Starfish are quite rare in Hawaiian water compared to other arts of the pacific. Hawaii is thousands of miles away from the mainland and some creatures just had a hard time making the long journey all the way to Hawaii back in time. Starfish (sea stars) are one of those creatures and only a few species live in Hawaii and it is a treat to see one.
The red velvet sea star does not have a specific Hawaiian name as before scuba divers came along they more then likely never saw one! The more general name for all starfish is hoku kai.
These starfish like to live in dark caves usually in depths from 20 to 80 feet deep where they are attach to the cave floor or walls with their five legs that have tube feet with suckers on the end.
Starfish are really weird creatures as they they have five body parts radiating from the center and a water filled body. Their hollow tube feet pump water through them to move like a hover craft.
The arms are flexible and their body parts are in their arms! This allows them to reproduce by detaching an arm which will grow into a whole new starfish!
The also reproduce but broadcasting sperm and eggs into the sea water that grow into larvae that can swim away and find a new place to settle onto the reef.
They also have a very strange way of feeding. In the middle of their body on the bottom side they have a mouth and a large stomach inside. When they find something they wish to eat like a sea urchin they can expel their stomach over their prey and digest the food outside of their body! One of the starfish species even eats coral by digesting the coral polyps while laying on top of the sharp coral.
A good place to find some of the starfish species in Hawaii is on rock jetties where they often congregate to breed. Along one jetty in Kauai I was diving and found little detached arms all over the rocks. It look like there had been a starfish massacre but I went back and dove there again two weeks later and all the arms were growing into whole new starfish!
You can see the hoku kai in action in my video, “The World’s Guide to Hawaiian Reef Creatures,” up on my underwater educational web page at www.underwater2web.com. You can also follow my marine life daily Instagram post at terry.lilley
Aloha from under the surf,
Terry Lilley, a marine biologist, lives in Hanalei. His websites include underwater-2web.com and www.gofundme.com/5urrm4zw