Which of the following cannot survive outside the water?

Pisces (fish) are obligate aquatic organisms that cannot survive outside water. They extract oxygen from water through gills and rely on the buoyancy of water to support their body structure. Without water, their gills collapse, preventing oxygen absorption, and they quickly suffocate. Amphibians can live on land as adults, reptiles are fully terrestrial, and birds are aerial/terrestrial - all can survive outside water.