'Bends' study shows how mammals make mega-dives

Scientists in California have shed light on a marine mystery: how diving mammals can hunt for food at great depths without getting the "bends," according to a new study.

Formally known as decompression sickness, the bends occur when nitrogen gas, compressed in the bloodstream at depth, expands during ascent, causing pain and sometimes death.

Researchers led by Birgitte McDonald at the Scripps Institution of Oceanography netted a female adult California sea lion (Zalophus californianus), anaesthetised the animal and fitted it with loggers to record oxygen pressure in its main artery and the time and depths to which it dived.

The 82-kilo (180-pound) sea lion was then released, and the data from its movements -- 48 dives, each lasting around six minutes -- was sent back by radio transmitter.

At a depth of around 225 metres (731 feet), there was a dramatic plunge in the sea lion's oxygen pressure, signalling that it had collapsed its lung to shut off additional air (and thus nitrogen) to its bloodstream.

Lung collapse in diving mammals is a natural action, in which air-processing alveoli -- elastic, balloon-like structures attached to the bronchi -- are depleted to reduce the size of the organ.

The sea lion kept on diving, reaching a depth of some 300 metres (994 feet) before beginning its ascent.

At around 247 metres (802 feet), the oxygen pressure rose again, pointing to a reinflation of the lung, and then fell off slightly before the sea lion breached the surface.

If the sea lion had collapsed its lung, where did it keep the precious reserve of air to help it survive the ascent?

The answer: in the upper airways -- the large bronchioles and trachea whose tissues cannot dissolve air into the bloodstream.

During the ascent phase, the sea lion draws on this pocket of air to feed the alveoli, the study suggests.

At the end of the experiment, the scientists removed the gadgets from the sea lion before releasing it once more into the sea, according to the research, published in Britain's Biology Letters journal.

Impressive as the California sea lion is for diving skills, it is still outstripped by the emperor penguin, which can reach more than 500 metres (1,625 feet), and the elephant seal, which can forage at more than 1,500 metres (5,200 feet).

Loading...

Editor’s note:Yahoo Philippines encourages responsible comments that add dimension to the discussion. No bashing or hate speech, please. You can express your opinion without slamming others or making derogatory remarks.

  • John Nash: A life of great struggle and even greater success
    John Nash: A life of great struggle and even greater success

    TRENTON, N.J. (AP) — Born to an electrical engineer, and later a precocious and dashing young man who attained an Ivy League education, John Nash seemed destined for a life of stunning success. That he achieved, winning a Nobel Prize in 1994, but not without a struggle with mental illness that would make him a household name even more so than his achievements in mathematics. …

  • Some Native Hawaiians disapprove of 'Aloha' movie title

    HONOLULU (AP) — Some Native Hawaiians disapprove of the name of a movie filmed and set in Hawaii, saying that titling it "Aloha" is a disrespectful misappropriation of culture and simplifies a word that's rich with meaning. …

  • David Letterman drives into retirement with Indy 500 tribute
    David Letterman drives into retirement with Indy 500 tribute

    INDIANAPOLIS (AP) — David Letterman has a new No. 1 on his personal Top Ten list of reasons he loves the Indianapolis 500. …

  • Famed Detroit jazz trumpeter Marcus Belgrave dies at 78
    Famed Detroit jazz trumpeter Marcus Belgrave dies at 78

    DETROIT (AP) — Marcus Belgrave, a jazz trumpeter who graced stages and studios with Ray Charles, Aretha Franklin, Dizzy Gillespie, Joe Cocker and Motown artists galore, died Sunday. He was 78. …

  • Audiard's 'Dheepan' wins Palme d'Or in upset Cannes finale
    Audiard's 'Dheepan' wins Palme d'Or in upset Cannes finale

    CANNES, France (AP) — The 68th Cannes Film Festival was brought to a surprising close Sunday with Jacques Audiard's Sri Lankan refugee drama taking the festival's coveted top honor, the Palme d'Or. …

  • Comedian Anne Meara, mother of actor Ben Stiller, dies at 85
    Comedian Anne Meara, mother of actor Ben Stiller, dies at 85

    (Reuters) - New York-born actress and comedian Anne Meara, known for her opposites-attract comedy routine with husband Jerry Stiller, died over the weekend, her family said on Sunday. Meara, the mother of actor Ben Stiller, died on Saturday, her family said in a statement through a representative, but provided no details about the circumstances of her death. "She is survived by her husband and partner in life Jerry Stiller," the statement said. …

  • Redford to college graduates: World needs you; be fearless

    WATERVILLE, Maine (AP) — Two-time Academy Award winner Robert Redford is encouraging college graduates to be fearless in a world of challenges and to become collaborators with others and the environment to overcome life's daunting difficulties. …

  • Actress, comedian Anne Meara, nominated for 4 Emmys, dies
    Actress, comedian Anne Meara, nominated for 4 Emmys, dies

    LOS ANGELES (AP) — Anne Meara, the loopy, lovable comedian who launched a standup career with husband Jerry Stiller in the 1950s and found success as an actress in films, on TV and the stage, has died. …

  • Beyonce's unretouched L'Oreal photos only latest in her long history of Photoshop controvers …

    Beyonce's unretouched L'Oreal photos only latest in her long history of Photoshop controvers …

    Celebrity News - Fri, Feb 20, 2015 1:47 AM PHT
    Beyonce's unretouched L'Oreal photos only latest in her long history of Photoshop controvers …

    Beyonce’s #Flawless image is embroiled in controversy once again. On Wednesday, a web site called The Beyonce World leaked 224 allegedly raw photos of the musician. The images showed Bey in full makeup for the 2013 L’Oreal ad campaign — but with the kinds of “imperfections” we all have — beauty marks, bumps, creases. In the wake of Cindy Crawford’s unretouched photos, the images have been praised by critics of a beauty industry that sets impossibly high standards, standards that Queen Bey …

  • Taylor Swift reveals ‘Style’ video

    Taylor Swift reveals ‘Style’ video

    omg - Sat, Feb 14, 2015 12:14 AM PHT
    Taylor Swift reveals ‘Style’ video

    The 25-year-old released the video for her third cut from platinum selling album 1989. …

  • My mother-in-law’s personal encounter with the pope

    My mother-in-law’s personal encounter with the pope

    Write Away - Wed, Jan 28, 2015 2:29 PM PHT
    My mother-in-law’s personal encounter with the pope

    For my mother-in-law Mrs. Elsa Yrastorza Yuzon, flying and soaring in the skies is part of her normal routine. But it reached new heights when Pope Francis boarded Shepherd One. …