Question

A few fish species lay very big eggs and have big larvae with functioning gills from early on. However, most fish lay small eggs and the small larvae have no gills until later in life. In 2-3 sentences, discuss the need for gills in small vs. large fish larvae.

Answer 1

For the exhange of ions and gases such as potassium, calcium and sodium, large fish larva have gills even in early stages. One other main reason is that large fish arvas mostly have circulating red cells after hatching phase while small fish larvae doesn't. So, for these reasons small fish larvae have no gills until later in life.