The feeding trick looks simple from a distance. Look closer and a strange physics problem comes into view.<\/p>\n That problem sits at the heart of a new set of calculations. The answer touches on how the biggest animals on Earth manage to eat at all.<\/p>\n Giant gulps of krill<\/p>\n When a fin whale lunges, it drops its lower jaw and lets the ocean pour in. The mouth balloons into a huge pouch that runs from the chin back toward the navel.<\/p>\n \u201cWhen fin whales lunge, their lower jaw hinges open and water floods into a pouch stretching from their lower jaw to their belly button,\u201d said Ingrid Ackermann of\u00a0Stanford University<\/a>.<\/p>\n A 66-foot fin whale can take in roughly 2,100 cubic feet of seawater at once.<\/p>\n As the pouch fills, its surface stretches from about 328 square feet to roughly 850 square feet.<\/p>\n That is a mouthful close to the size of a small room. Water rushes in, and then all of it has to come back out through the baleen.<\/p>\n A clogged filter<\/p>\n Racks of baleen hang from the roof of the mouth. These fringed plates work like a strainer that traps prey while letting water slip away. Here is where the trouble starts.<\/p>\n A single gulp can hold up to 317 pounds of krill. When pressed flat against the baleen, a layer would form about 2.5 inches deep.<\/p>\n It would blanket a filter covering only 31 square feet. Normally, a whale clears its mouth in 31 seconds. <\/p>\n Any blockage could stretch that window and cut into feeding time.<\/p>\n The pouch pushes water<\/p>\n Ackermann teamed up with her colleagues David Cade, Jeremy Goldbogen and Mark Denny at Stanford University to work it out.<\/p>\n The team calculated the force made as recoiling blubber and muscle press on the trapped water.<\/p>\n The pouch could push with pressures between roughly 0.6 and 2.6 pounds per square inch.<\/p>\n On paper, that push looked strong enough. It could empty a clean mouth in the target 31 seconds.<\/p>\n Krill from a pet store<\/p>\n Krill happen to be a common food in the pet trade, so Ackermann simply bought a frozen bag from a local shop.<\/p>\n She packed the bottom of a five-foot clear tube with krill. The layers ranged from three-quarters of an inch to about 2.2 inches deep.<\/p>\n Filling the tube with water created pressures close to what a whale can manage. A camera tracked how fast the water trickled through each krill plug.<\/p>\n The team then scaled those speeds up to whale size. What they found was not kind to the whales<\/a>.<\/p>\n Slowing to a dribble<\/p>\n To clear its mouth in 31 seconds, a whale needs water moving at about 2.2 feet per second.<\/p>\n Through even the thinnest krill layer, the flow crawled at roughly 0.13 feet per second instead.<\/p>\n With the thickest plug of krill, the trickle fell to about 0.07 feet per second. That is a dribble, not a purge. <\/p>\n \u201cThe krill might really be a problem,\u201d said Ackermann.<\/p>\n Far too slow to work<\/p>\n At those speeds, emptying a full mouth would take about 16 minutes. That is roughly twice as long as a normal feeding dive.<\/p>\n Even at full muscular effort, the numbers still fell short. The push needed to drive water through packed krill runs close to twice what the pouch can supply.<\/p>\n A fin whale cannot hold its breath and linger that long.<\/p>\n Sieving prey the simple way clearly does not match what these giants do in the wild<\/a>.<\/p>\n The price of a crowd<\/p>\n There is a deeper irony buried in these numbers. The giant lunge only pays off if the whale scoops up a thick crowd of prey at once.<\/p>\n Yet a thick crowd is exactly what clogs the baleen. The very meal that makes the effort worthwhile might also be the thing that jams the strainer.<\/p>\n Scientists have long thought that dense swarms cover the huge cost of each lunge. If clogging slows every meal, that bargain starts to look shakier.<\/p>\n A helpful, clear window<\/p>\n The team looked for a way out. What if the krill did not spread evenly across the baleen?<\/p>\n If part of the filter stays open, water can rush through the gaps. <\/p>\n The math showed that keeping about 15 percent of the baleen clear would let a whale empty its mouth in 31 seconds.<\/p>\n Another option is to keep the krill afloat inside the mouth<\/a> rather than settled on the filter. Either trick would hold the strainer open long enough to work.<\/p>\n The mystery of how fin whales feed<\/p>\n How a real fin whale pulls this off is still unknown. The tongue might sweep the baleen clean as the pouch empties.<\/p>\n Swirling water inside the mouth might also keep the krill moving. The krill themselves swim, though far too slowly to outrun the rush of water.<\/p>\n The finding leaves a gap in a much bigger story. Whales<\/a> grew to record size partly by gulping dense prey, so fast filtering matters more than it might first seem.<\/p>\n For now, the answer stays out of reach. What is clear is that a fin whale must keep its filter from clogging to feed on cloud after cloud of krill.<\/p>\n The study is published in the Journal of Experimental Biology<\/a>. <\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"There is usually safety in numbers. For a swarm of krill, that comfort can vanish in a single…\n","protected":false},"author":2,"featured_media":795834,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[64,63,128],"class_list":["post-795833","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-au","tag-australia","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/795833","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=795833"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/795833\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/795834"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=795833"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=795833"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=795833"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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\n<\/a><\/p>\n