From their bizarre name to their blobby worm shape to the fact that its anus is also a mouth, sea cucumbers are some of the most outlandish things in the ocean. There are more than 1,700 species in the world, each one as otherworldly as the next, most shaped like the titular vegetable (a cucumber), albeit covered in leathery skin and with featuring strange branch-like appendages. It is difficult to imagine that such a creature can even exist, much less be prevalent all over the ocean floor. They're even commonly eaten by humans.
Yet a recent study in the Biodiversity Data Journal, reinforces the idea that sea cucumbers are more than aquatic curiosities; they actually serve an important role in protecting the ocean from human activity.
The researchers describe a newly-discovered sea cucumber that has pale pink violet skin and 214 zig-zagging tube feet. Enjoying a life of crawling the ocean floor to gobble up fish waste, algae and various organic matter, the newly-dubbed Synallactes mcdanieli is named after Canadian naturalist Neil McDaniel. Importantly, the new sea cucumber also does its part to protect the sea from the ravages of human activity like global heating and pollution.
"Knowing the mega-diversity of the ocean is a huge task. The world's oceans are under unprecedented pressure from overfishing, habitat destruction and pollution," study co-author Dr. Francisco A. Solís Marín from the Instituto de Ciencias del Mar y Limnología told Salon. "Sea cucumbers are invertebrates that predominantly feed on detritus and other organic matter and excrete inorganic nitrogen and phosphorous, these helps to reduce the acidity in the ocean and subsequently reduces the negative effects of this phenomenon to other animals and plants."
The news cannot come too soon, as the ocean can use all of the help it can get. In addition to being plagued with suspicious amounts of violence and death, the fishing industry is one of the main contributors to oceanic plastic pollution, which produces massive trash islands of plastic trash that eventually filters into human food. Eight million tons of plastic pollution enter the environment every year, while the ocean is clogged with discarded fishing gear and other industrial pollution.
Even if their contribution is to only take a bite out of the larger pollution pie, every nibble a sea cucumber makes a difference — and we would definitely miss them if they were to ever go away.
"It will have a huge impact if they disappear from the ocean," Marin said. "They help to [produce] oxygen the first 19-20 cm of the ocean floor. They help to clean the water to make it more transparent. Already they have been overfished because they are a delicacy in Asia, and because of their pharmaceutical properties."
This can help fight ocean acidification and ocean pollution. As Marin explained, "Their actions reduce organic loads and redistribute surface sediment, and the inorganic nitrogen and phosphorus they excrete enhances the benthic habitat."
Furthermore, a February paper published in the journal Nature ascertained that sea cucumbers are essential to maintaining the health of coral reefs. As the authors point out, coral diseases are causing coral reefs to enter a state of decline all over the world. In particular, the Acroporid corals (which constitute roughly one-quarter of all Pacific coral species) are endangered because of the rise of these diseases, many of them exacerbated by climate change. But there are other risks as well.
"Coral diseases are commonly sediment-associated and could be exacerbated by overharvest of sea cucumber detritivores that clean reef sediments and may suppress microbial pathogens as they feed," the authors write. "Here we show, via field manipulations in both French Polynesia and Palmyra Atoll, that historically overharvested sea cucumbers strongly suppress disease among corals in contact with benthic sediments. Sea cucumber removal increased tissue mortality of Acropora pulchra by ~370% and colony mortality by ~1500%."
In other words, we really can't understate the importance of sea cucumbers in the web of life. If they die off, they tend to take a lot of other things down with it. Yet there is still a lot we don't know about sea cucumbers, which often have new things to teach us. Earlier this month, for example, a Croatian scientist discovered a rare type of sea cucumber — that is, an albino one.
“In scientific literature, there aren’t very many recorded findings of albino sea cucumbers anywhere in the world," Pero Ugarković from the Institute of Oceanography and Fisheries told Morski.hr. "One of the rare sightings was precisely from the northern Adriatic back in 2006, when an albino sea cucumber of the species Ocnus planci was observed."
This highlights the last problem with humanity's destruction of Earth's oceans: Our species knows very little about the world around us, and there are no doubt many new types of sea cucumbers that we could discover if only they are around long enough to be found.
"The fact that we still discovering new species of shallow marine invertebrates in Alaska and Canada, It tells us how important it continues to be to explore our oceans and learn more about our resources," Marin said. "Scientists estimate that 91 percent of ocean species have yet to be classified, and that more than eighty percent of our ocean is unmapped, unobserved, and unexplored."
