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Phylum Echinodermata > Class Stellaroida > Subclass Ophiuroidea
Brittle stars
Subclass Ophiuroidea
updated Apr 2020
if you learn only 3 things about them ...
Super stars of the echinoderms: they are the largest group of echinoderms, fastest moving, most nervous--falling apart easily.
Although numerous, they are shy and seldom seen.
Some live inside sponges and on other animals.

Where seen? Brittle stars are the most common echinoderms on our shores but are rarely seen as they shun the light and are more active at night. Often, all that can be seen of a brittle star are its skinny, spiny arms! Ones with longer arms may be seen hiding among coral rubble. Tiny ones shelter under rocks, beneath the sand and in even on other animals such as sponges.

What are brittle stars? Brittle stars belong to Phylum Echinodermata and Subclass Ophiuroidea which has about 2,100 known species. This makes Ophiuroidea the largest group of echinoderms. About 300 brittle star species are found in shallow tropical waters.

Basket case: Included in Class Ophiuroidea are the basket stars (Suborder Euryalina) that have branched arms and thus appear basket-like. Large ones are generally found in deeper water, although small ones have been encountered on the intertidal.

Features: Brittle stars are related to sea stars but belong to a different class and have somewhat different features and habits. Like other echinoderms, brittle stars are symmetrical along five axes, have spiny skin and tube feet.

An armful:
A brittle star is almost all arms. Its central disk is usually only a few centimeters wide while its thin, flexible arms can be very long. The arms are made up of large, well developed ossicles (plates made mostly of calcium carbonate). The ossicles are connected together like a vertebrate with ball-and-socket joints. A brittle star lengthens its arms by adding ossicles where the arm joins the central disk.

Sometimes confused with
bristleworms. Here's more on how to tell them apart. Feather stars may also appear similar but they usually have 10 or more arms.

What do they eat? Many brittle stars feed on detritus, using their arms to gather this from the surface or to filter these out of the water. Unlike sea stars, a brittle star doesn't have a groove on the underside of its arms.

Brittle stars have only one opening on their underside that functions as both a mouth and anus! Unlike sea stars, the digestive system of brittle stars doesn't extend into their arms. A brittle star's mouth is surrounded by jaws made up of a circle of five large toothed plates that meet in the middle. Unlike sea urchins, the jaws cannot be extended outwards.

Tiny tube feet emerge from holes between the ossicles in the arms. These may 'wipe off' food particles stuck on the hooked or mucous-coated spines, or collect particles off the surface, and pass these on to the central mouth. Other brittle stars are carnivores that use their arms to sweep tiny creatures to their mouths. Yet others are scavengers, nibbling on their food with their jaws or using the tube feet near their mouth. Some brittle stars use their tube feet to sense chemicals released by their food.

Often all that is seen of a brittle star are
its arms sticking out of a hiding place.
Changi, Jan 04

Underside of a Blue lined brittle star.
Chek Jawa, Aug 05

Close up of tubefeet on arms
Pulau Sekudu, Jun 06
Falling apart: As its name suggests, a brittle star has a tendency to fall apart. It may purposely throw off an arm when threatened. So please don't handle brittle stars.

The dropped arm may continue to wriggle to distract the predator while the brittle star escapes. The brittle star is able to do this because the ossicles in its arms are connected by mutable connective tissue. The brittle star can rapidly change the consistency of this tissue from rock hard to almost liquid. The arm eventually re-grows, but it can take months before it is fully restored.

Brittle star babies: Most brittle stars have separate genders and are usually either male or female. Sperm or eggs are stored in pouch-like chambers in the central disk. These are usually released simultaneously into the water. This usually happens at night. Some spawning brittle stars assume a push-up posture, raising the central disk into the water currents by standing on the tips of their arms.

Brittle stars undergo metamorphosis and their larvae look nothing like their adults. The form that first hatches from the eggs are bilaterally symmetrical and free-swimming, drifting with the plankton. They eventually settle down and develop into tiny brittle stars. Some brittle stars brood their eggs.

