the others. The small whitish brittlestar that is commonly seen is likely to be Amphipholis squamata , a self fertilizing hermaphrodite that broods its young. Under good conditions, this species will reproduce rapidly. They are excellent members of a sand bed community.
Larger species of brittle/serpentstars are not sand sifters, and do not eat sand bed fauna. The smaller species may burrow and eat bits of leftovers, but are considered very good additions to the tank.
Reefkeepers may wish to avoid the large green brittlestar Ophiarachna incrassata because of its notorious ability to hunt for other tank inhabitants. This is not something that is certain to happen, but it is possible. Some people report them consuming a wide variety of species, from snails to shrimp and fish, regardless of spot feeding.
In addition, I don't recommend keeping basketstars in aquaria. These ornate and beautiful animals have some special needs that are typically not met in captivity, resulting in a quick death. In the wild, these animals can live over 7 years. They can reach enormous size (over 3 feet), and require a heavy load of plankton in the tank. They are nocturnal feeders, so those keeping them often need to stay up after dark to spot feed the animal a variety of prepared and live foods. During the day, they often remain hidden. While they may very well feed on brine and mysis shrimp, the amount that would need to be added to the tank is very high. This would tend to pollute most tanks. Very few tanks are large enough to accommodate a filter feeder of this size. It is an animal that is best enjoyed in the ocean.
When stressed or sick, ophiuroids will autonomize their arms. Many people have reported brittle stars developing other injuries, like holes in the disk (probably from a predatory attack). If the damage is to a few arms, or a small hole in the disk, it is best to leave these animals in the tank and remove any animal that might be aggravating the 'star. Unexplained holes in the disk may be the result of ‘distended disk syndrome.’ (For examples, see the “outbreak” section of the Tabloids). The animal will very likely regrow the arms and repair the disk damage. However, if the brittlestar has lost more than half the disk, is staying out in the open, or unable to turn itself over when placed on its back, it should be removed and destroyed. It will not likely recover from extreme trauma. Euthanasia of echinoderms can be done through slow addition of fresh water or epsom salts until the animal no longer responds.
Brittlestars may hide out most of the time, but during the night the come out like janitorial crews! While they are excellent at finding bits of food in the rockwork, I recommend that large brittles be given some additional feedings with things like shrimp, squid, or fish. Spot feeding is a simple process, and you can use forceps, or a wooden skewer. When the “smell” the food in the water, they should come running! Just be careful of over stressing water quality!
Sea and Sky This has a lot of information on keeping aquaria. If you hunt through it and search their links, you may find some ophiuroid information.
Photolinks from About.com has a number of images of brittlestars and other echinoderms suitable for marine tanks, some with basic information and ordering information.
The John Rice Reef Page This is a really nice site by John Rice who has a spectacular reef aquarium. He has a lot of information, and under his Inverts link, some nice pictures and information on his success with brittlestars.
WetWebMedia has a nice informative page on brittlestars and seastars for your salt water aquarium.
Here are some great message boards to visit (I do!). Be sure to search the sites, and ask questions!
Reefcentral.com Forums (also with a main information site)
Reefs.org Forums (also with a main information site)
WARNING! Many fish will eat, or be eaten by, brittlestars
SPECIAL FEATURE: Map to the ‘Stars!!!