The blue whale is not only the largest animal alive currently, but is likely the largest animal ever to have lived.
Depending on the location, blue whales can grow to be 33 meters (108 feet) and weigh as much as 181 metric tons (200 imperial tons).They can live to be 90 years old and ingest about 3.6 metric tons (4 imperial tons) of krill each day. Blue whale are considered endangered by the IUCN.
More info: http://1.usa.gov/13eRd10
Photo via: Harry Wilson
also if image too small; https://fbcdn-sphotos-f-a.akamaihd.net/hphotos-ak-prn1/1010946_619398494747832_1422589695_n.jpg