Shape-Changing Sea Cucumbers

Rockaway Beach, Bainbridge Island, WA – It was just one bright flash of orange thinly veiled by buoyant seaweed rising and falling with the lapping tide. In the marine environment of blue grays and mottled greens and browns, bright colors usually mean something vibrantly alive, something worth investigating. In this case, I had to wade deeper and hope that I could reach the mysterious curiosity without filling my boots with saltwater.

IMG_7701Luckily for me, I found a stunning orange sea cucumber and kept my feet dry too. I was able to watch the sea cucumber hang on the underside of a beach boulder while reaching out tiny tentacles to catch food.

Sea cucumbers look and feel soft and squishy, due to their special skin, (mutable connective tissues) which gives them the ability to quickly push water out of their bodies to become harder and firmer. This nifty shrinking trick helps them wedge into small crevices then expand to increase their gripping power. What other creature can literally change from relatively solid to a puddle of gel in a matter of minutes? Scientists have only recently begun to understand the extraordinary skin design found in these creatures and hope to develop new medical bio-materials that function in a similar way. Science Explorer, 2016

But…that’s not the only stunt the sea cucumber is capable of. The next strategy description is only for those with strong stomachs. This soft-bodied creature is easy to catch and eat, so have a wide variety of predators, including crabs, sea stars, fish and even humans. To escape from predators, they can spew their intestines and other internal parts out their back-end into the face of their pursuer, startling them and perhaps giving them something to eat while the sea cucumber glides away.

Interestingly, the sea cucumber will regrow the lost parts and have been known to deliberately eject them during winter, possibly to conserve energy. The sea cucumber’s body is like a long water balloon with openings on each end. Some sea creatures use the cucumber as a refuge by entering its watery body through the anus and living inside. Kind of gross, but very effective.


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Every creature has an unique story of design and function as a part of the environment in which they live. The orange sea cucumber is no exception. When you track wonder, be aware of unusual colors, patterns or textures. They are often subtle clues leading to amazing discoveries.

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Orange Sea Cucumber
Sea Cucumbers can push water out of their bodies, becoming small and dense

When and Where – Sea cucumbers are very common in the quiet waters of the Salish Sea. Watch for the bright flash of orange or red in the cobble and rocky areas of the low intertidal zone. The Orange Sea Cucumber uses tube feet to cling to rocks and feeds with extended tentacles on the other end. Rows of beaded dots line their bodies. Occasionally, you may find sea cumbers compacted into a short dense “pickle” shape.

When touching a marine animal, especially those with soft bodies, always wet your hands with sea water first to help preserve the animal’s protective slime coat. Another good rule to follow is the 1 or 2 finger touch rule to minimize contact with delicate tissues.

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Wonder Triggers for Young Trackers

What colors do you see in the intertidal zone? What colors are the most common? As you explore, watch for uncommon colors.

Sea cucumbers are fun to find. They protect themselves by hiding so think about the best places to hide.  Check the underside of large beach boulders or places where a rock has cracks or crevices next to other rocks. If you find one sea cucumber, there are often more in the area. Why do you think there would be more? What causes animals to stay in a specific place? (usually good food sources and lack of predators)

Use one finger to gently touch the outside of the sea cucumber. What happened?

References and Resources

Friends of Skagit Beaches

Pets on Mom

Advanced Aquarist

Images – SPegany, ©2018

One thought on “Shape-Changing Sea Cucumbers

  1. Very interesting sea creatures. Who would guess all of the God given qualities they possess? Thanks Wonder Tracker!


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