Sea cucumbers (loli) are a common sight on Hawaiʻi’s reefs. This unique and strange animal has a distinct tubular shape which some say resembles sausages. Sea cucumbers use the tube feet that cover their bodies to help them move through the reef and are also closely related to sea stars and sea urchins. However, unlike their relatives, sea cucumbers’ five-part radial symmetry is not as obvious due to their internal structure.
Most sea cucumbers feed upon organic matter in the sand. With a sweeping action, they intake sand or sediment with their feeding appendages and digest all organic matter, excreting the remnants in strands and piles of sand. Although they excrete waste through their anus, it is also is a means of respiration for this quirky creature. Water is drawn in through the anus and then expelled, reaching an organ called “respiratory trees,” where oxygen is extracted.
Sea cucumbers have a couple of ways to defend themselves. Many have the ability to auto-eviscerate or eject all internal organs through their anus. This tactic is believed to sidetrack the predator while the sea cucumber escapes. Depending on species, regeneration can take a few months, and the sea cucumber loses its ability to feed until they’ve fully healed. An alternate means of protection is expelling toxic white threads called cuvierian tubules that can shock and entangle a predator. These defense mechanisms can come in handy for an animal that lacks the ability to flee predators rapidly.
Sea cucumbers, like most echinoderms, reproduce by releasing sperm and eggs into the water. After a planktonic stage, larval will settle and mature. Many spawning events have been observed on Hawaiian reefs, typically during high tide on a full moon, as members of the same species will be seen gathering and emitting milky games through a pore near the mouth.
*Due to the constant rotation of animals back to the ocean, we cannot guarantee the presence of any specific animal.