16149
As in other requiem sharks , the blacknose shark is viviparous ; after the developing embryos exhaust their supply of yolk , the empty yolk sac develops into a placental connection through which the mother provides nourishment .
 yolk
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:
 yolk