The milk of blue whales is so rich that it has the consistency of runny cheese – and it has to be to keep their young well fed. The behemoth babies have to put on some 37,500 pounds during the suckling period to make their growth goals! It's thought that calves slurp down 50 to 150 gallons of milk each day to achieve this feat, but catching one in the act of nursing is exceptionally rare.
This amazing drone footage was captured by captain Frank Brennan of Dana Wharf Sportfishing and Whale Watching, during a charter trip along the California coast. Despite operating in the area for 20 years, neither Brennan nor his colleagues had ever seen something like it. 

"We view hundreds of blue whales in the summer," the team wrote on Facebook. "We often have so much footage that we don't always realise what we were able to capture! We've had this since summer and we just dug it up!" To the best of their knowledge, the clip marks just the second time in history that blue whale nursing has been captured on aerial video. 

It's estimated that the mother was 80 feet (24.3m) long. Based on size comparisons, that would have made her calf between four and six months old at the time the video was shot. Blue whales typically suckle for five to seven months, so this one was well on its way to independence. 
Images: Frank Brennan/Dana Wharf Whale Watch
That fatty milk we mentioned? It's 38 percent fat (for comparison, human milk is just four percent), and flows from nipples that are tucked behind folds of skin on the belly, located between the pectoral flippers and the animals' tail flukes. Unlike many mammals, blue whales lack flexible lips, so scientists are not entirely sure how they manage to extract milk from the nipple. Just imagine trying to drink from a straw if you couldn't purse your lips. 

The favoured hypothesis is that the mother whale flexes muscles beneath the mammary glands to quite literally shoot creamy liquid towards the calf's mouth. But since the leviathans' offshore lifestyle and deep dives make filming them underwater quite tricky, it's hard to say with certainty. 

"We don't get to see many blue whales and their calves in the first place," marine biologist Alisa Schulman-Janiger told the OC Register after watching the clip. "To see a blue whale and a calf nursing, everything has to come together perfectly.”

Several videos of suspected blue whale nursing behaviour do exist (like here, for example), but the only other confirmed sighting was filmed by Oregon State University marine ecologist Leigh Torres earlier this year:
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Top header image: Frank Brennan/Dana Wharf Whale Watch