Updated: Aug 23, 2021
Have you ever thought about how difficult it is to find the color blue in nature? This is because a true blue color or pigment is very rare, especially in animals. In the case of species like the blue jay and the blue morpho butterfly, their blue coloration comes from structural effects, like iridescence and selective reflection.
The blue sea star "is one of the few blue animals whose coloration is caused by a pigment rather than by structural coloration. The species produces a carotenoprotein known as linckiacyanin, which is made up of multiple different carotenoids, giving the sea star its distinctive blue color."
The blue sea star, or blue starfish, has the scientific name Linckia laevigata. It has five cylindrical arms of fully rounded termination, meaning its arms have rounded tips. Furthermore, each arm has an eye at each end, although, their eyes are only able to detect light and darkness. Their coloration ranges from lighter blues to darker tones, occasionally with dark spots. Contrary to their name, there are color variants of the blue sea star ranging from bright blue to green, pink, or yellow.
Populations of the blue sea star are most commonly found in shallow tropical waters of around 60 meters near coral reefs or seagrass beds. They can be found throughout the Indo-Pacific region from eastern Africa to Hawaii, the South Pacific Islands, Australia, Thailand, and Japan, and are difficult to spot elsewhere.
Life Cycle and Reproduction
Blue sea stars, like most other sea stars, form groups when it is mating season, typically during the summer, in order to increase the chances of fertilization.
"During the mating process, the gametes are released into the water, getting developed in a few days to become in larvae. In about 30 days larvae become tiny blue starfish, very similar to an adult but much smaller."
This species is known to live up to ten years in their natural habitat, but this number decreases in a big proportion when they are in captivity, as their tolerance range is quite narrow, meaning they require precise habitat conditions for their survival.
The blue sea star is omnivorous and its diet includes a variety of other animals like mollusks, worms, detritus, and each other! It is predominantly a scavenger, so it prefers dead organisms within the coral reef and on rocks, but occasionally feeds on plants like algae, and other microbes. When the blue sea star eats, it sits on top of the food and pushes its stomach out through its mouth to cover the food and digest it externally. It is quite fascinating!
Although the tolerance range for the blue sea star is limited, as aforementioned, the species is often kept in aquariums because of their beauty.
Interestingly, the blue starfish are being tested as a potential source of anti-tumor and antibacterial agents.
Sea stars move very slowly. They use a water vascular system that uses water pressure to create a network of tube feet that look like hundreds of tiny, hydraulically operated legs.
They are able to regenerate their arms in case they are damaged or lost to predators including various pufferfishes, Charonia species (triton shells), harlequin shrimp, and even some sea anemones.
Blue sea stars generally live solitary lives; they hide on rocks during the day and are more active during the night.
The blue starfish have saponins which are toxic steroids that are used as a defense mechanism against predators.