'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.

  • APNewsBreak: Cosby said he got drugs to give women for sex
    APNewsBreak: Cosby said he got drugs to give women for sex

    PHILADELPHIA (AP) — Bill Cosby admitted in 2005 that he secured quaaludes with the intent of giving them to young women he wanted to have sex with and that he gave the sedative to at least one woman and other people, according to documents obtained Monday by The Associated Press. …

  • Longtime Hollywood producer Jerry Weintraub dies at 77
    Longtime Hollywood producer Jerry Weintraub dies at 77

    NEW YORK (AP) — One of the last of the classic Hollywood showmen, Jerry Weintraub built his show business empire on a Rolodex and chutzpah. …

  • 'Can't Buy Me Love' actress Amanda Peterson dies at 43

    GREELEY, Colo. (AP) — Amanda Peterson, best known for her role in the 1987 romantic comedy "Can't Buy Me Love," has died. She was 43. …

  • Michael Buble & Wife Expecting

    Michael Buble will soon be crooning for three. His wife, Luisana Lopilato, is pregnant. …

  • Lady Gaga and Tony Bennett 'cheek-to-cheek' at Montreux jazz fest
    Lady Gaga and Tony Bennett 'cheek-to-cheek' at Montreux jazz fest

    By Stephanie Nebehay MONTREUX, Switzerland (Reuters) - Pop star Lady Gaga and crooner Tony Bennett brought a mix of Cole Porter, Duke Ellington, Frank Sinatra and even Edith Piaf to a sell-out crowd spanning generations at the Montreux Jazz Festival on Monday night. Legendary producer Quincy Jones introduced the odd American couple, praising Gaga as a singer who had "blown his mind." He also recalled working on the musical arrangement for Bennett's 1966 hit "Girl Talk." "This would be …

  • Bill Cosby said in 2005 lawsuit he gave Quaaludes to women for sex
    Bill Cosby said in 2005 lawsuit he gave Quaaludes to women for sex

    Comedian Bill Cosby testified in 2005 that he had obtained Quaaludes with the intent of giving the sedatives to young women in order to have sex with them, according to court documents unsealed on Monday. Cosby, 77, made the admission during testimony in a civil case brought by a former Temple University employee, Andrea Constand, who alleged that Cosby tricked her into taking drugs before he sexually assaulted her. Cosby's lawyers had argued that the documents would cause severe …

  • The Latest: Accuser's lawyers say Cosby words support claims
    The Latest: Accuser's lawyers say Cosby words support claims

    PHILADELPHIA (AP) — Here are the latest developments from the release of court documents indicating Bill Cosby admitted in 2005 to obtaining Quaaludes with the intent of giving them to women with whom he wanted to have sex: …

  • Disney seeks continued tax exemption from Anaheim, California
    Disney seeks continued tax exemption from Anaheim, California

    By Steve Gorman LOS ANGELES (Reuters) - The "happiest place on Earth" will keep a special tax exemption in Anaheim, California, for 30 more years if the City Council approves the Walt Disney Co's plan for a $1 billion-plus expansion of its theme park complex in the city. The five-member council is expected to vote on Tuesday on the company's proposal to go ahead with its Disneyland Resort makeover in exchange for a continued waiver of any future admission tax the city might impose on …

  • 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. …