Pyrosome - colonial salp

What you see in the photo is not a single organism, but a colony of tunicates of the genus Pyrosoma.

Colonies of pyrosomes may reach a length of 60 cm and forms a distinctive rigid tube that may be colorless, pink, grayish or blue-green. One end is closed and tapered, with the opposing open end having a diaphragm.  The tube has a rough texture due to papillae on the individuals making up the colony. 

Unlike salps that use pulsing of the body wall to pump water, pyrosomes depend on cilia to move water through the body.

Pyrosomes are brightly bioluminescent. In fact, the genus name Pyrosoma is derived from the Greek, pyros (fire) and soma (body), referring to the bright bioluminescence characteristic of this group.   

[Animalia - Chordata - Tunicata - Thaliacea - Pyrosomida - Pyrosomatidae - Pyrosoma

References: [1] - [2]

Photo credit: ©Nick Hobgood | Locality: Atauro Island Dili, East Timor

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