76194
The pigment also improves visual contrast and sharpens distance vision , especially in hazy conditions , and helps terns to locate shoals of fish , although it is uncertain whether they are sighting the phytoplankton on which the fish feed , or other feeding birds .
 phytoplankton
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 phytoplankton