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Naked mole-rat

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The naked mole-rat (Heterocephalus glaber) is a unique rodent found in East Africa. They live in the dry grasslands of Ethiopia, Kenya, and Somalia.

These animals are famous for their unusual biology and social behavior. They are the first mammal ever discovered to be eusocial. This means they live in complex groups with specific roles. Their social structure is very similar to insects like ants or bees. This system allows them to thrive in harsh underground environments.

A naked mole-rat colony is divided into different castes. One female acts as the queen and is the only female that breeds. She is often larger than the other females in the group. There are also one to three breeding males. The rest of the colony members are workers. These workers do not reproduce, but they help the group survive. Smaller workers focus on gathering food and maintaining the nest. Larger workers act as tunnelers and react quickly to threats.

Model of naked mole-rat soldiers, workers, and queen
Model of naked mole-rat soldiers, workers, and queen

The workers also cooperate to care for the queen's pups.

Living underground requires specialized physical adaptations. Naked mole-rats have very small eyes and poor visual acuity. They use large, protruding teeth to dig through the soil. Their lips are actually sealed behind these teeth. This prevents dirt from filling their mouths while they work. About 25 percent of their musculature is used just to close their jaws. Their skin is pink or yellowish and lacks an insulating layer of hair. Their thin legs allow them to move through tunnels easily. They can even move backward as fast as they move forward.

These rodents are masters of surviving in low-oxygen environments. Their underground tunnels often have very little air. To handle this, they have underdeveloped lungs and specialized hemoglobin. Their hemoglobin has a high affinity for oxygen, which makes oxygen uptake more efficient. They also have a very low metabolic and respiratory rate. Their metabolic rate is about 70 percent that of a mouse. If they go a long time without food, they can reduce this rate by 25 percent. In air with only 5 percent oxygen, they can survive for five hours. They can even survive for 18 minutes in a zero-oxygen atmosphere. During this time, their heart rate drops from 200 to 50 beats per minute.

Naked mole-rats also handle temperature differently than most mammals. Most mammals are thermoregulators that keep a steady internal temperature. Naked mole-rats are thermoconformers. This means their body temperature tracks the temperature of the air around them. They use behavioral thermoregulation to stay comfortable. If they are too cold, they huddle together for warmth. They may also move to shallow parts of the burrow that are warmed by the sun. If they get too hot, they retreat to deeper, cooler parts of the tunnels.

One of their most amazing traits is their resistance to cancer. In 2013, the journal Science named them "Vertebrate of the Year" for this reason. Researchers found they have a special gene called p16. This gene helps with contact inhibition, which stops cells from dividing too much. They also have a sugary substance called HMW-HA. This substance is five times larger than the same substance in humans. This acts as a barrier to uncontrolled cell growth. Furthermore, their ribosomes produce extremely error-free proteins. These features create a double barrier against the development of tumors.

Naked mole-rats are also incredibly long-lived for rodents. They can live for more than 37 years. This is much longer than the African porcupine, which lives about 28 years. Their mortality rate does not increase with age like most mammals. This is partly because they have excellent DNA repair capabilities. Scientists found that they express DNA repair genes at higher levels than mice. They also have high levels of genes related to mitochondria and oxidation reduction. These biological tools help them maintain health and prevent aging-induced damage over many decades.

Naked Mole Rat Eating
Naked Mole Rat Eating
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Heterocephalus glaber June 2019.webm
File:Model of naked mole-rat soldiers, workers, and queen.jpg
Model of naked mole-rat soldiers,...
File:Naked Mole Rat Eating.jpg
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