Sea cucumbers are in a group of invertebrates called echinoderms. They are closely related to sea stars and sea urchins. There are more than 1500 species of sea cucumbers that usually live on the ocean floor. A few species also live in shallow waters. The size of sea cucumbers depends on the species and can range from 2.5 centimeters to 30 to 60 centimeters in length. Most of its species are usually 10 cm to 30 cm long. Depending on the species, their color is red, green, blue, black or brown. Sea cucumbers have a soft body, although they have some kind of skeleton under the body surface. Sea cucumbers have a cylindrical, elongated body, they do not have a brain. They have a simple nervous system consisting of a nerve ring and several nerve branches, and their senses are weak. These strange-looking inhabitants of the ocean floor have a digestive system with only one hole at each end of their chubby body. They are active at night, their body shape can change when necessary. Thanks to this feature, they can even pass through very narrow places. Sea cucumbers often live in large colonies. About 1000 sea cucumbers per square meter can be found on New Zealand’s coasts. The lifespan of sea cucumbers depends on their species, with many living 5 to 10 years. Their entire life revolves around absorbing the seafloor and expelling it again.
Starfish Are Related to Sand Dollars and Sea Urchins
Sea cucumbers are closely related to sea urchins, starfish and sand dollars (in the same class as starfish). This means that it is also an echinoderm (spiny-skinned). Most echinoderms have visible spines, but the spines of sea cucumbers are small ossicles embedded in the skin. These small ossicles belong to the identity of some sea cucumber species. are the only clues visible, they are studied under a microscope because they are so small in size. Sea cucumbers, like other echinoderms, have a water-vascular system and tube feet, but unlike others, the water-vascular system of sea cucumbers is filled with body fluid, not sea water. Sea cucumbers have a mouth at one end of their body and an anus at the other. A ring of tentacles (modified tube feet) surrounds the mouth. Tentacles collect food particles. Some sea cucumbers feed by filtering the water, but most get their nutrients from the bottom of the ocean. As the tentacles are pushed to the ocean floor, food scraps stick to the mucus. Although the tube legs are 5 rows, the movement of sea cucumbers is very slow.
Sea Cucumbers Breathe Through Their Anuses
Sea cucumbers breathe through the respiratory tree, a branched structure connected to their anus. The respiratory tree is located inside the body on both sides of the intestine and is attached to the cloaca (externality). Sea cucumbers breathe by drawing in oxygenated water through the anus (they expand their anal sphincters to suck water into their rectums). Water enters the respiratory tree and oxygen passes into the fluids in the body cavity. Sea cucumbers also allow some fish to live in their anus. A few species of parasitic pearlfish actually live inside the anus of sea cucumbers. While the sea cucumber pumps the water in and out for breathing, pearlfish slowly but surely burrow in through the anus.
Sea Cucumbers Play an Important Role in the Food Chain
Sea cucumbers live in a wide variety of habitats, from shallow coastal areas to the deep sea. They can be found in oceans around the world. The sea cucumber’s diet consists of decomposing organic matter and plankton on the seafloor. Sea cucumbers, which clean up dead animal remains, are important creatures in terms of cleaning the ecosystem. Some sea cucumbers gather their food from the surrounding water, while others find food from the bottom of the ocean. Some sea cucumbers are completely submerged in the sediment at the bottom. Some species swallow the sediment at the bottom, removing food particles and then expelling the sediment in long strips. A sea cucumber can filter up to 45-90 kilograms of sediment per year. Sea cucumber secretions help keep nutrients circulating in the ocean ecosystem.
They are the Unsung Heroes of the Sea Grasses
Sea cucumbers are extremely important to ocean ecosystems. As sea cucumbers crawl around the seafloor, eat and defecate, they help distribute nutrients and remove sediment and excess organic matter from water. Research shows that the presence of sea cucumbers leads to more fertile seagrass beds. By dissolving calcium carbonate and returning it to the water, they help provide the raw materials your corals need to grow their exoskeletons. Higher calcium carbonate levels also increase the alkalinity of the water, acting as a buffer against local acidification. They may not be a keystone species, but their role in aquatic ecosystems is very important.
Sea Cucumbers Can Reveal Their Internal Organs
Sea cucumbers are somewhat incapable of self-defense. Sea cucumber species called sandfish spend the day buried in the sand for camouflage. Others follow different paths. If sea cucumbers are disturbed, the Cuvierian tubercles at the base of the respiratory tree, which is the respiratory organ, can be expelled. In addition to expelling these tubercles, when sea cucumbers feel threatened, overcrowded, or in an aquarium with poor water quality, their internal organs, along with the toxic substance (holothurin), can be thrown towards predators or predators. This process, called evisceration, can occur if the sea cucumber is disturbed or threatened. This process can also occur regularly, possibly as a way for the sea cucumber to rid its internal organs of excess waste or chemicals. All missing organs are regenerated over the next few weeks.
There Are Female and Male Sea Cucumbers
In most sea cucumber species, there are males and females, although there is no external difference. Sea cucumbers can reproduce asexually, that is, on their own, but many species reproduce by laying eggs. In sexual reproduction, sperm and eggs are released into the water. Fertilization, the fusion of male and female reproductive cells, takes place in the water and floating larvae that settle on the bottom of the ocean are formed.
Sea Cucumbers Edible
Many creatures eat it, from fish to sea turtles and humans. Sea cucumbers are considered a special flavor in some Asian cultures and are used as part of traditional medicine. Sea cucumbers extracted from water are gutted, packed with salt, boiled, dried, reboiled, dried again and then shipped to markets in Hong Kong and Singapore. There they are sold to consumers at exorbitant prices, which they re-boil and serve as a high-status dish for special occasions. Their populations are declining all over the world due to their irregular gathering.
Sea Cucumbers Must Be Conserved
Despite being collected and sold for sale, and increased exploitation, the sea cucumbers are still numerous and not on endangered species lists, but in January 2016, guidelines were introduced to restrict their collection in Hawaii due to declining populations of sea cucumbers near the coasts on Oahu and Maui. Also in 2019, 3 sea cucumber species were added to a convention on trade in endangered species (CITES) so that they can be better protected.
Being Examined for Use in Medicine
Sea cucumbers have a connective tissue that can magically go from tough to flexible in just a few seconds. This property is being explored for potential applications to the health and repair of human tendons and ligaments. Although they have been studied for use in medicine, the movements of sea cucumbers are almost impossible to monitor. Even if a tracking device is attached to them, they’ll pull it out of their skin. Even trying to find something as simple as growth rates is a challenge because everything depends on their environment. When two individuals of the same species and age are taken into consideration, they can grow at different rates when placed in different places and then sometimes shrink. If a sea cucumber is starving, instead of dying, it eats itself, gradually shrinking.
Writer: Musharref Ozdas