lower1. 1  to cause to descend; let or put down: to lower a flag. 2  to make lower in height or level: to lower the water in a canal. 3  to reduce in amount, price, degree, force, etc. 4  to make less loud: Please lower your voice.
Biggest Whale-Basilosaurus (60 Tons). Basilosaurus (Nobu Tamura). Unlike the other mammals on this list, Basilosaurus can't lay claim to being the largest-ever of its breed--that honor belongs to the still-extant Blue Whale, which can grow to as much as 200 tons.
The Life of Mammals. The anatomy of the largest mammal ever to have existed. Everyone has heard of the blue whale, yet they are rarely seen and not often filmed. Sir David's delight at the privileged close up view of one of these ocean giants as it breached right beside him is evident. Although difficult to comprehend, at 30 metres in length and 180 metric tons or more in weight, the blue whale is the largest animal ever known to have existed.