A Blue lined brittle star possibly releasing eggs
Pulau Sekudu, Jul 04

Basket start on a Flowery soft coral.
Beting Bronok, Jul 13.

Sometimes seen in large numbers.
Chek Jawa, Aug 07
Star-spangled sponges: Tiny brittle stars (1-2cm with arms) often live inside sponges. Look closely at the holes of a sponge and you might see their little arms sticking out. They may also be found living with corals and even other echinoderms. One tiny brittle star Ophiosphaera insignis lives near the mouth of the sea urchin Diadema setosum. Here, the brittle star finds safety and food that is gathered by the sea urchin. Another tiny brittle star Ophiomaza cacaotica shelters near the mouth of feather stars. Yet others cling to the branches of gorgonians.

Stars come out at night: Brittle stars are plentiful but seldom seen. They have many predators, so brittle stars usually only come out at night. Creatures that snack on brittle stars include fish, crabs, hermit crabs, mantis shrimp and even sea stars and other brittle stars.

This brittle star lives only in feather stars!
Raffles Lighthouse, Jul 06

Tiny colourful brittle stars
may live on a variety of other animals.
East Coast Park, Jun 06

Tiny in-a-sponge brittle stars live in this sponge.
Pulau Sekudu, Jul 05
Speedy stars: Brittle stars are the fastest-moving echinoderms! While sea stars use their tube feet to move slowly, brittle stars use their highly flexible, spiny arms instead. Their arms move in a snaky manner, 'Ophiuroidea' means 'snake-like'.

To move, a brittle star generally gets a grip on something with one or two spiny arms. These then pull while the remaining arms push or trail behind. Some brittle stars may also 'swim' by vigorously rowing their highly flexible arms, similar to the breast-stroke!

Human uses: Brittle stars are not used for human purposes.
Flat-armed brittle star

Brittle stars on Singapore shores

Other unidentified brittle stars on Singapore shores

Beting Bemban Besar, Jul 20
Photo shared by Vincent Choo on facebook.


Order Ophiuroidea recorded for Singapore
Fujita T. & Irimura S. Preliminary list of ophiuroids (Echinodermata: Ophiuroidea) collected from the Johor Straits,
in red are those listed among the threatened animals of Singapore from Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened plants and animals of Singapore.
from WORMS.

  Brittle stars seen awaiting identification
Brittle stars
can only be positively identified from microscopic examination of their internal parts and are thus difficult to distinguish in the field. On this website, unidentified brittle stars seen are grouped by general colour and pattern for convenience of display.
  Bottlebrush brittle star
Flat-armed brittle star

Ghost brittle star

  Family Amphiuridae
  Amphioplus (Amphioplus) lucidus

Amphioplus (Lymanella) andreae
Amphioplus (Lymanella) depressus

Amphipholis misera

Amphiura (Amphiura) duncani
Amphiura (Amphiura) instans

Amphiura (Ophiopeltis) phalerata

Dougaloplus echinatus

Ophiocentrus dilatata
Ophiosphaera insignis

  Family Ophiactidae
  Ophiactis delagoa
Ophiactis macrolepidota
Ophiactis modesta
Ophiactis savignyi
[=Ophiactis versicolor, Ophiactis maculosa] (Tiny in-a-sponge brittle star)
Ophiactis picteti [= Ophiactis sinensis]

  Family Ophiocomidae
  Ophiarthrum elegans

Ophiopsila pantherina
Ophiopsila sp.

