{"id":29289,"date":"2026-07-18T13:55:49","date_gmt":"2026-07-18T17:55:49","guid":{"rendered":"https:\/\/www.ecoportal.net\/en\/?p=29289"},"modified":"2026-07-18T13:56:17","modified_gmt":"2026-07-18T17:56:17","slug":"squid-brains-shrinking-ocean-acid","status":"publish","type":"post","link":"https:\/\/www.ecoportal.net\/en\/squid-brains-shrinking-ocean-acid\/29289\/","title":{"rendered":"Scientists have discovered that squid brains are shrinking as the ocean becomes more acidic, leaving them to lose their eyesight and hunting skills"},"content":{"rendered":"

When Garett Allen pulled up brain scans from squid raised in acidified seawater, his first instinct was to blame the software. The brains looked impossibly small \u2014 roughly half the size he expected<\/strong>. He ran the diagnostics again.<\/p>\n

The images were accurate.<\/p>\n

Allen’s team had grown bigfin reef squid for 90 days in water tuned to match ocean chemistry projected for 2100. Body size stayed normal. Only the brains had changed \u2014 and the losses weren’t spread evenly<\/strong>.<\/p>\n

An experiment built to simulate the future ocean<\/h2>\n

The study grew out of a long-running collaboration between researchers in Canada and Taiwan. Their setup was deliberately simple: raise bigfin reef squid for 90 days in one of two water systems \u2014 one matching today’s ocean chemistry, the other reflecting the more acidic conditions that ocean acidification is projected to bring by 2100<\/strong>.<\/p>\n

The rearing took place at the Marine Research Station of Academia Sinica in Taiwan, under project lead Yung-Che Tseng. Once the squid completed their 90-day lives, the team preserved the animals’ heads and scanned them using a form of MRI that maps soft tissue in fine detail.<\/p>\n

One result stood out immediately as a potential confound: body size. If acidified squid were simply smaller overall, smaller brains would be unremarkable. Body size didn’t differ between the two groups, though. Measured against body length, the acidified squid still came up dramatically short. The brain changes were real \u2014 and selective<\/strong>.<\/p>\n

Where the brain loss hit hardest<\/h2>\n

On average, brain volume in the acidified squid was down by roughly half compared to controls. That alone would be striking. What made the finding more specific \u2014 and more troubling \u2014 was where the losses landed<\/strong>.<\/p>\n

The optic lobes, which convert raw visual input into signals the animal can act on, shrank by approximately 50%. The optic tracts, which carry those processed signals onward, were down by nearly two-thirds. These aren’t peripheral structures. For a predator that tracks and ambushes prey using sharp vision, they’re the core of the whole system.<\/p>\n

The retinas themselves appeared largely intact. The sensors were fine. Damage sat downstream<\/strong>, in the tissue responsible for interpreting what the eyes reported. The squid could still receive light. What it lost was the machinery to make sense of it.<\/p>\n

A predator that can see but cannot process what it sees<\/h2>\n

An earlier companion study from the same research group tested visual function directly, recording electrical signals from the eye itself. Basic function at the retina held up under acidification \u2014 yet the same squid hunted poorly. That gap points to the processing centers, not the sensors, as the source of the problem.<\/p>\n

“We think that the reduced willingness to feed may be linked to a decline in visual acuity,” Allen said. The retina looks intact<\/strong>, while the lobe that interprets its signals quietly wastes away.<\/p>\n

Not every cognitive ability broke down. A separate study on the same species found that acidified squid retained their capacity to learn<\/a>, which suggests acidification doesn’t damage the brain uniformly. It appears to strike certain regions while leaving others relatively untouched \u2014 and the visual processing centers, it turns out, are among the most vulnerable.<\/p>\n

Why might an acidic ocean shrink a brain?<\/h2>\n

The underlying mechanism is still an open question. Allen suspects two possible culprits: a brain starved of energy, or one chemically stressed by the effort of coping with acidified blood. The team hasn’t yet determined which explanation holds, or whether both are operating simultaneously<\/strong>.<\/p>\n

Energy is a plausible suspect. Squid already operate near the edge of their metabolic limits, burning fuel rapidly to sustain constant motion and carrying little reserve when conditions turn harsh. Earlier work from the same team found that squid in acidified water burned oxygen far faster overall \u2014 even as the energy supply to the optic lobes was quietly reduced. That combination points to a system under real strain, making difficult trade-offs with limited options.<\/p>\n

Those trade-offs matter. Cephalopods \u2014 the group that includes squid, octopus, and cuttlefish<\/strong> \u2014 are the most cognitively complex invertebrates alive, carrying roughly as many neurons as a dog. Losing half of that neural hardware isn’t a minor adjustment.<\/p>\n

What a half-brained squid means for the ocean food web<\/h2>\n

Squid aren’t a marginal part of marine ecosystems. One analysis of six decades of catch data found that squid, octopus, and cuttlefish populations have been climbing worldwide<\/a> since the 1950s, representing a growing share of ocean life and of the seafood that people depend on.<\/p>\n

Squid occupy the middle of many food webs \u2014 hunting smaller animals while feeding larger ones. Impaired hunting ability doesn’t stay contained. Fewer successful hunts shifts pressure onto the smaller animals squid eat and onto the larger animals that eat squid, in ways that are genuinely difficult to predict. A growing population of predators that can see but can’t process what they see would reshape those webs from the center outward, with consequences rippling in both directions at once<\/strong>.<\/p>\n

What comes next<\/h2>\n

What made these findings possible was anatomy \u2014 something researchers hadn’t examined before. Squid were already known to hunt less successfully in acidified water, but until Allen’s scans, no one had watched the brain itself change shape.<\/p>\n

Allen and Tseng are now scanning squid at 30 and 60 days of age, aiming to learn how early the structural changes begin and how they deepen as the animals mature. Those results were presented at the 2026 Society for Experimental Biology conference, with more detailed findings to follow<\/strong>.<\/p>\n

The ocean conditions these experiments model are still decades away. That gap isn’t a reason for reassurance \u2014 it’s a window. The question researchers are now racing to answer is how much of a squid’s brain disappears before those conditions even arrive.<\/p>\n","protected":false},"excerpt":{"rendered":"

When Garett Allen pulled up brain scans from squid raised in acidified seawater, his first instinct was to blame the software. The brains looked impossibly small \u2014 roughly half the size he expected. He ran the diagnostics again. The images were accurate. Allen’s team had grown bigfin reef squid for 90 days in water tuned … Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":29423,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"rank_math_focus_keyword":"squid","rank_math_title":"","rank_math_description":"A groundbreaking study reveals that ocean acidification is shrinking squid brains, impairing their eyesight and hunting skills, with serious ecological impacts.","footnotes":""},"categories":[83],"tags":[],"class_list":["post-29289","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-earth"],"_links":{"self":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/29289","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/comments?post=29289"}],"version-history":[{"count":0,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/29289\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media\/29423"}],"wp:attachment":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media?parent=29289"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/categories?post=29289"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/tags?post=29289"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}