“Sea pickles,” “sea worms,” “fire bodies”— these are just a few of the wacky nicknames for one of our ocean’s most mysterious creatures: pyrosomes. Pyrosomes (Family Pyrosomatidae) may look like bizarre jellyfish at first glance, but these quirky critters are uniquely beautiful and play an important role in our ocean’s ecosystems and food web.

Name

The name “pyrosome” comes from the Greek words for fire (pyro) and body (soma). As you might guess, pyrosomes are bioluminescent, meaning they emit light. They produce a light—which is typically green or pink—in response to touch and the presence of other objects nearby. This beautiful display can be seen for many meters under the water.  

Structure

Pyrosomes are actually a collection of hundreds (sometimes thousands) of much smaller animals called zooids. While individual zooids can be only a few millimeters long, they are bound together by shared tissue and a notochord—a nerve connection that resembles a spinal cord. This colony of zooids are packed so tightly they form a gelatinous, bag-like structure called a pyrosome. Pyrosomes typically range in size from an inch to two feet in length. However, some pyrosomes, such as the giant pyrosome, have been recorded at lengths of up to 60 feet.

Feeding

Pyrosomes are primarily free-floating filter feeders that consume other plankton. Each zooid within a pyrosome pumps water from one end of the organism’s body through its plankton filtration system, expelling the filtered water on the other side. While pyrosomes spend most of their time drifting, this feeding mechanism allows them to propel themselves in different directions.

Reproduction

Zooids reproduce asexually by cloning. As hermaphrodites, zooids can fertilize their own eggs, producing genetically identical copies of themselves. This cloning ability also enables pyrosomes to regenerate injured parts of their structure or grow new colonies altogether.

Habitat

Pyrosomes are often found in large clusters of colonies called blooms, which are critical parts of our ocean’s ecosystem and food web. Pyrosomes serve as prey for various marine animals, from birds to turtles and fish. When pyrosomes die, they sink to the seafloor and become essential food for bottom dwellers.

Pyrosomes typically prefer tropical and subtropical waters, such as those in the Gulf of Mexico. However, in recent years, blooms of pyrosomes have been found as far north as Oregon, British Columbia and Alaska, and even in the Southern Ocean.

Take Action

Scientists suspect that warming ocean temperatures are driving the poleward range shift of pyrosomes. They fear that a massive die-off of these organisms could create dead zones that deplete the surrounding waters of oxygen. Issues like rising sea temperatures are just one of the many reasons why Ocean Conservancy is committed to addressing climate change.

To help achieve this vision, Ocean Conservancy promotes sustainable ocean-based climate solutions, works with all levels of government to implement these solutions and helps build demand for climate action. We’re bringing the power of the ocean to the global fight against climate change. But we can’t do it without the help of grassroots supporters like you. Take action now to help Ocean Conservancy confront the climate crisis.