Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

Extreme Animals

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Avian red blood cells produce hydrogen sulfide to maintain cell integrity and longevity

Birds have strange red blood cells, at least in comparison to mammals. While they both are responsible for transporting oxygen molecules throughout the body, avian red blood cells have mitochondria and a nucleus. Mammalian red blood cells, on the other hand, are missing a nucleus as well as organelles. By eliminating these structures, mammalian red blood cells are able to carry more oxygen molecules and fold more easily to fit […]

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Cholesterol levels in tissues change during hypoxia in naked mole rats

Naked mole rats are rather famous from a physiological perspective for their amazing ability to live in hypoxic conditions. They do so in part by reducing their metabolic rate. In fact, researchers at the University of Ottawa in Canada showed that reducing environmental oxygen levels to 11% resulted in a 34% decrease in the animal’s metabolic rate. Studies of hypoxia-tolerant goldfish show that the animals respond to hypoxia challenges by […]

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Evolution of pain resistance

Could you imagine eating a pile of chile peppers or spicy hot mustard and not feeling any pain? The ability to sense pain is physiologically quite important as it alerts us to potentially dangerous or poisonous chemicals. Many plants (stinging nettles, pungent bulbs, hot chilies) and animals (stinging ants, scorpions, snakes) produce noxious chemicals to protect themselves from predators. In turn, some predators have evolved resistance to these chemicals. An […]

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The key to the fountain of youth?

I just read an interesting article on the physiology of long-lived species that was published in Physiology. Some animals seem to have discovered the secret to the fountain of youth. Take the long-lived naked mole rat (Heterocephalus glaber) for example. These animals are able to maintain juvenile traits across their lifespan by growing slowly, having low levels of hormones responsible for development and delaying the onset of sexual maturity. Dwarf […]

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First ever recording of heart rate in free swimming blue whales

While we are on the topic of whales, I found additional research published in the Proceedings of the National Academy of Sciences USA on these animals and how their hearts function that I find fascinating. Talk about extreme physiology! Researchers from Stanford University were able to attach surface electrodes to blue whales using suction cups. This allowed them to measure – for the first time – how heart rate changes during […]

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Researchers explore how the largest animals get enough to eat

Ever wonder how baleen whales (Mysticeta) get enough to eat? The mechanism is described for rorqual whales (Balaenopteridae) in a review article published this past October in Physiology. Researchers have found that rorqual whales (ex: blue whales and fin whales), in particular, have an interesting strategy for foraging. The process includes 5 steps that take place in rapid succession (about 20-90 sec total): quick forward lunges toward prey; opening their […]

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Tardigrades are not so tolerant after all

…at least when it comes to dealing with warming temperatures. In contrast to their reputation for being able to withstand almost any extreme environment (radiation, cold, drought, vaccuum of space), researchers at the University of Copenhagen have found that tardigrades may have an Achilles heal. They appear intolerant of sustained increases in temperature.  Study author Dr. Ricardo Neves was quoted in Science Daily, “The specimens used in this study were […]

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