The Collaborative International Dictionary of English v.0.48:

Salpa \Sal"pa\ (s[a^]l"p[.a]), n.; pl. L. Salpae
   (s[a^]l"p[=e]), E. Salpas (s[a^]l"p[.a]z). [NL.: cf. L.
   salpa a kind of stockfish.] (Zool.)
   A genus of transparent, tubular, free-swimming oceanic
   tunicates found abundantly in all the warmer latitudes. See
   Illustration in Appendix.
   [1913 Webster]

   Note: Each species exists in two distinct forms, one of which
         lives solitary, and produces, by budding from an
         internal organ, a series of the other kind. These are
         united together, side by side, so as to form a chain,
         or cluster, often of large size. Each of the
         individuals composing the chain carries a single egg,
         which develops into the solitary kind.
         [1913 Webster] Salpian