Welcome to DU!
The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards.
Join the community:
Create a free account
Support DU (and get rid of ads!):
Become a Star Member
Latest Breaking News
General Discussion
The DU Lounge
All Forums
Issue Forums
Culture Forums
Alliance Forums
Region Forums
Support Forums
Help & Search
Blue, mysterious and arriving by the millions: the alien-like creatures blanketing US beaches
https://www.theguardian.com/environment/2024/apr/05/blue-tide-west-coast-beachesBlue, mysterious and arriving by the millions: the alien-like creatures blanketing US beaches
Masses of ephemeral organisms known as ‘by-the-wind sailors’ wash up in a ‘blue tide’ on the west coast most years but warmer winter seas could be increasingly their numbers
Katharine Gammon
Fri 5 Apr 2024 07.00 EDT
From Oregon to California, blankets of alien-like blue creatures are washing up on rocky beaches. They are Velella velella, tiny colonies of organisms with a sombrero-esque fin sticking out the top and tentacles dangling down.
Millions have been spotted along the US west coast this spring, much to the surprise and delight of beachgoers who have gleefully posted footage on social media. Some call it a “blue tide” and it happens most springs – but not always to the same degree of abundance.
Though they look like one organism, velella – also known as by-the-wind sailors – are actually colonies of creatures from a class called hydrozoa that use the wind to speed along. They spend most of their lives out in the open ocean, searching the water column below them with tentacles that sting fish larvae or zooplankton, but are harmless to humans. One part of the colony is responsible for eating, another for reproduction. Coral is another colonial organism – but it’s uncommon to encounter such colonies on land, says Anya Stajner, a doctoral student at the Scripps Institution of Oceanography.
There are a few theories about how the animals got their brilliant blue color. Living at the interface of the air and ocean doesn’t offer them many places to hide from predators such as the huge mola mola ocean sunfish, which sucks up velella like candy. Their color might help them disguise themselves by blending in with waves, Stajner says. Another theory is that the color protects them from harsh UV rays – a sort of built-in sunscreen.
…more…
(Maybe someone can post a photo?)
9 replies
= new reply since forum marked as read
= new reply since forum marked as read
Turns out to be something I had already encountered in another context -- the pigment is complexed with proteins which cause (somehow!) the absorbance spectrum to shift. Wikipedia doesn't have much of an article on carotenoproteins, but fortunately one can find other citations:
Carotenoproteins and Carotenolipoproteins
In combination with proteins and lipids, carotenoids also give rise to the wide range of blue, green, purple, and brownish colors of marine life. Complexes of carotenoids and proteins, known as carotenoproteins and carotenolipoproteins, dominate in the exoskeleton of crustaceans, coelenterata, and many other marine species. Although astaxanthin itself appears as a red pigment, when it is complexed with various proteins the light absorbance shifts, which results in green, yellow, blue, and brown colors. This is demonstrated by the appearance of the red color when crustaceans are cooked, which is the result of the denaturation of the proteins and release of the astaxanthin chromophore. The American lobster, Homarus americanus, displays an abundance of green colors but also with shades of black, red and blue, which is almost entirely astaxanthin complexed with protein and chitin. Astaxanthin at over 90% purity has been identified from the blue goose-barnacle within the inner and outer body tissues as well as the ripe eggs. The green astaxanthin protein of lobsters, ovoverdin, persists unchanged until shortly before the eggs hatch, whereby the protein moiety is then released, liberating astaxanthin.
https://www.brineshrimpdirect.com/about-us/articles/natural-astaxanthin/
This may very well be the first citation of brineshrimpdirect.com on DU.
So, that "other context": I knew that the reason lobster shells turn bright red, and shrimp turn pink, when cooked is due to the breakdown of a protein-pigment complex, of a type similar to that in Velella. Apparently, it's even the same pigment, astaxanthin ("xanthin" comes from the Greek word for 'yellow', btw). Since Velella isn't a crustacean I didn't make the connection, but apparently the pigments originate in algae which are eaten by all manner of marine animals, who incorporate the pigments into their own coloration. In fact, shrimp eat algae and use the pigment to color their exoskeletons red ( which is good as black in very deep water, protecting them from predation), but are consumed by salmon in turn, turning their flesh the iconic pink color we all know as "salmon pink".
So, if you were to cook, V. velella, it should turn red or pink!
