Marine sharks and rays ‘use’ urea to delay reproduction
Researchers found that high urea concentrations common in cartilaginous fish, particularly oviparous marine species, allow them to mature and begin to reproduce at a larger fraction of their maximal size.
Diving, snacking, laying eggs! What do different hemoglobin levels mean for gentoo penguins?
Gentoo penguins have to food forage before laying eggs. The amount of hemoglobin in their blood may increase diving capacities. Increased diving may mean more tiny penguin chicks.