The first time I saw a five inch long spotted linckia sea star while diving, I gently picked it up to get a better view and shoot a video clip of this beautiful red and grey reef creature. While the star was in my hand it’s arm fell off! I immediately felt bad and though I might have killed the poor animal by disturbing it. I later found out that this species of sea star loses its arms all the time and this is a natural process.
Most sea stars have five arms and if one of them is removed by a predator a new arm will grow back. Many animal species can regenerate limbs, like the octopus or a lizard’s tail but the linckia sea star is special because it can regenerate the limb it lost and the severed arm will grow into a brand new starfish! This is actually the way this starfish can reproduce and populate the coral reef.
This is an amazing adaptation because reproduction often takes time when males and females have to mate but with the linckia sea star reproduction happens almost immediately. If the conditions out on the reef are healthy for the sea stars and there is lots of food available the star can drop off several arms producing offspring quickly to populate the area. It only takes a few weeks for the severed arm to grow into a whole new complet sea star with five arms and for the original sea star to grow back its arms it lost. Within a few weeks one sea star turns into three sea stars!
The spotted linckia comes in many different colors. Some are solid grey with brown spots and others are almost solid red with grey spots. It is easy to tell if the sea stars are related because if an adult is grey with red spots, when it drops off an arm the new star that grows will be grey with red spots just like the adult that lost its arm.
The linckia sea star likes to live in shallow calm water where it feeds on algae that grows on the lava reef and the best place to find them is in calm lagoons or on the inside of rock jetties. They tend to hang out together so when you find one often you can find a dozen in the same area.
You can see the spotted linckia sea star in action in my movie The Worlds Guide To Hawaiian Reef Creatures that will be up online soon on my underwater educational web at www.underwater2web.com.
Terry Lilley is a marine biologist who lives in Hanalei, and is a co-founder of Reef Guardians Hawaii, a non-profit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawaii please visit www.reefguardianshawaii.org.