At the Aquarium
This species is not currently on exhibit at the Aquarium.
Northeast Pacific Ocean.
Benthic dwellers, this sea cucumber species lives on the sandy seafloor at depths of 30-400 meters (100-1300 feet)
Johnsons sea cucumber, an echinoderm, has a long, tube-like, almost cylindrical soft body which like its echinoderm relatives, sea stars, sea urchins, and sand dollars, exhibits five-part symmetry. However, instead of the rigid test (endoskeleton) of other echinoderms, the ossicles (calcareous plates) of this sea cucumber’s skeleton are small and widely spaced. Its mouth is surrounded by small tentacles tipped with fine cilia. The body of a Johnsons sea cucumber is bright orange to red in color, accented by white tentacles and tube feet.
Sea cucumbers do not have a brain, heart, or lungs. Instead of a central nervous system, they have a nerve ring with radial nerves, along with a nerve net within the skin that can detect chemicals and touch.
To 40 cm (16 in) long
Sea cucumbers feed by processing detritus gathered by filtering the seafloor sand and mud sediments. In addition to plant and animal remains, Johnsons sea cucumber may also process small live prey. Sand is taken into the mouth, sifted, and expelled. Food particles are retained.
Sexes are separate in most sea cucumbers. Eggs or sperm are broadcast into the water column where external fertilization occurs. The embryonic and larval growth of a sea cucumber may be quite slow, making it difficult for sea cucumbers to repopulate or recover after a reduction in population.
Little is known about the behavior of Johnsons sea cucumbers in the wild. They move by using their tube feet to inch along the sea floor while flexing their tube-like bodies back and forth through the water. Living in the benthic zone, Johnsons sea cucumber inches along the seafloor as needed to find food or escape predation.
These sea cucumbers absorb oxygen by forcing water through hollow, branched organs called respiratory trees. This requires the sea cucumbers to rapidly process large amounts of water that is taken in and expels through the anus.
As is common among sea cucumbers, a Johnsons sea cucumber can shed its internal organs, (self-eviscerate), to escape predators. The shed organs may confuse, entangle, or distract a predator by providing a convenient snack and give the sea cucumber a chance to escape. After such an event, a sea cucumber will find a safe place to hide while its internal organs grow back.
A sea cucumber has a very flexible body structure that gives it the ability to fit through small crevices. It can loosen a substance under the skin called catch collagen that forms its body wall. As a result, its body becomes almost liquid in nature. It can then tighten the structure of its cells to again firm its body.
Although this species is not currently harvested commercially for ethnic seafood, other species of sea cucumbers in the genus Parastichopus, including the California sea cucumber (P. californicus) are in danger of being overharvesting. Many sea cucumber species have already been significantly reduced in numbers. Sea cucumber species’ slow embryonic and larval growth rates only increase the dangers posed by over harvesting.
Sea cucumbers are vulnerable to ocean pollution because, as filter feeders, they ingest plastic particles that drift to the seafloor as marine snow.
The California sea cucumber, P. californicus, is known as a bipolar feeder. It is able to take in food from its mouth and is also capable of taking in food from its anus.