Divers Encounter 26-Feet-Long Giant Sea Worms That’s Actually a Colony of Smaller Creatures

Back in 2019, two divers off the coast of New Zealand found a giant floating creature that resembled a worm. Measuring some 26 feet long, it was pink and slightly translucent, like a plastic bag drifting toward them.

In an article from National Geographic, videographer Steve Hathaway was filming with his friend Andrew Buttle. Seeing something unusual off the waters, they put on their scuba film and tried filming that giant translucent sea worm. It was large enough that they were even able to swim around it.

They later learned that what they found was called a pyrosome, and it was not what it first looked like.

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Sea Squirts, Cockroaches of the Sea: A Colony of Small Creatures

Pyrosomes are actually free-floating colonial tunicates, or marine invertebrates, that is cylindrical or even cone-shaped when seen drifting around. They are usually found in warmer waters, though others thrive in the deeper parts of the ocean, with the colony growing up to 60 feet (18 meters) long, according to The Atlantic.

While they look like large, singular beings, pyrosomes are actually made up of hundreds or even thousands of small organisms called zooids. These zooids are singular organisms that compose a larger, colonial animal. Together, they filter their food by allowing water to pass through their bodies, trapping smaller plankton, as well as excrement and waste materials from other creatures. It led to these creatures earning the names such as "cockroaches of the sea" or "sea squirts."

Usually, their feeding habit involves swimming up to the surface of the ocean at night and diving back down into the depths as the sun rises. This behavior was widely believed to be for survival purposes since the colony doesn't have any form of defense against predators - and they are basically a large group of small planktons themselves.

An Illuminating Ecological Agent

While there are a lot of bioluminescent creatures under the water, planktons chief among them, pyrosomes have been noted in this aspect in that their light is brighter than most, and sustains its own light emission. According to research in The Biological Bulletin, this sustained lighting in this colonial animal is caused by individual zooids detecting bioluminescence and emitting it in return, received by the next zooid that exhibits a similar response. In this study, researchers applied induced bioluminescence, finding that repetitive and regular stimulation elicited rhythmic flashing from the pyrosomes, characterized by repeating cycles of low and high light intensities.

Providing further insights on the mysterious colonial animal, a 2018 study was published in the Limnology and Oceanography journal. The new study focused on the Pyrostremma spinosum, a large tropical pyrosome often found in the Eastern Tropical Pacific. Examining its unique ecological role, researchers tracked its grazing and trophic behavior. The study suggests that pyrosomes consume large quantities of phytoplankton below the mix-level areas in the ocean and affects the particles that drop to the depths of the ocean.

Similarly, a separate observation of pyrosomes reported in the Scientific Reports journal, this time in the Cabo Verde ecosystem in Africa, shows that their feeding habits help in the formation of dense forms. This byproduct of their feeding patterns, in turn, affects the food web dynamics in the ecosystem and even helps in the transport and synthesis of organic carbon in the oceans.