Despite its diminutive stature, this salp is among the kings of all the thaliaceans.  It's probably the most abundant salp off the coast of central and southern California, with dense aggregations covering several thousand square miles reported on occasion.  Thalia is relatively inconspicuous and is the smallest species on the West Coast.  Solitaries have a thick test, length up to 12 mm.  A pair of distinctive projections mark the posterior, and the body has 5 muscle bands.  Aggregate individuals also have thick tests and 5 muscle bands, but only reach about 6 mm length.  Variation among aggregates is great, with some having ridges and grooves and others being smooth and flabby.  Individuals within an aggregate are only loosely held to the chain and are easily separated.  Compared to other species like the various Salpa, aggregates of Thalia are poor swimmers and spend most of the time drifting motionless.  Under the appropriate conditions, individuals of this species can exhibit astounding growth rates, with 10 to 20% increases in body length per hour possible.  With generation times of several days to a couple of weeks, Thalia populations can quickly overwhelm an area.   It is widespread and commonly found in all tropical and temperate oceans.   Despite its abundance, you probably won't see this species too frequently in nearshore waters. 

All photographs © David Wrobel and may not be used or copied without permission!

[ Cyclosalpa affinis ] [ Cyclosalpa bakeri ] [ Dolioletta ] [ Helicosalpa ] [ Iasis ] [ Oikopleura ] [ Pegea ] [ Pyrosoma ] [ Salpa ] [ Thalia ] [ Thetys ] [ Weelia ]