Sea Cucumbers Change from Solid to Liquid and Back Again

Image: Jacinta Richardson and Paul Fenwick, Wikimedia Commons

These incredible, ground-feeding marine animals have the extraordinary ability to transform their bodies into different states of matter.

Sea cucumbers are echinoderms with elongated round bodies varying in size from 2 centimeters to 2 meters, containing a set of feeding tentacles at one end. These organisms are found worldwide and serve as the earthworms of the sea, performing a vital role in the marine ecosystem. They use their tentacles to feed on dead organic matter and correspondingly serve as biomass recyclers of the ocean floor. The process is performed by an uptake of floor debris and inner filtering mechanism that passes the cleaned material out of the animal’s other end.

These echinoderms possess an internal support structure similar to fish, composed of calcified structures which makes them rigid. The most amazing feature of these sea creatures’ hard, spiky bodies lies beneath the skin within this endoskeleton.

Image: Ed Bierman, Flickr
Image: Ed Bierman, Flickr

Sea cucumbers have the innate ability to transform their spinal processes from solid to liquid states of matter, leading to scientists to conclude their entire bodies are able to undergo neurologically controlled and reversible conversions.

The transformation can be attributed to unique fibers spanning collagen, the specific tissue component that changes from solid to liquid states. This behavior allows sea cucumbers to perform unique physical maneuvers including hiding in small spaces to escape predators. 


An animal’s ability to change states of matter is a revolutionary discovery, opening the door to a world of future possibilities within the realm of human application.

Despite bans on the fishing of sea cucumbers, their populations are currently threatened by the illegal activities of poachers.