Antarctic Octopus Is a True Blue Blood

Being a blue blood in the Antarctic turns out to be a very good thing, especially if you're an octopus. Continue reading →

An Antarctic octopus gives literal meaning to the phrase "blue blood," as a new study finds the cephalopod has blue pigments in its blood that allow it to survive sub-zero temperatures and possibly higher temps associated with climate change too.

The findings, published in the journal Frontiers in Zoology, help to explain why the Antarctic octopus -- Pareledone charcoti -- is faring well now, while other animals in its habitat are not.

"This is the first study providing clear evidence that the octopods' blue blood pigment, haemocyanin, undergoes functional changes to improve the supply of oxygen to tissue at sub-zero temperatures," said lead author Michael Oellermann, from the Alfred-Wegener-Institute, in a release.

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"This is important," he continued, "because it highlights a very different response compared to Antarctic fish to the cold conditions in the Southern Ocean. The results also imply that due to improved oxygen supply by haemocyanin at higher temperatures, this octopod may be physiologically better equipped than Antarctic fishes to cope with global warming."

The Antarctic Ocean is home to these fish, the octopus, and many other creatures despite the region's history of inhospitably cold temperatures. While it can be hard to deliver oxygen to tissues in the cold due to lower oxygen diffusion and increased blood viscosity, ice-cold waters already contain large amounts of dissolved oxygen.

With that in mind, and hoping to learn more about the sturdy "blue blood" octopus, Oellermann and his team collected and analyzed the haemolymph (a fluid equivalent to blood) from the Antarctic octopus. They also did this for two other octopus species collected from warmer climates: the Southeast Australian Octopus pallidus and the Mediterranean Eledone moschata.

All of these marine animals possess three hearts and contractile veins that pump haemolymph, which is highly enriched with haemocyanin. This oxygen transport protein is analogous to haemoglobin in humans and many other animals. It leads to blue-colored blood, however, instead of red, which has to do with components in the pigment and how the oxygen is processed in the body.

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The Antarctic octopus had the bluest blood of all, with at least 40 percent more haemocyanin in its blood compared to the other species. This is among the highest levels ever reported.

The Antarctic octopus' haemocyanin was also found to shuttle oxygen between gills and tissue far better when temperatures were above freezing. This is where the other octopuses lagged behind. The ability may help the Antarctic species to tolerate warmer temperatures in addition to the cold.

It could also explain the lifestyle of this animal, which tends to hang out in warmer (well, warmer for Antarctica) shallow waters and rock pools.

Photo: The Antarctic octopus Pareledone charcoti. Credit: Armin Rose

A star at the Monterey Bay Aquarium's new exhibit "Tentacles: The Astounding Lives of Octopuses, Squid and Cuttlefishes" is the flapjack octopus. The name was inspired by its flattened appearance. It is among the most anatomically compressed species in the world. The character "Pearl" in the Disney/Pixar film "Finding Nemo" was based on a flapjack octopus.

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Flamboyant cuttlefish are colorful, and deadly. Its muscle tissue is highly toxic, making it one of only a handful of cephalopods known to be toxic. They can change color to help them sneak up on prey or to scare predators.

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"Dwarf squid are the smallest squid species in the world," Monterey Bay Aquarium aquarist Chris Payne told Discovery News. In addition to this petite creature, the new exhibit features a dozen living exhibits showcasing rotating appearances by up to two dozen species -- many never exhibited before.

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On the other side of the size spectrum is the giant Pacific octopus. It is the largest octopus species in the world. Adults can weigh hundreds of pounds and have an arm span of more than 12 feet. The giant Pacific octopus is a master of disguise, like many other cephalopods. It can change both its skin texture and color in order to defend itself.

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A cuttlefish moves by undulating a delicate fringe that runs along its entire body, but for a quick getaway it expels a forceful stream of water through its siphon, according to Monterey Bay Aquarium aquarist Bret Grasse. When threatened, cuttlefish can produce a cloud of ink called sepia. Long ago, this dark-brown ink was used for writing and drawing.

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These are bigfin reef squid eggs, which were collected from the northern Indo Pacific, Monterey Bay Aquarium aquarist Alicia Bitondo told Discovery News. She added, "There are about 300 egg pods in this tank, with about 6 embryos per pod." She and others at the aquarium are breeding the species through multiple generations as one of the featured exhibit animals in the new special exhibition.

Unlike other species of octopus, the day octopus is more active in the daytime than at night. The day octopus originally arrived at the aquarium via a direct flight from Honolulu, Hawaii, since it is native to waters there. It lives in East African waters as well. The large, almost 3-foot-long predators are short-lived. They survive just one year, on average, and breed only once. Cephalopods, in general, don't live for very long, which is why the aquarium is cultivating cephalopods during the exhibition. "These are all short-lived animals," Monterey Bay Aquarium special exhibits coordinator Jennifer Dreyer said. "Many are species that have never been exhibited for very long by any of our colleagues, or raised through their entire lifecycle. This is definitely a first for any aquarium."

Up to 50 nautiluses will occupy a huge exhibit, with a ceiling-to-floor viewing window. These animals like to hide away safely in their protective shells. Many other cephalopods are equally evasive, desiring to blend into their surroundings for protection and to surprise prey. This can make putting them on display challenging. As Bitondo said, "We're trying to display something that doesn’t want to be seen."

A red octopus' normal color is red or reddish brown, but like many other cephalopods it can change quickly -- in a fraction of a second -- to yellow, brown, white, red or a variety of mottled colors. The red octopus is thought to be a clever animal. In 2012, a tiny juvenile red octopus hitchhiked into the Monterey Bay Aquarium on a sponge. It hid in one of the exhibits for a year before being discovered walking across the aquarium's floor in the middle of the night. The discovery helped to explain why so many crabs had gone missing during that period of time. They had gone into the red octopus's tummy. The then out-of-place octopus was eventually released into Monterey Bay, but the species will be represented by others in the new exhibition.

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The wonderpus octopus is native to the Indo Pacific region. Each individual has unique white markings on its head, allowing scientists to track individual specimens. It, along with other cephalopods, will be part of the new "Tentacles" exhibit at the Monterey Bay Aquarium. The exhibit opens April 12 and runs through Labor Day of 2016.