Pegea socia

Taxon-Order: 
Salpida

click on image for more illustrations

Distribution: 
Cosmopolitan, occurs between 60° N and 45° S.
Habitat: 
Lives in upper 200 m, epipelagic.
Size: 
Aggregate generation: to 120 mm; solitary generation: to 120 mm
Diet: 
Filter feeders; phytoplankton and other small particles.
Predators: 
Medusae, siphonophores, ctenophores, heteropods, sea turtles, marine birds and many fish.
Useful Facts or Characters: 

Both the solitary and aggregate generation have a thick tunic without pronounced thickening around the gut.  In the aggregate generation, body muscle bands 1-2 and 3-4 barely touch and are not fused dorsally.  Body muscle bands 1-2 are dorsally fused and 3-4 are touching but not fused in the solitary generation.  

Natural History: 

Pegea socia can often be mistaken for a similar species named P. confoederata.  In the P. confoederata aggregate generation, the body muscle bands 3-4 meet and are fused.  The video included for this species is said to be this closely related species, P. confoederata; however, the aggregate chain formation in P. socia is very similar.

References: 

video source: http://www.youtube.com/watch?v=8ccMPnY0GQg

Bone, Q., (1998)  The Biology of Pelagic Tunicates, Oxford University Press, Oxford.

Madin, L.P., and Harbison, G.R. (1978)  Salps of the genus Pegea Savigny 1816 (Tunicata:  Thaliacea).  Bulletin of Marine Science 28(2): 335-344. 

van Soest, R.W.M., (1974) A revision of the genera Salpa Forskal, 1775, Pegea Savigny, 1816, and Ritteriella Metcalf, 1919 (Tunicata, Thaliacea). Beaufortia 22: 153-191.

Wrobel, D., and Mills, C. (1998)  Pacific Coast Pelagic Invertebrates:  A Guide to the Common Gelatinous Animals. Sea Challengers, Monterey Bay Aquarium, Monterey, CA.

Yount, J.L. (1954)  The taxonomy of the Salpidae (Tunicata) of the Central Pacific Ocean.  Pacific Science 8: 276-330.