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Hippo sweat could serve as suncreen, insect repellent

Hippo secretion could serve as suncreen, insect repellent

Hippo secretion could serve as suncreen, insect repellent
Fresno Bee
August 20, 2005

Hippo in Botswana

The Hippopotamus

The Hippopotamus (Hippopotamus amphibius) is a large, plant-eating African mammal that spends most of the day submerged in the waters of tropical rivers. Hippos can be 1.5 metres (5 ft) tall at the shoulder and weigh 1,500 kg up to 3,200 kg (3300 up to 7040 lb). They are approximately the same size as the White Rhinoceros and are amoung the largest land animals after elephants.

Despite the popular image of the animal being easygoing and peaceful, the hippopotamus is actually one of the most dangerous animals in Africa, and is said to account for more human deaths than any other African mammal. This is not because they are more aggressive than other African mammals but rather because they are highly territorial and their space often conflicts with that of farmers and tourists.

Hippos are sensitive to sunburn. For additional protection from the sun their skin secretes a natural sunscreen substance which is red colored. This secretion is sometimes referred to as “blood sweat,” but it is not actually blood, nor sweat. This secretion starts out colorless, turns red-orange within minutes, eventually becoming brown.

There are two distinct pigments that have been identified in the secretions, red and orange. The two pigments are highly acidic compounds. They are known as red pigment hipposudoric acid and orange one norhipposudoric acid. The red pigment was found to inhibit the growth of disease-causing bacteria, lending credence to the theory that the secretion has an antibiotic effect. The light absorption of both pigments peaks in the ultraviolet range, creating a sunscreen effect. Hippos all over the world secrete the pigments so it doesn’t appear that food is the source of the pigments. Instead, the animals may synthesize the pigments from precursors such as the amino acid tyrosine. (Saikawa, et al., 2004)


According to an article by Mark Grossi in The Fresno Bee hippo sweat could soon be used to prevent sunburn and protect skin from mosquito bites. Professor Christopher Viney at the University of California at Merced is working on deciphering the molecular structure of skin secretions from the hippopotamus. The research could eventually result in the creation of skin-care products based on compounds produced by the African animal. The text of the article appears below.

Scientists studying hippo sweat
Scripps Howard News Service
August 19, 2005

– Some day, you might smear gooey hippo sweat all over your body, and it won’t be for a bizarre ritual or a television reality show.

You’ll be using a sunscreen with the chemically manufactured sweat of a hippopotamus. Not only will it prevent sunburn, but it will ward off bugs and protect you from skin infection.

As creepy as it sounds, slippery hippo sweat could become the toast of the skin-care industry.

But before hippo sunscreen is hip – or even invented – science must unlock the secret of this massive mammal’s secretions: What makes them work?

In that vein, research on hippo sweat marches forward at the University of California at Merced. Professor Christopher Viney soon will publish what could be a key study on the molecular structure of the secretions.

He studied samples of the reddish fluid over the past year after locating the most logical sweat donor: Bulgy, the hippo at Fresno’s Chaffee Zoo.

“Here’s an animal that spends its whole life in a pool not getting sunburned,” Viney says. “We can learn from nature.”

From Bulgy’s viewpoint, lounging at his zoo exhibit, donating the secretion was, well, no sweat. In fact, not much ruffles Bulgy, a mild-mannered, 6,500-pound specimen. He will be 50 in the next few months, making him one of the oldest hippos in captivity.

But a hippo can get pretty testy if someone invades his space and dabs his forehead in search of a sweat sample. It would be unwise to anger an animal weighing as much as three small SUVs, so Viney says he took no chances.

“Hippos are ferocious and territorial,” says Viney, a University of Cambridge-educated engineer who specializes in bioengineering and material science. “The zookeepers at Chaffee hosed down his indoor enclosure and let him stand on the clean floor for a while. Droplets of his secretions fell to the floor.”

It was not difficult to lure mellow Bulgy outside for a dip in his pool while Viney and his assistant, Amber Zielinski, 16, a Merced High School student, collected the droplets with special instruments.

Viney has examined the samples under a microscope. He has taken many photographs of the enlarged images in the microscope so he can see the way the secretion is formed.

“We need to understand the molecular organization in the secretion,” Viney says.

Hippo secretion is not actually sweat; it’s more like a mucus that helps cool the animal.

Zoo general curator Dale Thompson says Bulgy’s sweat does not look like water or human perspiration. “It’s more gelatinous,” he says.

For some reason, flies don’t seem to land on hippo sweat. It might repel bugs – even mosquitoes, scientists say.

The sweat also seems to prevent infection. Hippos open gashes in the skin of other hippos during violent conflicts.

“Then they wallow in mud and other things,” Viney says. “Hippos are not the cleanest animals, yet their injuries don’t get infected. The suspicion is that the secretion is antiseptic.”

Tsunami-orphaned hippo adopted by 100-year old tortoise – 19-August-2005:
A baby hippopotamus that survived the tsunami waves on the Kenyan coast has formed a strong bond with a giant male century-old tortoise, in an animal facility in the port city of Mombassa, officials said.

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