Pyrosomes are colonial tunicates made up of thousands of individuals known as zooids. Each zooid is housed in the common gelatinous tunic that makes up the larger cylindrical “body” of the pyrosome. Zooids filter phytoplankton through branchial baskets by creating feeding currents through the tunic. Although each zooid is only a couple of millimeters in size, pyrosomes can reach up to several meters in length. While alive, these organisms spend the majority of their time in the upper water column, but their remains have been found as deep as 4,000 meters (13,120 feet), where they provide food for a variety of deep-sea animals.
Pyrosomes are bioluminescent, producing brilliant blue-green light. Each zooid can detect light and emit light in response, creating waves of bioluminescence up and down the organism’s body. The bioluminescence of one pyrosome can trigger others in surrounding waters, producing beautiful light shows. The name Pyrosoma comes from the Greek term meaning “fire body.”
Galiteuthis phyllura, also known as the cockatoo squid, lives in the North Pacific from 200 to over 1,000 meters (660 to 3,280 feet) deep. This species has a transparent body and photophores, or light organs, under their eyes. We often encounter them hanging horizontally in the water column with their arms raised above their heads.