Sea Apples - Amazingly Colorful Sea Cucumbers!

Part 2 of our “Smorgasbord of Food Offerings from the Sea” series
By Janice Edwards

The handful of marine species commonly known as sea apples are not sea fruit, as advertised, but rather a type of sea vegetable, namely a sea cucumber. Sea cucumbers are the common name for a class of echinoderms known as holothuroideans. Sea apples have more of an apple shape whereas other sea cucumbers have, well, more of a cucumber-like shape.  Sea apples can get as big as 8 inches long. That’s one big apple!

Sea apples live on hard surfaces like the ocean floor and coral reefs. They can be found in parts of the East Indian and West Pacific Oceans.

Amazing fact #1: Sea apples come in all kinds of beautiful colors and are definitely the best-looking of the sea cucumber group. Body colors range from purple, blue, red, and orange. Additionally, they have a central mouth cavity which is ringed with feathery, colorful tentacles and they move around with rows of tube feet which can be yellow or red.
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Photo by I, Marrabbio2 [CC BY-SA 3.0, via Wikimedia Commons]

Photo by Alexander Vasenin (Own work) [ CC BY-SA 3.0, via Wikimedia Commons]

As filter feeders, they mainly eat plankton and commonly eat at night to protect their feathery tentacles from predators. During the day, they curl up into their protective, spherical-like shape.

Amazing Fact #2: Their tentacles are stuffed into their mouths and covered in mucus. Then they are waved around in the water and back into their mouths to scrape the plankton off.

So what do they do if a predator is  ready to take the proverbial bite out of the apple? Sea apples have options in the way of defense mechanisms: They can release a toxin into the water to deter their predator--apparently not very tasty stuff. They can also swell up to almost double their size by swallowing large amounts of water. This allows them to be moved quickly to a new environment by water currents--quicker than walking using tube feet! Or they can utilize another method which leads us to--

Amazing Fact #3: They can eject their insides as a distraction and diversion in order to escape. Ugh!
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​What do they contribute, you might ask? As filter feeders, they "clean up" the water and recycle nutrients back into the food web.

They are mainly caught for aquariums but are difficult to keep alive because of their feeding requirements - it is hard to keep them supplied with enough plankton and they can easily starve. Plus they don't get along with other creatures in the aquarium. (See previous comments about defense mechanisms.)

So how about some lightly sautéed, sliced sea apples to go with that grilled sea pork? Yum yum!