Pyrosomes, or "fire bodies", are free-floating colonies of marine invertebrates that form gelatinous tubes, and earn their name from the faint blue bioluminescence they display as light passes through the colony. Massive, sudden increases in populations, known as blooms, are frequent occurrences and have been known to completely clog up fishing nets and block the water intakes of coastal power plants.
This review presents a global synthesis of available knowledge on pyrosomes, including current understanding of reproduction, habitat, predation and carbon cycling. Pyrosome colonies can grow at rates of up to 75 per cent per day reaching up to 20 meters in size. In bloom, pyrosomes are able to clear up 95 per cent of total phytoplankton stock. They are themselves consumed by fish, turtles, birds and sea lions.
By collecting pyrosome occurrence records from literature and databases including GBIF and OBIS, the authors developed habitat envelopes that pair observations with habitat measurements and satellite records of sea surface temperature and chlorophyll-a production.
The envelopes encompassing data for eight pyrosome species showed distributions that span wide ranges of both temperature and chlorophyll-a levels. While the dominant species, Pyrosoma atlanticum, occurred in temperatures from 5°C to 25°C, less common species of the Pyrostremma and Pyrosomella genera had narrower preferences for temperatures above 20°C.
The authors conclude by posing the hypothesis that P. atlanticum, forms blooms in high-productivity waters below 18°C and is able to maintain its optimal temperature by daily vertical migration in the water column traveling up to 500 m every night and day.