The blue starfish is a species of starfish that is well known for its bright blue color. They are also known as the Comet Sea Star, Blue Sea Star, or Blue Linckia Sea Star. It has a bright blue body that sometimes has white, red, or purple spots.Most are blue but some are orange, purple, or spotted with purple or red. When they are younger they are a different shade usually a green.
They are found in some aquariums as pets but do not usually survive very well. They have amazing regenerating abilities and can reproduce asexually. Their food habits vary from meat to bacteria.
The blue starfish gets its color from blue pigment (linckiacyanin) and some yellow pigment (carotenoids). The amount of each pigment makes the color of the blue starfish range from bright blue too orange. When it is younger it has a blue-green color, not the bright blue of the adult. It is firm to the touch, and has a central disc with five long thin arms coming off of it. It posses radial symmetry and can grow to be 12 inches in diameter. With a maximum arm width of approximately 40 cm.  It has a water vascular system for moving and eating. A water vascular system according to the Webster's New World College Dictionary is “in echinoderms, a system of closed tubes and ducts filled with sea water containing some protein, and functioning variously, as in locomotion, food gathering, clinging, and respiration”. 
During sexual reproduction, the blue starfish releases gametes freely into the water when it spawns. Usually they hold the substrate with the tips of their rays as they arch their body and spray either sperm or eggs into the water depending on their sex, blue starfish have separate sexes. If a male and female spawn near each other the fertilized eggs grow into larvae in a few days. The larva stays in the water column for 28-30 days, after that it will settle on a hard surface and metamorphosis into a mini adult. They often do not spawn in a home aquarium and have a long planktonic lifespan (free-floating larval stage), which makes them hard to raise at home. 
The blue starfish can reproduce asexually, but the details are unknown. During fragmentation, it can also regenerate a completely new starfish from just about any piece of its body that brakes off, when this happens the arm looks like a long stick with a star attached to the end - and are called comets. It doesn’t usually happen in a home aquarium though.  The blue starfish has a life span of up to ten years. 
The blue starfish is found in the Indian and Pacific ocean  near sunny reefs and reef fringes; it is usually found looking for food. The starfish is omnivore, which means it eats both animals and plants, it also eats waste. It averts its stomach while it feeds on coral. It eat small chunks of marine meat or clam for food and sometimes even bacterial films, small encrusting sponges, and dead mollusks. In a marine aquarium it prefers sandy, well lit or corral, rubble surface to attach to. Blue starfish often hide in coral or rocky crevices during the day. The blue starfish is solitary in the wild but it will tolerate other starfish and sociable fish in a marine aquarium. The blue starfish has means of protecting its self from attack. It has a chemical defense called saponin which is very effective in deterring predators. It shares this characteristic with the Crown of Thorns starfish. However this defense does not effect other animals, unless that animal is trying to eat the starfish. This however is not completely effective against all predators. For example, the dog-faced puffer is still able to eat the starfish. Some of its natural predators are puffer fishes, harlequin shrimp and sea anemones which are all invertebrates. In the wild it can be found with commensal starfish shrimp around its mouth or on the bottom of its arms. It is not tolerant of sudden changes in its oxygen level, or its salinity. Blue starfish is intolerant of copper-based medications and it must not be exposed to air if you handle it. The blue starfish is sometimes bothered by a parasitic gastropod or snail, Thyca crystalline. 
The blue starfish is often found in home aquariums but it does not usually live. One reason it often does not survive is they do not give it a long enough acclimation period or it was poorly shipped, which often happens. A good acclimation period is for a minimum of three to four hours. There are two ways of acclimating, the drip method and the cup method. Here is how you perform the cup method; first float the bag containing your starfish in it, in your tank to allow your new starfish to get used to the temperature of your tank. Then add a half cup every five minutes of water form your tank into the bag containing the starfish. Once your bag is full, dump half of the water down the drain and repeat the process. After your starfish is sufficiently acclimated remove it from the bag and place it in your tank. If you have a poorly shipped starfish, it may be in shock and may even begin to disintegrate within a few weeks of being shipped.
Another reason it may not survive is because it is put in a new tank so it has nothing to eat. If you put a blue starfish in a tank that is newer then six months, then it is unlikely to survive. The reason is they often reject food that is given to them; instead they go for bacterial film on the tanks glass. There for if you have just started a tank it is very unlikely that it will have the built up bacteria that the starfish would normally eat. 
Also it does not take well to medication in its tank. If you are medicating another fish in your take be sure that you remove your blue starfish first. they have been know to die from being exposed to copper-based medications, exposing it to air can also have the same effect. For example, the blue starfish should not be exposed to air while transferring it from different tanks because it can get air in its water vascular system. 
- Linckia by Wikispecies.
- Blue Starfish by Veterinary & Aquatic Services Department, Drs. Foster & Smith.
- Stars -- Linckia spp by Advanced Aquarist's Online Magazine, Rob Toonen.
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- BLUE STARFISH (Linckia laevigata): SPECIES ACCOUNTS by Animal Life Resource.
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- Blue Seastar(Linckia laevigata) by Scuba Equipment USA - Marine Species Gallery.
- Linckia laevigata by Wikipedia.
- water-vascular system by the Webster's New World College Dictionary.
- Blue Starfish by Practical Fishkeeping.