  Family Ophiodermatidae
  Ophiarachnella gorgonia

Ophioconis permixta

Ophiodyscrita instrata

  Family Ophiolepididae

Ophiolepis cincta cincta
Ophiolepis nodosa
Ophiolepis superba

  Family Ophionereididae
  Ophionereis dubia

  Family Ophiotrichidae
  Macrophiothrix demessa
Macrophiothrix fumaria= Ophiothrix (Placophiothrix) fumaria
Macrophiothrix galatheae
Macrophiothrix hybrida=Ophiothrix (Placophiothrix) lineocaerulea
(Blue-lined brittle star)
Macrophiothrix longipeda=Ophiothrix longipeda
(Very long-armed brittle star)
Macrophiothrix lorioli
Macrophiothrix melanosticta=Ophiothrix (Placophiothrix) melanosticta
Macrophiothrix nereidina=Ophiothrix (Keystonia) nereidina
(Violet brittle star)
Macrophiothrix propinqua=Ophiothrix propinqua
Macrophiothrix robillardi

Ophiocnemis marmorata

Ophiomaza cacaotica
(Feather-hitching brittle star)

Ophiothela danae
(Tiny colourful brittle star)
Ophiothela venusta

Ophiothrix sp
(Upsidedown brittle star)

Ophiothrix (Acanthophiothrix) leucotrigona
Ophiothrix (Acanthophiothrix) spinosissima
Ophiothrix (Ophiothrix) ciliaris
Ophiothrix (Ophiothrix) exigua
Ophiothrix (Ophiothrix) miles
Ophiothrix sp.

  Family Ophiuridae
  Ophiura kinbergi
Ophiura pteracantha

  Family Euryalidae (Basket star)
(formerly Family Gorgonocephalidae)
  Euryale aspersa (DD: EN? Data deficient, possibly Endangered)

Links References
  • T. Fujita. 29 June 2016. Brittle stars of Ophiodermatidae and Ophiolepididae (Echinodermata: Ophiuroidea: Ophiurida: Ophiurina) collected from the Singapore Strait. The Raffles Bulletin of Zoology 2016 Supplement No. 34 (Part I of II) Pp. 619-626.
  • Fujita T. & Irimura S. Preliminary list of ophiuroids (Echinodermata: Ophiuroidea) collected from the Johor Straits, Singapore. 10 July 2015. The Comprehensive Marine Biodiversity Survey: Johor Straits International Workshop (2012) The Raffles Bulletin of Zoology Supplement No. 31, Pp. 264-272.
  • T. Fujita. 29 June 2016. Brittle stars of Ophiodermatidae and Ophiolepididae (Echinodermata: Ophiuroidea: Ophiurida: Ophiurina) collected from the Singapore Strait. The Raffles Bulletin of Zoology Supplement No. 34: 619–626 Pp. 619-626. [pdf]
  • Lane, David J.W. and Didier Vandenspiegel. 2003. A Guide to Sea Stars and Other Echinoderms of Singapore. Singapore Science Centre. 187pp.
  • Chou, L. M., 1998. A Guide to the Coral Reef Life of Singapore. Singapore Science Centre. 128 pages.
  • Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened plants and animals of Singapore. Nature Society (Singapore). 285 pp.
  • Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore. National Council on the Environment. 163pp.
  • Gosliner, Terrence M., David W. Behrens and Gary C. Williams. 1996. Coral Reef Animals of the Indo-Pacific: Animal life from Africa to Hawaii exclusive of the vertebrates Sea Challengers. 314pp.
  • Allen, Gerald R and Roger Steene. 2002. Indo-Pacific Coral Reef Field Guide. Tropical Reef Research. 378pp.
  • Edward E. Ruppert, Richard S. Fox, Robert D. Barnes. 2004.Invertebrate Zoology Brooks/Cole of Thomson Learning Inc., 7th Edition. pp. 963
  • Pechenik, Jan A., 2005. Biology of the Invertebrates. 5th edition. McGraw-Hill Book Co., Singapore. 578 pp.
  • Hendler, Gordon, John E. Miller, David L. Pawson and Porter M. Kier, 1995. Sea Stars, Sea Urchins, and Allies: Echinoderms of Florida and the Caribbean. Smithsonian Institution Press. 390 pp.
  • Schoppe, Sabine, 2000. Echinoderms of the Philippines: A guide to common shallow water sea stars, brittle stars, sea urchins, sea cucumbers and feather stars. Times Edition, Singapore. 144 pp.
  • Coleman, Neville. undated. Sea Stars of Australasia and their relatives. Neville Coleman's World of Water, Australia. 64pp.
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