Occasionally blue whales get lost in the Baltic Sea. The remnants of two blue whales have been identified in Finland. One 19-meter skeleton was found on the bottom of the Gulf of Finland during the construction of Nord Stream pipeline. The vertebrae of a second individual were recovered from a field near Pori on the coast of the Bothnian Sea in 1942 and identified in the Copenhagen Zoological Museum by Magnus Degerbl. Radiocarbon dating revealed the former had wandered into the Littorina Sea over 7000 years ago and perished, while the latter bones were shown to be 800--900 years old.
Answer this question, making sure that the answer is supposed by the text: does a blue whale have a back bone?
yes