FORT PIERCE, Fla. -

From 22, to five, and now down to four. The number of short-finned pilot whales continues to dwindle as another life was lost today.

It was a sad Labor Day at Florida Atlantic University's Harbor Branch Rehabilitation Facility in Fort Pierce. The staff has worked around the clock, logging long hours, working to keep the final five whales alive.

But shortly after the 10 a.m. feeding, one of the male orphans was not doing well. Overcome by sickness, he died in the tank where the pod is being rehabilitated.

Losing one of the group took a toll on the mini-pod still swimming and the team trying to save them.

"It's the toughest part of what we do in this whole process," said FAU staff veterinarian Juli Goldstein, explaining the unexpected death.

Even the final four are far from healthy.

"They are somewhat stable but they're still in very critical condition. They are sick, they are fighting an infection of some sort, we're not sure exactly what that is yet," Goldstein said.

What they do know is that these whales were sick well before the pod of 22 beached themselves Saturday morning at Avalon State Park Beach in Fort Pierce.

These smart, social animals are well aware of the death toll around them.

Goldstein continues, "We allow that mourning process to happen, our concern is that another stress has been introduced, another animal has passed in front of them."

Their new "human home" is alien to them. That new home is a type of saltwater intensive care unit. It is a five foot deep, 100,000 gallon tank, which is extremely small and quite shallow for deep-water whales used to diving down 3,000 feet below the surface.

This foreign environment is trying on the juvenile whales, between the ages of six months and three years. The female calf is especially curious. So, the staff has to step up and become substitute parents by feeding, hydrating, weighing, rubbing and even sun-screening the orphans.

"They're needing to adjust and we're working to understand their needs," said Steven McCulloch of FAU's Harbor Branch Rehabilitation Center. "They are still dependent on their mother to learn their social and survival skills and we're doing the best we can to play that role."

Survival is top priority.

Quarantined for now, the pilot whales are a protected species normally not seen so up close and personal.

If there is a silver-lining to the horrible mass casualties, it's that biologists now have the chance to learn much more about a species of whale they rarely encounter.

"This is part of the extraordinary opportunity we have to learn about these animals, ones that we seldom see in the wild," said McCulloch.

The future for the pilot whales is in Fort Pierce as they gain strength, learn to take care of themselves and build up their immune systems. They will probably remain in Fort Pierce for at least a week, maybe a few weeks.

Next stop is SeaWorld for a more permanent rehab location, where they could live for months, possibly a year.

But the ultimate goal is to get them back out into the ocean and returned to the wild.