What is "micropogon undulatus"

Sciaenoid \Sci*[ae]"noid\, a. [L. sci[ae]na a kind of fish (fr. Gr. ?) + -oid.] (Zo["o]l.) Of or pertaining to the Sci[ae]nid[ae], a family of carnivorous marine fishes which includes the meagre ( Sciaena umbra or Sciaena aquila), and fish of the drum and croaker families. The croaker is so called because it may make a croaking noise by use of its bladder; the Atlantic croaker ( Micropogonias undulatus, formerly Micropogon undulatus) and the squeteague are a members of the croaker family, and the kingfish is a drum.

Croaker \Croak"er\ (-?r), n.

1. One who croaks, murmurs, grumbles, or complains unreasonably; one who habitually forebodes evil.

2. (Zo["o]l.) (a) A small American fish ( Micropogon undulatus), of the Atlantic coast. (a) An American fresh-water fish ( Aplodinotus grunniens); -- called also drum. (c) The surf fish of California.

   Note: When caught these fishes make a croaking sound; whence the name, which is often corrupted into crocus.