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CRITTER: Meet the Lumahai Cave Sponge and Gargonians

If you have ever driven a car from Hanalei Bay in Kaua‘i to Ke‘e Beach you have driven right over underwater caves that are just packed full of amazing colorful creatures! Kaua‘i’s North Shore has giant surf in the winter that crashes onto the lava cliffs carving caves.

Some of the caves at Lumaha‘i Beach go all the way back under the road up above! In the summertime when the surf is small we scuba dive into these caves and found them as colorful as the most-beautiful artwork you have ever seen.

One might think the underwater caves and lava tube would be dark and black, but it is just the opposite. These caves get very little sunlight, so you need bright underwater flashlights to safely enter the caves. When you shine your light on the cave walls you are just stunned by the colors. The walls are solid green, blue, red, yellow, black and white. What you are looking at are sponges that get their bright colors by absorbing dissolved minerals in the sea that come from volcanic rock when it breaks down over millions of years.

Your grandparents may have used natural sponges to clean their kitchens, and there is a reason for this. The sponges that grow in the sea are about the most absorbent natural products ever discovered. Sponges suck in vast amounts of salt water and filter out food and toxins then expel perfectly clean sea water. The coating of sponges in the submarine caves act as a giant filter for the ocean. When the waves surge back into these caves the sponges on the cave walls filter and clean the surf.

Sponges live under piers, back in caves and other dark parts of the coral reef, and for some reason they are not affected by pollution. They are nature’s natural filtering system, and they can filter polluted water and live when other sea creatures would die.

Also growing in the sponge-filled Lumaha‘i caves are small, five-inch-tall gorgonians. These red or yellow creatures look like little trees, and they also filter the seawater with their tiny, stinging polyps. Gorgonians are common throughout the Pacific Ocean but super-rare in Hawai‘i. The Lumaha‘i caves are the only dive site I have ever seen them growing in.

You can learn all about the giant waves at Lumaha‘i that carve these amazing and colorful caves in my new movie, and also get an underwater tour of the caves at

You can see all kinds of marine sponges up on my web at, as I have sponge movies from all around the world, and many of them are the most colorful creatures in the sea!


Terry Lilley is a marine biologist living in Hanalei and co-founder of Reef Guardians Hawai‘i, a nonprofit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawai‘i go to
Source: The Garden Island

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