UPSC CDS 1 2020 GK Paper

Birds and mammals – Four-chambered heart, having two auricles and two ventricles.
Reptiles – three-chambered heart (except crocodile which has 4 chambered heart).
Fishes- Two chambered heart, ex Scoliodon.
Dolphin – Mammal has a four-chambered heart. /p>
Salamander – Amphibian has a three-chambered heart.