crappie: small sunfishes of the genus Pomoxis of central United States rivers
entity: that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
transfer rna: RNA molecules present in the cell (in at least 20 varieties, each variety capable of combining with a specific amino acid) that attach the correct amino acid to the protein chain that is being synthesized at the ribosome of the cell (according to directions coded in the mRNA)