Speaking Squid: How Squid Glow to Communicate in Dark Oceans
The deep, open ocean may seem like an inhospitable environment, but many species like human-sized Humboldt squids are well-adapted to the harsh conditions. 1,500 feet below the ocean's surface, these voracious predators could be having complex conversations by glowing and changing patterns on their skin that researchers are just beginning to decipher.
In a study published Monday in the Proceedings of the National Academy of Sciences of United States of America, scientists from Stanford University and the Monterey Bay Aquarium Research Institute (MBARI) captured and analyzed footage of Humboldt squids off the Northern California coast using unmanned, robotic submarines called remotely operated vehicles (ROVs) to better understand this squid's visual communication.
Humboldt squids hunt in groups, and their collective foraging has been described as a "feeding frenzy." The ROV footage and new research, however, suggest that the squids actually communicate with each other as they hunt and socialize. They do so by changing patterns of light and dark pigmentation on their skin, the study shows. The changes can be seen even in pitch-black deep ocean because the squids make their entire bodies glow in the dark, reports MBARI.
Humboldt squids have numerous, small bioluminescent organs called photophores embedded subcutaneously throughout their muscle tissue that make them glow, the study's abstract explains. They use this "backlighting" to "boost the contrast" for skin patterning changes, says a Stanford University news report.
Chromatophores, or pigment cells embedded in the skin, create those pattern changes, reports Scimex. MBARI reports how those are then "backlit like words on an e-reader screen."
"Maybe they need this ability to glow and display these pigmentation patterns to facilitate group behaviors in order to survive out there," suggests study collaborator Ben Burford in the Stanford report. "Many squid live in fairly shallow water and don't have these light-producing organs, so it's possible this is a key evolutionary innovation for being able to inhabit the open ocean."
Burford and senior author Bruce Robison compared where the light organs are in Humboldt squid to where the most detailed skin patterns appear. They found an overlap of where the most densely-packed photophores were and where the most intricate patterns occur, the Stanford report explains. The finding lends weight to their hypothesis about the squids' evolution and use of background glow and changing skin patterns to communicate, the study postures.
Burford analyzed ROV video of 30 Humboldt squids, identifying individuals and observing their interactions. Keeping track of behaviors and skin patterns while squids were swimming alone, in small and large groups and while feeding, Burford realized that Humboldt squids exhibit specific color patterns when interacting with one another in groups, reports MBARI.
The scientists suggest these color changes are a way for the squids to communicate with one another. MBARI explains that a half-light/half-dark pattern that Humboldt squid often display while feeding could be a warning: "Look out — I'm going to grab that lanternfish!"
The squids are able to move through the darkness with exceptional precision, never colliding or competing for prey, the Stanford report notes. "This suggests that their pigmentation changes may be an effective means of communication, analogous to humans using turn signals in traffic," explains MBARI. Scimex reports that the changes could be a "signaling of intent during competitive foraging."
The scientists also found that the squids used patterns in specific sequences, "similar to how humans arrange words in a sentence," describes MBARI. A small sample size prohibited the researchers from understanding the meaning of these sequences, but they believe that certain patterns modify the meaning of other patterns, creating a form of "syntax" or something akin to an alphabet, MBARI continues.
In squid talk, "One sequence of patterns might mean 'Look out! — I'm going to grab that lanternfish,' but a different sequence might mean 'Look out! — If you don't get out of my way, I'm going to eat you!'" reports MBARI.
Though the exact meaning of the signals remains unknown and though it is too early to conclude whether the pattern changes constitute a "human-like" language, the findings suggest that the squid communications could be a complex form of animal communication never-before described in deep-sea animals.
Burford concludes, telling MBARI, "What I like about this paper is that we're investigating really basic questions about life in the deep sea. Even though the deep sea is the Earth's largest habitat, it's also the least known. So we're still making a lot of exciting discoveries in natural history and animal behavior."
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Kevin T. Smiley
When hurricanes and other extreme storms unleash downpours like Tropical Storm Beta has been doing in the South, the floodwater doesn't always stay within the government's flood risk zones.
New research suggests that nearly twice as many properties are at risk from a 100-year flood today than the Federal Emergency Management Agency's flood maps indicate.
