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Related FAQs: Green
Brittlestars, Brittle & Basket
Stars, Brittlestars 2, Brittlestars
3, Brittlestar ID,
Brittlestar ID 2,
Brittlestar ID 3 & Brittlestar
Behavior, Brittlestar Compatibility, Brittlestar
Selection, Brittlestar Systems, Brittlestar
Feeding, Brittlestar Reproduction, Brittlestar
Disease, Brittlestar Disease 2,
Sea Stars,
Seastar ID 1, Seastar Selection, Seastar
Compatibility, Seastar Systems, Seastar
Feeding, Seastar
Disease, Seastar Disease 2, Seastar Reproduction,
Related Articles: Echinoderms,
An Introduction to the
Echinoderms: The Sea Stars, Sea Urchins, Sea Cucumbers and
More... By James W. Fatherree, M.Sc.
Sea
Stars, Crown
of Thorns Seastars, Marine Scavengers,
Brittle and Basket Stars, Class Ophiuroidea
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by Bob Fenner
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Astrophyton muricatum
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Brittle/Serpent and Basket Stars.
The Brittle or
Serpent Stars are grouped as the Class Ophiuroidea, characterized by
having highly mobile arms that can be used to assist in (relatively) rapid
motion. These starfish-like echinoderms are decidedly quicker and more
delicate than asteroids. Their common name is derived from their sinuous,
snake-like movements, and the fact that they're truly brittle and break
away easily if they come under attack. The podia in this class are
generally used as sensory organs, rather than for active feeding as with
their kin, the asteroids. There are more than 2,000 described species
worldwide, and they're found congregating throughout shallow reef
environments, hiding under rocks and within and between other living
organisms.
| Seemingly on the other end of the machismo scale are
the Brittle or Serpent Stars, which are so retiring and nocturnal that you
may never see them in your system. In the world's reefs, they are
everywhere. Two examples showing ophiuroids tell-tale arms coming out and
over soft coral in Bunaken, Indonesia, and a sponge in the Fiji. |
 
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Many reef aquarists have grown fond of them, as they
diligently work the underside and unseen recesses of the captive reef, scurrying
around under the ledges and rocks, eating detritus. They can play an important
role in keeping inaccessible areas of your tank cleaned up, and they stir up and
aerate the sand bed where the aquarist can't reach.
| They are literally and actually everywhere in marine
environments. If you look closely, especially by dark of night, you will
find ophiuroids lurking and feeding about. Here are some Brittlestar arms
sampling the mud about its borrowed hole/home in shallow water muck in N.
Sulawesi. |
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Beware the Midnight Fish Eater!
| One species in common use warrants a statutory warning.
This is the Green Brittle Star of the genus Ophiarachna. This animal is a
predatory fish eater, that does indeed do a spiffy janitorial job when small...
but grows quickly, and under darkness of night can/does learn to eat aquarium
fishes. This species has been documented to arch up in "sleeping
caves" of captive fishes and drop down on unsuspecting meals. If you use
this species, keep an eye on it, and a count on your piscine livestock. |
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Green Brittle Stars at a wholesalers. This is one way to
keep them from eating your fishes! |
A foot wide individual on the prowl! |
A retailers tank that has just had some
fish-food water applied to it. |
For the appropriately small Brittle/Serpent Star species,
selection is simple, placing healthy individuals at about one per ten gallons of
your systems capacity. You may be fortunate to "inherit" your Brittle
Stars with live rock, or collect them. For those near or traveling to the
tropical west Atlantic, the genera Ophionereis, Ophioderma and Ophiocoma
can be found in good numbers intertidally by carefully lifting rocks and using a
handnet to collect a few. Of course, you'll need to study up and prepare for the
captives intermediate needs, as well as comply with local ordinances, licensing.
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Ophioderma ensiferum, the Gaudy Brittle Star, in
an aquarium. |
Ophioderma rubicundum, the Ruby
Brittle Star in St. Lucia out at night. |
A whole tank of Ruby Brittle Stars awaiting
shipping at a L.A. wholesaler's. |
Some Brittlestar Species:
| Ophiocoma alexandri Lyman 1860, Alexander's Brittle
Star. Indo-Pacific. Disc size to 0.9 in., arms to 7.1 inches in length. Feed
on detritus both day and night by extending their arms from crevices,
beneath rocks. Southern California to Peru, including the Galapagos Islands.
Galapagos pic. |
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| Ophiocoma erinaceus Muller & Troschel 1842, the Spiny Brittle Star.
Indo-Pacific. To 5.5 inches in diameter. Dark by day, grayish bands by
night. Found in association with living corals. Hawai'i' pic at night. |
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| Ophiocoma paucigranulata, the Spiny Brittle Star.
Tropical West Atlantic. 4-6 inches in diameter. Have pale colored arms in
their middles. Found in association with living corals. Cozumel image at
night. |
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| Ophiomastix variabilis Koehler 1905. Black bodied
with long arms. All intermittently marked with yellow. Arms bear some
paddle like structures as modified spines. Found on living corals in
shallow water. Indo-West Pacific; Mozambique to Noumea. N. Sulawesi
pic. |
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| Ophiotheia danae (Verrill 1869). Order Ophiurae,
family Ophiotrichidae. Indo-West Pacific; Red Sea, eastern Africa to the
South Pacific, Japan. Narrow armed sponges, gorgonians and soft corals are
substrates for this diminutive Brittle Star. Banded arms come in blues,
orange, red, yellow. This image made in Pulau Redang, Malaysia on a
sponge. |
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| Ophiothrix purpurea Martens 1867. Reddish disk,
alternating colors on arms, with a distinctive black stripe running down
the middle of each one, surrounded by yellow. Fiji image. |
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| Ophiothrix suensonii, the Sponge Brittle Star.
Tropical West Atlantic. 2 1/2- 3 1/2". Live principally on sponges.
Also found on fire coral and gorgonians. Arms bear a dark line running
down their mid-line. Cozumel pix. |
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| Ophiothrix sp. 2. Similar to O. purpurea, but
with maroon spots in the middle of leg segments. Indonesia. Here climbing
over a toadstool soft coral at night in N. Sulawesi. |
 
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Basket Stars:
One fast mention of the bizarre Basket Stars. Though some
folks have reported reasonable success in their husbandry (see references
below), these nocturnal animals are by no means easy to keep in captive
conditions. They require specialized, large facilities, and diligence in their
food preparation and administration.
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| The Basket Star Astrophyton muricatum
in the Bahamas. Here "sleeping" by day on a gorgonian. |
The same species in a typical daytime spot;
curled up inside a brown sponge. This one in Belize. |
Night time, and it's time to unfurl your arms
into the incoming current and strain out your meal. Here in St. Lucia. |
Bibliography/Further Reading:
http://home.att.net/~ophiuroid
Damone, Joe. 1999. The Caribbean Basket Starfish (Astrophyton muricatum)
in the home aquarium: is it possible? Aquarium Frontiers Online 2/99.
Volkart, Bill. 1989. The beautiful Brittlestars. TFH 1/89.
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