Do tunas lay eggs with shell?


Darl from Philippines asks: Do tunas lay eggs with shell?

Fernando de la Gándara, from the Spanish Institute of Oceanography center in Murcia (Spain), answered: Bluefin tuna, as all pelagic teleosts, expels ovules during laying, which are later fertilized with sperm from two or three males that pursue the female. Therefore, tunas do not lay eggs but ovules, which transform into eggs once they have been fertilized. Both ovules and eggs are small crystalline spheres, close to 1 mm in diameter, surrounded by a thin transparent membrane. No shell is present.