Flooding Outside the Zones<p>About <a href="https://furmancenter.org/files/Floodplain_PopulationBrief_12DEC2017.pdf" target="_blank">15 million</a> Americans live in FEMA's current 100-year flood zones. The designation warns them that their properties face a 1% risk of flooding in any given year. They must obtain flood insurance if they want a federally ensured loan – insurance that helps them recover from flooding.</p><p>In Greater Houston, however, <a href="https://doi.org/10.1111/j.1539-6924.2012.01840.x" target="_blank">47% of claims</a> made to FEMA across three decades before Hurricane Harvey were outside of the 100-year flood zones. Harris County, recognizing that FEMA flood maps don't capture the full risk, now <a href="https://www.hcfcd.org/floodinsurance" target="_blank" rel="noopener noreferrer">recommends that every household</a> in Houston and the rest of the county have flood insurance.</p><p>New risk models point to a similar conclusion: Flood risk in these areas outstrips expectations in the current FEMA flood maps.</p><p>One of those models, from the <a href="https://firststreet.org/flood-lab/research/2020-national-flood-risk-assessment-highlights/" target="_blank">First Street Foundation</a>, estimates that the number of properties at risk in a 100-year storm is 1.7 times higher than the FEMA maps suggest. Other <a href="https://doi.org/10.1088/1748-9326/aaac65" target="_blank" rel="noopener noreferrer">researchers</a> find an even higher margin, with 2.6 to 3.1 times more people exposed to serious flooding in a 100-year storm than FEMA estimates.</p>
What FEMA’s Flood Maps Miss<p>Understanding why areas outside the 100-year flood zones are flooding more often than the FEMA maps suggest involves larger social and environmental issues. Three reasons stand out.</p><p>First, some places rely on relatively old FEMA maps that don't account for recent urbanization.</p><p>Urbanization matters because impervious surfaces – think pavement and buildings – are not effective sponges like natural landscapes can be. Moreover, the process for updating floodplain maps is locally variable and can take years to complete. Famously, New York City was updating its maps when Hurricane Sandy hit in 2012 but hadn't finished, meaning flood maps in effect <a href="https://projects.propublica.org/nyc-flood/" target="_blank">were from 1983</a>. FEMA is required to assess whether updates are needed every five years, but the <a href="https://www.fema.gov/cis/nation.html" target="_blank" rel="noopener noreferrer">majority of maps</a> <a href="https://www.oig.dhs.gov/sites/default/files/assets/2017/OIG-17-110-Sep17.pdf" target="_blank" rel="noopener noreferrer">are older</a>.</p><p>Second, binary thinking can lead people to an underaccounting of risk, and that can mean communities fail to take steps that could protect a neighborhood from flooding. The logic goes: if I'm not in the 100-year floodplain, then I'm not at risk. Risk perception <a href="https://doi.org/10.1088/1748-9326/ab195a" target="_blank" rel="noopener noreferrer">research</a> backs this up. FEMA-delineated flood zones are the major factor shaping flood mitigation behaviors.</p><p>Third, the era of climate change scuttles conventional assumptions.</p><p>As the planet warms, extreme storms are becoming <a href="https://nca2018.globalchange.gov/" target="_blank">more common and severe</a>. If greenhouse gas emissions continue to increase at a high rate, computer models suggest that the chances of a severe storm dropping 20 inches of rain on Texas in any given year will increase from about 1% at the end of the last century to 18% at the end of this one, a chance of <a href="https://doi.org/10.1073/pnas.1716222114" target="_blank" rel="noopener noreferrer">once every 5.5 years</a>. So far, <a href="https://www.rstreet.org/wp-content/uploads/2020/02/195.pdf" target="_blank" rel="noopener noreferrer">FEMA hasn't taken into account the impact climate change is having</a> on extreme weather and sea level rise.</p>
Racial Disparities in Flooding Outside the Zones<p>So, who is at risk?</p><p>Years of research and evidence from storms have highlighted social inequalities in areas with a high risk of flooding. But most local governments have less understanding of the social and demographic composition of communities that experience flood impacts outside of flood zones.</p><p>In analyzing the damage from Hurricane Harvey in the Houston area, I found that <a href="https://doi.org/10.1088/1748-9326/aba0fe" target="_blank">Black and Hispanic residents disproportionately experienced flooding</a> in areas beyond FEMA's 100-year flood zones.</p><p>With the majority of flooding from Hurricane Harvey occurring outside of 100-year flood zones, this meant that the overall impact of Harvey was racially unequal too.</p><p>Research into where flooding occurs in Baltimore, Chicago and Phoenix points to some of the potential causes. <a href="https://www.nap.edu/read/25381/chapter/4#16" target="_blank" rel="noopener noreferrer">In Baltimore and Chicago</a>, for example, aging storm and sewer infrastructure, poor construction and insufficient efforts to mitigate flooding are part of the flooding problem in some predominantly Black neighborhoods.</p>
What Can Be Done About It<p>Better accounting for those three reasons could substantively improve risk assessments and help cities prioritize infrastructure improvements and flood mitigation projects in these at-risk neighborhoods.</p><p>For example, First Street Foundation's risk maps account for <a href="https://firststreet.org/flood-lab/research/flood-model-methodology_overview/" target="_blank">climate change</a> and present <a href="https://floodfactor.com/" target="_blank" rel="noopener noreferrer">ratings</a> on a scale from 1 to 10. FEMA, which works with communities to update flood maps, is <a href="https://www.fema.gov/media-library-data/1521054297905-ca85d066dddb84c975b165db653c9049/TMAC_2017_Annual_Report_Final508(v8)_03-12-2018.pdf" target="_blank" rel="noopener noreferrer">exploring rating systems</a>. And the National Academies of Sciences, Engineering and Medicine recently <a href="https://www.nationalacademies.org/news/2019/03/new-report-calls-for-different-approaches-to-predict-and-understand-urban-flooding" target="_blank" rel="noopener noreferrer">called for a new generation of flood maps</a> that takes climate change into account.</p><p>Including recent urbanization in those assessments will matter too, especially in fast-growing cities like Houston, where <a href="https://authors.elsevier.com/a/1boBRyDvMFW6W" target="_blank" rel="noopener noreferrer">386 new square miles</a> of impervious surfaces were created in the last 20 years. That's greater than the land area of New York City. New construction in one area can also <a href="https://scalawagmagazine.org/2018/01/city-in-a-swamp-as-houston-booms-its-flood-problems-are-only-getting-worse/" target="_blank" rel="noopener noreferrer">impact older neighborhoods downhill</a> during a flood, as some Houston communities discovered in Hurricane Harvey.</p><p>Improving risk assessments is needed not just to better prepare communities for major flood events, but also to prevent racial inequalities – in housing and beyond – from <a href="https://www.npr.org/2019/03/05/688786177/how-federal-disaster-money-favors-the-rich" target="_blank" rel="noopener noreferrer">growing</a> after the unequal impacts of disasters.</p>
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