Sea urchins and starfish are also members of the larger animal class known as echinoderms, which also include sea cucumbers. Their body is shaped like a cucumber, but they have tiny, tube-like feet that resemble tentacles and are utilized for both mobility and feeding.
One way sea cucumbers can trick or hurt predators is by launching their own poisonous internal organs out of their bodies in the direction of a potential foe. The organs regenerate, which would prevent them from being eaten. According to the species, sea cucumbers can range in size from less than an inch (2.5 centimeters) to more than six feet (1.8 meters).
What Do Sea Cucumbers Eat?
The critters use the extra 20 to 30 tiny tube feet around their mouths to shovel everything in, even sand, as they slowly meander around. According to the National Oceanic and Atmospheric Administration (NOAA), their main food sources are minute fragments of algae and marine life, which are gradually broken down into smaller and smaller pieces, much like how earthworms break down organic waste in gardens.
The sea cucumbers’ intake of sand goes through their entire system without any interruption and exits as a sandy poop log. Sea cucumbers emit chemicals that help ocean ecosystems, notably coral reefs, in addition to sand. The natural digesting process of sea cucumbers results in waste products with a relatively high (or basic) pH, which means the water surrounding sea cucumber habitats is partially shielded from ocean acidification, according to a 2011 study published in the Journal of Geophysical Research.
Additionally, calcium carbonate, a key component of coral production, and ammonia, a nutrient that encourages coral growth, are excreted by sea cucumbers.
The digestive, respiratory, and reproductive systems are the three main divisions of the sea cucumber’s very straightforward internal structure.
Despite the fact that sea cucumbers lack bones, several species of the animal have a simple skeleton consisting of microscopic calcium carbonate plates that are strewn around loosely beneath the skin, according to UCMP. According to the University of Alaska Southeast, several species have the ability to align their bone plates in order to make their bodies rigid when in danger.
Between the mouth and the anus, the digestive tract is made up of a long intestine that is around twice to three times as long as a sea cucumber. Sea cucumbers occasionally vomit their entire digestive system in response to stress or disturbance, but they can quickly build a new one, according to WHOI.
According to the University of Alaska Southeast, a sea cucumber’s respiratory system is made up of two respiratory trees on either side of the digestive tract. Through the bases of the two Y-shaped trees at the anus, water enters the body. A thin membrane transports oxygen into the body cavity.
Sea cucumbers can reproduce asexually or sexually. The technique is not particularly intimate, but sexual reproduction is more common. Fertilization happens when the animals’ released sperm and eggs collide in the water. To be successful, this reproductive strategy requires a large number of sea cucumbers in a community. In fact, these extinct animals can be found in enormous herds in many deep-ocean regions, where they graze on the marine waters’ tiny richness.
Around the world, sea cucumbers can be found in almost every marine environment, from shallow waters to deep waters. Benthic organisms, such as sea cucumbers, are those that reside on the ocean floor. However, because their larvae are planktonic, they drift in the ocean currents.
Sea cucumbers can reproduce sexually through broadcast spawning and asexually through budding, just like their echinoderm cousins. In contrast to broadcast spawning, which involves the fusion of egg and sperm cells in the water column to produce eggs that incubate, hatch into larvae, and grow up to be adult sea cucumbers, asexual reproduction produces a genetically identical clone that does not cycle through most of the species’ life stages.
Each reproductive technique has benefits and drawbacks. For instance, few sea cucumber larvae survive to adulthood, and clones do not support the genetic variety required to keep a species adaptable against present and future changes in the environment. A sea cucumber has a five- to ten-year lifespan on average.
Threats & Conservation
Sea cucumbers are susceptible to overfishing due to commercial fishing and farming practices, in addition to their fragility as larvae. Additionally, they are vulnerable to habitat degradation, illegal fishing, water pollution, climate change, and ocean acidification.