{"id":17069,"date":"2015-07-13T00:05:00","date_gmt":"2015-07-13T07:05:00","guid":{"rendered":"http:\/\/live-hakamagwp.pantheonsite.io\/news\/secret-social-lives-jellyfish"},"modified":"2019-03-20T10:56:23","modified_gmt":"2019-03-20T17:56:23","slug":"secret-social-lives-jellyfish","status":"publish","type":"custom_news","link":"https:\/\/hakaimagazine.com\/news\/secret-social-lives-jellyfish\/","title":{"rendered":"The Secret Social Lives of Jellyfish"},"content":{"rendered":"

Jellyfish are not very smart. \u201cThey have very simple sensory organs, and no brain to process any information,\u201d says marine biologist Stein Kaartvedt<\/a>. Which is why it\u2019s so interesting that, off the coast of Norway, scientists have observed what they\u2019re calling \u201capparent social behavior\u201d in the helmet jellyfish<\/a>.<\/p>\n

Though jellyfish are often found in dense, stinging hordes, they\u2019re not typically thought of as social animals. These blooms, or \u201csmacks<\/a>,\u201d actually have more to do with converging water currents than any sort of intentional schooling behavior.<\/p>\n

Yet by carefully tracking helmet jellies\u2019 movements using sonar measurements, Kaartvedt and his colleagues watched as individual jellyfish somehow took note of other jellyfish swimming directly above them, and then abruptly changed their rate of ascent to sync up with their squishy comrades. The research raises many questions about how jellyfish perceive and interact with the world around them. Even without brains, says Kaartvedt, jellyfish \u201ccan do surprising things.\u201d<\/p>\n

During the day, helmet jellies hide in the deep, avoiding the sunlight. But each night, they propel themselves up from the ocean\u2019s depths to hunt krill near the surface. While most helmet jellies perform this climb alone, Kaartvedt\u2019s data showed that around ten percent seem to team up in groups of two to three.<\/p>\n

As the scientists\u2019 sonar data revealed, helmet jellyfish are capable of recognizing potential swim buddies from a distance of two meters. Yet how they do so, says Kaartvedt, is a mystery.<\/p>\n

When helmet jellyfish swim, their movements only disturb the water within a few centimeters. This makes it unlikely that one is simply \u201cfeeling\u201d the swimmers around it. Likewise, because the tagalongs didn\u2019t follow a direct path (like some plankton do when tracking chemical signals left behind by their kin), the senses of \u201ctaste\u201d or \u201csmell\u201d seem equally unlikely causes for the buddy system.<\/p>\n

These jellies lack anything close to what we\u2019d call eyes, but they do have receptors that let them detect, and avoid, sunlight. So maybe \u201csight\u201d has something to do with the behavior?<\/p>\n

\u201cIn deep water, about 90 percent of all animal types produce their own light, and [the helmet jellyfish] is very bioluminescent,\u201d says Kaartvedt.<\/p>\n

In fact, he says, they\u2019ve done experiments where they put a single helmet jellyfish in a bucket in a dark room and then knocked on the container. The animal, thinking it was being attacked, produced so much light that the people in the room were able to see each other in the darkness. (Jellyfish researchers get into some weird stuff.)<\/p>\n

Still, Kaartvedt can\u2019t say for sure whether the jellyfish are using this bioluminescence to follow each other. And as to why the typically solitary animals would want to hang out with each other? That, too, is a mystery.<\/p>\n

Reproduction could explain the social behavior, he says, but there may be an alternative motivation: cooperative hunting. The researchers developed a \u201cprobabilistic model of cooperation\u201d to see if a few jellyfish working together could catch more krill than a \u201clone wolf,\u201d and the math seems to support the idea.<\/p>\n

So does this mean the oceans are teaming with bioluminescent, pack-hunting cnidarians? Hold your helmet jellyfish. As Kaartvedt says, so far, this is mostly speculation.<\/p>\n","protected":false},"excerpt":{"rendered":"

Do helmet jellyfish play follow-the-leader?\u00a0\u00a0<\/p>\n","protected":false},"featured_media":12565,"menu_order":0,"template":"","format":"standard","meta":{"_acf_changed":false,"om_disable_all_campaigns":false,"footnotes":""},"categories":[],"tags":[],"acf":{"hero_video_url":null,"hero_video_caption":"","deck":"Do helmet jellyfish play follow-the-leader?","authors_group":[{"by_group":"by","contributors_group":[15570]}],"word_count_override":"","podbean1":"","podbean2":"","redirect":"","geolocation":null,"related":[16130,16980],"twitterimage":13480,"facebookimage":13480,"twitterdescription":"","edited":"","factchecked":"","code":"","no_old_story_flag":[]},"_links":{"self":[{"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/17069"}],"collection":[{"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/types\/custom_news"}],"version-history":[{"count":1,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/17069\/revisions"}],"predecessor-version":[{"id":19927,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/17069\/revisions\/19927"}],"acf:post":[{"embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/16980"},{"embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/features\/16130"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/media\/12565"}],"wp:attachment":[{"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/media?parent=17069"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/categories?post=17069"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/tags?post=17069"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}