Unlike other vertebrates, amphibians have contractile vessels called lymphatic that pump fluids through the lymphatic system.

Lymphatic hearts

Explanation:

Lymph hearts are usually defined as an organ that pumps lymph and is commonly found in the amphibians, reptiles, and lungfishes. These lymphatic hearts have variation in sizes, ranging from smaller microscopic type in case of lungfish to about 20 liters of capacity in case of many bigger dinosaurs.  

In the case of amphibians such as toads and frogs, these lymph hearts are located in the vein junction and the hearts pump at a much faster rate in comparison to the blood heart. The amount of volume pumped is really astonishing. For example, there are about 10-20 lymph hearts in frogs and salamanders, but caecilians are found to contain more than 100 lymph hearts.