All octopi have a remarkable propensity for camouflage, using pigmented organs in their skin called chromatophores to blend in. The same mechanisms allow the octopus to relay messages. Now, researchers have shown that at least one octopus species can manipulate its appearance without use of its central nervous system.
The chromatophores in the species' skin seem to have coopted the basic seeing ability from the octopus's eyes and brain.
"Octopus skin doesn't sense light in the same amount of detail as the animal does when it uses its eyes and brain," Desmond Ramirez, a doctoral student in ecology and marine biology at the University of California, Santa Barbara, explained in a press release. "But it can sense an increase or change in light. Its skin is not detecting contrast and edge but rather brightness."
Ramirez is the lead author of a new study on the two-spot octopus's unique seeing abilities.
Researchers found that the cells of the species' chromatophores swelled and shrank in response to different lights, and that the octopus' skin was most sensitive to light on the blue end of the spectrum. Previous research has identified other marine mollusks with seeing skin, but researchers aren't sure how octopi fit into this peculiar genetic lineage.
"Do they all come from the same ancestral source or did they evolve multiple times?" asked Todd Oakley, a marine biology professor and study co-author. "What kind of behaviors do the different groups share and what kind of behaviors does the skin sensing light underlie?"
Oakley, Ramirez and their colleagues will need to conduct further studies to answer those questions.
The galaxy, named WISE J224607.57-052635.0, belongs to a newly defined class of galaxies known as extremely luminous infrared galaxies, or ELIRGs. WISE was also responsible for helping astronomers find new types of extra-bright star clusters.
Researchers believe an especially hungry supermassive black hole at the center of the galaxy is likely responsible for the galaxy's impressive luminosity. As the black hole swallows the surrounding gas, it emits visible, ultraviolet, and X-ray light. Dust clouds absorb that light, and as they do, they heat up and give off infrared light.
Finding a black hole at the center of a galaxy isn't rare, but finding one this big in a galaxy so far away is unusual and unexpected. Because the galaxy is 12.5 billion light-years away, it offers scientists a glimpse into the universe's past. That means the galaxy's black hole grew very big, very fast, at a relatively young age.
"The massive black holes in ELIRGs could be gorging themselves on more matter for a longer period of time," researcher Andrew Blain, a professor at the University of Leicester's Department of Physics and Astronomy. "It's like winning a hot-dog-eating contest lasting hundreds of millions of years."
ELIRGs are only one of a several new types of galaxies identified by WISE. The telescope's ultra-sensitive infrared instrumentation offer astronomers one of the most detailed and comprehensive views of the universe, revealing stranger (and bright) new specimens never seen before.
"We found in a related study with WISE that as many as half of the most luminous galaxies only show up well in infrared light," said Chao-Wei Tsai, a scientist at NASA's Jet Propulsion Laboratory and lead author of a new study on the super-bright galaxy.
Tsai's paper is published in the Astrophysical Journal.