Which of the following animals has a three-chambered heart?

1. Two atria (left and right)
2. One ventricle

Animals with a Two-Chambered Heart:

• Found in fishes (e.g., Rohu, Sting Ray).
• Consists of one atrium and one ventricle.
• Blood is pumped in a single circulation loop.

Animals with a Three-Chambered Heart:

• Found in amphibians and most reptiles (except crocodiles).
• Consists of two atria and one ventricle.
• Blood mixing occurs, making it less efficient than a four-chambered heart.

Animals with a Four-Chambered Heart:

• Found in birds and mammals (e.g., Sparrow, Humans, Lions, etc.).
• Consists of two atria and two ventricles, ensuring complete separation of oxygenated and deoxygenated blood.
• Provides higher efficiency in oxygen transport, suitable for warm-blooded animals.

Rohu (Fish):

• Belongs to the Pisces class. Has a two-chambered heart (one atrium and one ventricle).
• Single circulation system (blood flows through the heart once per cycle).

Sparrow (Bird):

• Birds have a four-chambered heart (two atria and two ventricles). Complete separation of oxygenated and deoxygenated blood.
  

Sting Ray (Fish):  where blood flows from the heart to the gills for oxygenation and then to the body.