Aquatic invertebrates have more selenoproteins than terrestrial organisms. Numbers of detected selenoproteins were plotted against the total number of available (redundant) ESTs for organisms that are represented by more than 25,000 ESTs. Vertebrate ESTs were excluded from this analysis due to large size of these organisms. Blue circles correspond to aquatic and brown squares to terrestrial organisms. The difference is statistically significant (P value is less than 2 × 10-6).