How whales open their huge mouths

Blue whale (c) photolibrary.com A blue whale can consume 500,000 calories in one lunging gulp

Related Stories

Researchers have discovered how very large whales co-ordinate their jaw muscles and bones to take gigantic mouthfuls of prey.

For a blue whale, the largest animal that has ever existed, each mouthful can scoop up 100 tonnes of krill-filled water in less than 10 seconds.

Scientists have now found a sensory organ in whales' jaws which they say links bones and muscles to the brain, making the vast lunging gulps possible.

They report their findings in Nature.

A 500,000-Calorie lunge

Baleen (from a museum display) (c) SPL

When a rorqual whale, such as a blue whale, senses that there is sufficient prey suspended in the water, it dives. Then at some point in that dive it opens its mouth, rotates its body and accelerates in order to force krill-laden water into its mouth

A blue whale has separate right and left lower jawbones, allowing it to expand its gape to approximately 3m in width. Pleats of skin and blubber below the mouth, extending to the belly, form a stretchy cavern to accommodate the vast volume of water

Plates of a comb-like structure called baleen (pictured), which hang from a rorqual whale's upper jaw, trap up to 500kg of small marine creatures - that is approximately 500,000 Calories in a single mouthful

Writing in the journal, lead researcher Nicholas Pyenson, from the Smithsonian Institution in Washington DC, explained that the rorqual whales he studied had "one of the most extreme feeding methods in aquatic vertebrates".

This whale-specific mouth organ seems to facilitate that.

Dr Pyenson said the structure looked like a "gelatinous mess", which could be the reason it was previously overlooked and assumed simply to be a fluid-filled joint between the two lower jaw bones.

By dissecting whale carcasses in fine detail, the researchers found that the structure was actually far more complex.

Found at the front tip of the lower jaws, the structure is laden with nerve endings. The team says that these are sensors which pick up signals from the jaw as it starts to open. Nerves from the organ then send signals to the brain, triggering the whales' dramatic and complex feeding lunge.

The study, carried out with colleagues from the University of British Columbia, was possible because the team had access to carcasses landed at a whaling station in Iceland.

 A fin whale after lunging (left) and a close-up of the anatomy of the new sensory organ (c) Carl Buell (arranged by Nicholas D. Pyenson / Smithsonian Institution) The organ, pictured on the right of this image, is at the tip or "chin" of the whales' lower jaws

"We were able to work with tissue samples that were freshly dead," explained Dr Pyenson. "It was a unique opportunity to look at these animals' anatomy in detail.

"And that's what we'd been missing."

Dr Pyenson and his colleagues examined the jaws of fin and minke whales, dissecting them and using high resolution medical imaging to examine the carcasses.

Finding this structure, the researcher said, "answered a lot of outstanding questions".

A rorqual whale's feeding lunge was "one of the largest biomechanical events on Earth", said Dr Pyenson.

"This shows us how they do it so quickly, co-ordinating the inflation of the throat pouch with the opening of the jaws... and closing their mouth to prevent prey escaping - all in under 10 seconds."

Scientists from the University of British Columbia and the Smithsonian Institution point to a ridge of tissue sampled from the throat pouch a fin whale (c) N D Pyenson / Smithsonian Institution Working at a whaling station allowed the team to dissect freshly dead whales

Dr Bill Sellers, a zoologist from the University of Manchester, said that this was an "amazing discovery".

"They've found an organ we didn't know was there, which is remarkable considering people have been chopping up whales for hundreds of years."

Dr Gareth Fraser from the University of Sheffield added that the discovery revealed a unique adaptation that mammals had made to an "aquatic lifestyle".

It showed, he said, "how much we still have much to discover, even from the largest ocean residents".

More on This Story

Related Stories

More from nature

  • Cardinal fish and ostracodFish filmed spitting 'fireworks'

    Film crew captures ostracods' spectacular defensive lightshow that makes predatory fish spit them out.

  • Arapaima'Locally extinct'

    A giant fish which used to dominate the Amazon river is now absent in many areas


  • DragonflyRapid reactions

    Dragonfly's super quick reactions recorded in slow motion by BBC film-makers


  • Wingless adult male of the midge Belgica antarcticaExtreme survivor

    Antarctic midge's small genome may be an adaptation to its extreme environment


  • Myotis midastactus specimen (previously identified as Myotis simus)Golden discovery

    A bat from Bolivia is described as a new species by scientists


  • Dinosaurs 'shrank' to become birds

    Huge meat-eating, land-living dinosaurs evolved into birds by constantly shrinking for over 50 million years, new research shows.

  • Would we starve without bees?

    Honey bees are under threat, and as pollination significantly contributes to the food we eat, what would we do without them?

  • Eggshells may act like 'sunblock'

    Birds' eggs show adaptations in pigment concentration and thickness to allow the right amount of sun for embryos, scientists say.

  • Female shrimps are more aggressive

    Female snapping shrimps are more aggressive than males when defending their territories despite their smaller claw size, a study shows.

BBC iWonder

  • Honey bee close-upInsect intelligence

    Are honey bees as smart as your sat nav?

  • Tyrannosaurus rex skull (c) Mark Williamson / Science Photo LibraryDinosaur dynasty

    One group of dinosaurs survived and their descendants can be seen all around us today


  • Brown rat cluse upRise of the rodent

    Reports of giant, 'super rats' are filling the headlines. But why are we being overrun by rats?


  • Cuckoo portraitHoliday hotspot

    What makes the UK such an attractive destination for visiting wildlife?


There have been 75 solar eclipses and 167 major volcanic eruptions in my lifetime

Nicole Malliotakis on Twitter comments on the events that have happened since she was born by using our personalised Your Life on Earth interactive infographic.

Get Inspired

ACTIVITY FINDER

More Nature Activities >

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.