Story highlights A 30-foot sperm whale beached itself near Tampa, Florida

Sperm whales rarely come so close to shore; it's usually a sign of distress

Scientist decided to euthanize the whale because it would not survive on its own

A beached 30-foot sperm whale near Tampa, Florida, attracted hundreds of onlookers Thursday afternoon as biologist decided to euthanize the animal, according to CNN affiliate WTSP

Sperm whales are rarely seen close to shore, and this whale appeared to be emaciated, according to biologists.

Because the large whale wouldn't have been able to survive on its own, veterinarians from the University of Florida decided to euthanize it.

They gave the whale a strong sedative before administering a drug by plunging a 6-foot needle into the whale's chest cavity to stop its heart.

"Although it looks large and scary, it is a very humane thing to do," said Erin Fougeres, a marine mammal biologist with the National Oceanic and Atmospheric Administration. She added the technique has been used many times before on large whales.

The whale carcass was towed away, and scientists plan a necropsy on Friday.