Meet Gallon of Milk, one of the most beautiful whales on Earth. Named for her bright, milky hue, the incredibly rare albino grey whale was spotted by marine biologists off Mexico's Pacific coast over the weekend, flanked by her much smaller and darker calf. Gallon of Milk has not been seen since 2009

Spotted as part of the seventh annual whale census conducted by the Commission of Natural Protected Areas (Conanp), Gallon of Milk has kept herself pretty well hidden, despite the luminous glow of her skin that cuts through the surface of the ocean in the footage above. 

"This specimen was observed for the first time during the 2008-2009 season as a whale calf with the albino characteristics for which it was named," Conanp explains

"In the recent sighting, this time in the area known as Alambre Island in the Ojo de Liebre Lagoon, Gallon of Milk was accompanied by a calf that was completely grey, which must mean she has become a mother for the first time."

In the wild, albino individuals are rare on land, they're even more rare at sea, as Laura Geggel reports for Live Science. It occurs in people and animals with a genetic predisposition to lack the melanin pigment - they usually have to inherit recessive genes from both of their parents to be born with albinism, or in rare cases, the recessive genes from just one parent can be enough.

While on land, albino animals fare quite poorly in the wild because that bright white colouring is like a beacon to hungry predators, for very large marine mammals like Gallon of Milk, it's not yet clear just how disadvantaged they are by their more obvious colouring.

With her enormous size, Gallon of Milk might not have too many predators to worry about, but research has shown that she's likely dealing with issues such as reduced heat absorption in colder waters, increased sensitivity to sunlight, and impaired visual communication.

"Probably because of their rarity, researchers haven't publicly concluded whether these albino whales share the same threats as their land-bound counterparts," Story Hinckley from the Christian Science Monitor explains. "Today, the main predators of grey whales are orcas."

Gallon of Milk isn't the only albino whale to capture our hearts - Australia's own Migaloo, an albino humpback whale, makes the occasional appearance off the coast of Botany Bay in Sydney.