page_title: Pyrosoma atlanticum
section_title: Description
hierarchical_section_title: Pyrosoma atlanticum / Description
caption_attribution_description: English: Pyrosoma atlanticum, a pelagic tunicate -- a colony of zooids in a gelatinous "tunic". Found this by a tide pool at Point Pinos.
context_page_description: Pyrosoma atlanticum is a pelagic species of marine colonial tunicate in the class Thaliacea found in temperate waters worldwide. The name of the genus comes from the Greek words pyros meaning 'fire' and soma meaning 'body', referring to the bright bioluminescence sometimes emitted. The specific epithet atlanticum refers to the Atlantic Ocean, from where the first specimen of the species was collected for scientific description; it was described in 1804 by François Péron, a French naturalist.
context_section_description: A colony of P. atlanticum is cylindrical and can grow up to 60 cm (2.0 ft) long and 4–6 cm (1.6–2.4 in) wide. The constituent zooids form a rigid tube, which may be pale pink, yellowish, or bluish. One end of the tube is narrower and is closed, while the other is open and has a strong diaphragm. The outer surface or test is gelatinised and dimpled with backward-pointing, blunt processes. The individual zooids are up to 8.5 mm (0.33 in) long and have a broad, rounded branchial sac with gill slits. Along the side of the branchial sac runs the endostyle, which produces mucus filters. Water is moved through the gill slits into the centre of the cylinder by cilia pulsating rhythmically. Plankton and other food particles are caught in mucus filters in the processes as the colony is propelled through the water. P. atlanticum is bioluminescent and can generate a brilliant blue-green light when stimulated.
caption: Pyrosoma atlanticum washed up on the beach in California
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