A brittle star is made up of an obvious central disk and five or six arms. The The nervous system consists of a main nerve ring which runs around the central disk. This rowing motion looks similar to the way a There are male and female brittle stars, although it is not obvious which sex a brittle star is without looking at its genitals, which are located inside its central disk. Brittle stars are mainly deposit feeders, scavengers, and plankton feeders; however, they sometimes trap sizable animals.
They have tube feet on their underside, like sea stars, but the feet do not have suction cups at the end and are not used for locomotion—they are used for feeding and to help the brittle star sense its environment. The brittle stars come out at night and scavenge all over the bottom of the tank and on the live rock looking for bits and pieces of things to eat. Nerves run down each arm. In modern forms, the vertebrae occur along the median of the arm. Brittle stars don't have an anus, so any wastes must come out through the mouth.Brittle stars can drop an arm when being attacked by a predator. There are 10 pouches in the stomach where the prey is digested. Brittle stars occupy many marine habitats, often at great depths. That is, the internal organs of digestion and reproduction never enter the arms, as they do in the Asteroidea. An esophagus and stomach connect to the mouth opening.Brittle stars feed on organic material on the sea floor (they are primarily detritivores or scavengers although some species occasionally feed on small invertebrate prey). This results in a free-swimming larva called an ophiopluteus, which eventually settles to the bottom and forms a brittle star shape.Some brittle star species may also reproduce asexually through a process called fission. The spines, in ophiuroids, compose a rigid border to the arm edges, whereas in euryalids they are transformed into downward-facing clubs or hooklets. These arms are supported by calcium carbonate plates (also known as vertebral ossicles).
The time period between successive divisions is 89 days, so theoretically, each brittle star can produce 15 new individuals during the course of a year.Brittle stars generally sexually mature in two to three years, become full grown in three to four years, and live up to 5 years.Brittle stars use their arms for locomotion. The most mobile of the echinoderms, brittle stars are able to "crawl around" by holding their central disc above the bottom as they move their arms forward. Like sea stars, brittle stars have a vascular system that uses water to control locomotion, respiration, and food and waste transportation, and their tube feet are filled with water. New arms begin to grow before the fission is complete, thus minimizing the time between possible successive divisions. 1995).
They come in colors of black, brown, and a combination of the two, sometimes having grey bands around some of their limbs. Basket stars feed on plankton and bacteria they catch by suspension feeding. Brittle stars feed on organic material on the sea floor (they are primarily detritivores or scavengers although some species occasionally feed on small invertebrate prey). They are not usually used for feeding, as in Asteroidea. Algal parasites such as Brittle stars are not used as food, though they are not toxic, because of their strong skeleton. In many species, larvae develop inside the body of the parent.When an arm is lost, brittle stars often regenerate the lost limb. Euryalids are similar to ophiurids, if larger, but their arms are forked and branched. In general sea stars are difficult to keep. Jennifer Kennedy, M.S., is an environmental educator specializing in marine life. The mouth opening is also used to expel waste. These sacs are located on the bottom of the central body disk.