Octopuses and other mimic cephalopods can be the literal embodiment of now you see me, now you don’t. Using both quick colors AND change the texture, octopuses can blend into almost any environment by mimicking things like fish on the seabed or plants that sway with the waves. Continued camouflage of cephalopods makes it difficult for researchers to identify, track and monitor these creatures in the wild, which has limited our ability to study them.
That may change for some species, thanks to new research from the University of California, Berkeley, published in PLOS ONE. UC Berkeley researchers study the lesser Pacific striped octopus (also called the zebra octopus, Octopus shells), found that the animals’ striping patterns appeared to be individualized, similar to our fingerprint patterns. Since this tiny cephalopod was previously recommended as a new model organism for future study, having these octopus fingerprints could help solidify O. chierchie placed as the manifesto of cephalopod research.
Growing laboratory octopuses
Studying octopuses in a laboratory is not for the faint of heart. Most species usually live one to three years and produce only one clutch of eggs during that time, making it difficult to trace any sort of genetic lineage. Their intelligence and mischievous behavior make it difficult to keep them in an artificial habitat. Octopuses are predatory creatures, so they require the mental stimulation of hunting, along with special diets to maintain their well-being. Previous studies have shown that caged octopuses cannibalize each other without adequate nutrition.
O. chierchie turned out to be an exception. His small body makes him easier to keep, and unlike most of his relatives, he will produce a clutch of eggs every 30-90 days, making it easier to trace genetic traits. These octopuses can also live up to eight years. And now, researchers may even be able to identify specific individuals within their studies.
Only one other cephalopod species has previously been identified by its stripes: photogenic Wunderpus, also known as wunderpus. As O. chierchie, wunderpus is a small octopus with individualized black and white stripes. The UC Berkeley researchers were curious to see if this individualization translates into O. chierchie.
Initially, we were just trying to figure out how to breed them in captivity, but we noticed that all individuals looked different and we could easily identify them by their striping pattern, even though they escaped from their labeled jars in the larger aquarium. , explained researchers Benjamin Liu, Leo Song, Saumitra Kelkar and Anna Ramji. Dr. Roy Caldwell, our mentor and private investigator [principal investigator] of the laboratory, recommended to investigate whether this could be useful for the study of this species.
As the team explained: Dr. Christine Huffard, one of Caldwell’s former graduate students, conducted a study of the unique body patterns of Photogenic Wunderpus, a species of Indo-Pacific octopus. In that paper, the authors demonstrated that the body patterns of adult octopuses remain constant in aquaria and captured photos that appear to show the same single octopus in the wild many months apart.
As you get a new clutch of O. chierchie, the team found similarities to what Huffard had seen. We noticed that the baby octopus we were raising seemed to keep the same stripe patterns from the age the stripes were first visible, the stripe pattern never moved, it just grew proportionally to the animal, in each baby octopus that we have raised and observed, they added. We thought it was interesting and noteworthy, and possibly useful for the potential study of the life history and ecology of this species in the wild.
UC Berkeley researchers examined 25 of the 156 octopuses they had in the lab and were able to photograph their striping patterns. Although the patterns didn’t appear until the fifth day of the hatchlings’ existence, these stripes would remain with them for life. The dominant stripes are landmarks on the skin, explained Dr. Z Yan Wang, an assistant professor of biology at the University of Washington. They are dynamic in the sense that they can get darker or lighter. But as far as we know, the particular streaks themselves are permanent.
To test their hypothesis, the UC Berkeley researchers who raise the young asked 38 volunteers to look at photos of two O. chierchie octopuses and try to determine if the animals were different. What they found confirmed that the octopuses had their own type of fingerprint, as the volunteers saw distinct differences 84% of the time, with over half of the volunteers seeing differences 90% of the time or more.
Create colors
To change color, octopuses use a complicated network of pigmented cells and proteins. This network includes chromatophores, pigment-containing cells; a type of cell that reflects color called an iridophore; and more passive leukophores that reflect white light. By combining these three cell types, octopuses can rapidly switch from lighter to darker colors, depending on their environmental cues, such as predation or mating. An obvious example: Angry octopuses turn dark, resembling Darth Vader’s helmet, explained Sy Montgomery, the bestselling author of The soul of an octopus. Those who withdraw turn white like the flag of surrender.
This rapid color change makes octopuses incredibly difficult to track in the wild. Previous researchers have tried to tag and recapture wild octopuses, but this has some obvious difficulties. The tags can damage the cephalopod’s soft tissue or the cephalopod may try to tear off the tag. Other researchers have even tried tattooing or branding wild octopuses, but that too is challenging. The tattoo process can be incredibly stressful and damage cephalopod skin. With the new findings from UC Berkeley, researchers may have discovered a less damaging way to track wild animals O. chierchie octopuses, which could provide enormous information on the intelligence and behaviors of cephalopods.
A model organism
Wang and his team at UW studied O. chierchie for several years and were part of the first research team to successfully grow these octopuses in a lab in 2021. Cephalopods have been really, really important to the study of physiology and the study of neurobiology and behavior for a long time, he explained Wang. [A historical example is] examining action potential mechanisms in muscle tissues that came from studies of the squid giant axon.
Thanks to his work, Wang and his colleagues started fighting O. chierchie to be used as a model organism, such as the fruit fly Drosophila, for the study of animal intelligence and behavior. In an article published in Frontiers of Marine Biology, Wang highlighted the many reasons why O. chierchie make an excellent model organism. As she explained: You don’t need, like, the Seattle Aquarium or anything like that [that big] to host them. Hence, they are quite amenable to the typical size of a laboratory. The capacity of the O. chierchie reproducing more times and living longer than other cephalopods will give Wang and his team of UW researchers more insight into the mating process. These things kind of help us get out of the bottleneck of just being able to meet animals to study, he added.
Given the possibility of identifying individual octopuses within a species or group, Wang’s argument is confirmed O. chierchie become the next model organism. Definitely, really useful from a researchers’ perspective, Wang said.
Helping octopus conservation
Identifying individual octopuses can not only help in the laboratory, but also have big implications for monitoring octopuses in the wild. One implication is the ability to apply photoidentification methods to wildlife studies octopus shells, explained the UC Berkeley team. We hope our work opens the door for future non-intrusive, non-harmful and non-extractive studies to learn more about these fascinating animals.
Learning how these creatures interact with their surroundings can help other experts make more informed decisions about how to conserve octopus populations and avoid poaching or illegal farming. Insights gained from future photographic identification studies of wild populations could help inform when and where to harvest new individuals to help maintain the genetic diversity of captive-bred populations while minimizing the impact on wild populations, the researchers added. UC Berkeley.
Knowing about individual octopuses can also help the general public become better engaged in octopus conservation. Animal stories, such as Digit, the silverback gorilla that researcher Dian Fossey studied in the late 1960s, or Lonesome George, the last of Pinta Island’s giant tortoises, show how relatable and inspiring individual animals can be . With more research, marine biologists may be able to tell the stories of individuals O. chierchie octopuses, approaching these cephalopods, one animal at a time.
PLOS One, 2023. DOI: 10.1371/journal.pone.0265292
Kenna Hughes Castleberryis the science communicator at JILA (a joint physics research institute of the National Institute of Standards and Technology and the University of Colorado Boulder) and a freelance science journalist. Her main writing focuses are quantum physics, quantum technology, deep technology, social media, and the diversity of people in these fields, especially women and people from minority racial and ethnic groups. Follow her on LinkedIn or visit his website.
