[Note: Having been placed on the "naturalist disabled list", I was a guest whale watcher aboard the Tails of the Sea for this trip.]
On this afternoon's trip we headed ENE from Plymouth, bound for Stellwagen Bank, and ended up on the eastern edge of the southern end of the Bank, as we have on most trips over the last several weeks. In our vicinity out there, there were well over a dozen humpback whales, feeding in groups of two to five, and the occasional minke whale. We were able to identify, among the humpbacks, Cajun and calf, Perseid and calf, Milkweed, Pele, Pumba, Draco, Eruption, Jabiru, Venom, Springboard, Hancock, and Ventisca.
When we started approaching the first group of humpbacks, one whale's dorsal fin stood out from the rest, even at a moderate distance (see the above image) - the whitish dorsal fin of Ventisca could be spotted right away. Ventisca, first seen in Massachusetts in 2001 (her mother's identity is unknown to us), is an unusually pigmented humpback whale - she has sometimes been described as a "partial albino", but correct terminology would instead refer to her as a ~leucistic~ animal. In most ways, Ventisca does follow the typical western North Atlantic pigment pattern, but she does differ from most in the details.
There actually is no such thing as a "partial albino" - albino animals (including albino humans) totally lack the pigment melanin, and have totally white or pinkish skin, along with whitish hair, feathers, or scales, and have translucent irises in their eyes. (In albinos, any pinkish skin coloring is due to the effect of many skin capillaries showing through, sine they are not masked by melanin, and reddish eyes are due to the capillaries in the retina showing through the cornea, unmasked by any pigmentation in the iris.) However, there are also leucistic animals, who do possess melanin, and who may display pigmentation over various parts of their body (and who have normally pigmented irises), but who may lack surface melanin in various areas - such seems to be the case with Ventisca.
"Ventisca" is the Spanish word for "blizzard", and it is an entirely appropriate name for Ventisca the whale. Unlike the normally dark dorsal fins of the vast majority of humpbacks, both sides of her dorsal fin, even at a distance, appear to be mostly whitish in color (although the leading and trailing edges of the dorsal fin are somewhat darker).
A closer look at Ventisca's dorsal fin (above) shows that the whitish coloring is not uniform, but is the result of a filigree of a variably streaked and blotchy frosting, looking very much like wind-driven snow in a blizzard. This would not seem to be the result of scarring (as occasional white areas on the upper torsos of other humpbacks are usually due to), but does appear to be natural in origin (even if such markings are unusual for the vast majority of humpbacks).
As nearly every whale watcher knows, there are variable amounts and locations for white and black areas on the ventral (underside) surface of humpback tail flukes. In that sense, Ventisca is sort of "normal" (see the above image), but a closer look at the details reveals that Ventisca lacks the clear differentiation between the typically large and definite dark and light areas that most humpbacks display, and instead she shows a rather frosted appearance due to myriad minute black and white markings (image below).
The dorsal surface of Ventisca's flukes is also unusually pigmented as well (although this difference is not overly obvious - and I'll bet that many passengers on this afternoon's trip did not notice this). In nearly all humpbacks (with occasional exceptions due to white scars), the upper surface of the flukes is uniformly dark. But this is not so in the case of Ventisca (image below) - the leading edge of the dorsal surface is whitish, and most of the trailing upper surface is etched by a pattern of small black and white lines and spots. If one were to divide, from front to back, the dorsal surface of her flukes into fourths, it would appear that only the second fourth is dark - the leading one fourth and the trailing two fourths are quite light in comparison.
Why this may often be overlooked is because glare off of the water running off her flukes when lifted in the air may mask this effect. However, an image of Ventisca's flukes taken on an earlier whale watch (below) shows the exact same pattern for her discrete black and white markings.
The mottled pigmentation extends onto Ventisca's ventral surface, too. An examination of Ventisca's caudal peduncle (tailstock) (see the two images from this afternoon below) shows the same unusual pattern of small black and white markings found elsewhere on Ventisca's body.
Both albinism (especially) and leucism in whales are very uncommon. If Herman Melville's 1851 fictional white sperm whale, Moby Dick, did have any basis in reality, it could have come from an actual leucistic or albino sperm whale - in the early 1800's there was indeed a very large and notoriously aggressive white sperm whale in the southeastern Pacific, nicknamed "Mocha Dick" by whalers who unsuccessfully hunted it for many years starting in 1810, before finally killing it in 1838. (The name "Mocha" referred to the island of Mocha, west of the Chilean coast, and not to the whale's color.)
In more recent years there have been occasional albino and leucistic cetaceans both observed and photographed. A pinkish bottlenose dolphin (likely an albino due to its reddish eyes) has been documented swimming along the Louisiana coast since 2007, as has a light gray leucistic orca (killer whale) among the Aleutian Islands since 2008. A mostly white leucistic right whale calf was born in 2008 off western Australia. But the most famous modern white whale has to be the male humpback named Migaloo (Australian Aborigine for "white fella"), who has been witnessed migrating along the eastern Australian coast every year since 1991. (Migaloo does appear to be entirely white, but it is still uncertain if he is a true albino or is "merely" very dramatically leucistic.)
Certainly, "our" Ventisca does not possess the extreme pigmentation (or lack thereof) of the above whales and dolphin, but she does appear to be the most visibly leucistic whale in the Massachusetts humpback population, and she is a beautiful animal to see (but, then again, aren't they all?).
All of the original image files for this day are available at http://www.flukeshots.net/2010/100819/
Categories: Whale Watching