The naked mole-rat has a long list of traits and adaptations that make them extraordinary. One of which is their eusocial behavior. Defined by division of labor and few select reproducing individuals, this structure is most commonly seen in species of ants and bees.
Overseeing each colony of naked mole-rats is a Queen. She is a dominant female mole-rat who does little work. She devotes her time to reproducing while others care for her and her young.
How Does a Naked Mole-Rat Become a Queen?
A naked mole-rat queen obtains her role by exhibiting dominance over other females. She hormonally and behaviorally subdues them into subordinate positions. A new Queen appears when the previous one dies, or the colony becomes physically separated.
A naked mole-rat is not born a Queen. All mole-rats enter life the same. All social interactions determine the ranking of each individual.
The highest-ranking female is the Queen. She becomes a Queen by fighting other dominant females for the top position when a previous Queen passes away, or the colony is separated.
Colony separation can happen by human movements or natural division, such as a tunnel collapse.
Naked Mole-Rat Queen Anatomy and Appearance
The naked mole-rat Queen is larger than the other colony members. She ranges on the higher end of the scale at 70g or 2.5 ounces. She is identifiable by her abnormal spine shape, which has increased vertebrae spacing to facilitate space for carrying offspring.
The general size range of naked mole-rats ranges from 0.5–2.5 ounces (15g–70g). The Queen is significantly larger than the others, averaging on the high end of the scale.
This larger size helps a young mole-rat battle her way to the top position of Queen.
Apart from her size, she is identifiable by noticeable spinal differences. The Queen’s spine extends by increasing the space between each vertebrate to make space in her body cavity for large litters.
Besides these two defining features, the Queen looks much like any other naked mole-rat with pink, wrinkled skin and prominent incisors.
The Queen is the only female in the colony with a hormone cycle. Her social stature allows her to cycle reproductively and copulate. She controls the colony with her hormonal output in three ways:
- She releases hormones within her urine that stifle the hormones of other females, reinforcing her position.
- Her young gain vital development hormones from eating her feces in their first few weeks.
- The low-ranking mole-rat will receive maternal hormones from consuming her feces, which stimulates them to care for the young.
Tasks of the Naked Mole-Rat Queen
The naked mole-rat Queen is the highest-ranking individual in the colony. She does not collect food or dig tunnels like the other mole-rats.
Her behavior is unique to her role, including:
- Controlling the vocalization dialect of the colony
- Asserting dominance
Naked mole-rats have 17 different documented vocalizations in the form of grunts and squeaks chirps. Each colony has its own dialect. This specific ‘accent’ allows the mole-rats to differentiate between colony members and unfamiliar individuals when they are too far away to smell them.
Since the Queen is a consistent figure throughout many generations of colony members, she retains the integrity of the colony’s vocalizations. If a new Queen emerges, she sometimes changes the dialect.
The Queen is the only female naked mole-rat to reproduce, due to her hormonal control. Other workers support her well-being so she can be successful in producing young.
She chooses 1–3 males to mate with by ranking, size, and age. While she prefers unrelated males who have joined the colony as dispersers of another, she will mate with family members.
|Esterus period||less than 24 hours|
|Gestation||70 days (66–74 range)|
|Litter size||3–12 (can be up to 28)|
|Litters per year||In the wild: 1–5In captivity: every 80 days|
|Size of young||2 grams|
|Lactation period||3–5 weeks|
|Weaning period||3–8 weeks|
The status of the Queen is uncertain. She must continue establishing her dominance over other female mole-rats to retain the position. In addition to stifling the others hormonally, she behaviorally suppresses them with aggression.[7
Her aggression includes hostility towards high-ranking females who pose a threat and shoving all individuals. This begins as soon as the pups are born, so they remain subordinate workers.
Life Span of a Naked Mole-Rat Queen
The general lifespan of naked mole-rats is 30+ years. Their maximum longevity is still unknown. Due to her low-risk lifestyle, the Queen mole-rat often has a proportionally longer lifespan than her subordinates.
A Queen naked mole-rat does very little in the colony aside from reproducing. She doesn’t even tend to her young; other worker mole-rats will act as caretakers ensuring they are nearby to suckle.
The Queen is found either resting, eating, or nursing her young. She rarely moves around extended areas of the colony’s tunnels. Because of this, she remains safe from possible threats such as unfamiliar mole-rats and invading predators.
Naked mole-rats can reach ages over 30 in captivity, but mortality rates are higher in the wild due to predators. General worker mole-rats usually live a few years, while the Queen’s average lifespan is around 17 years.
Naked Mole-Rat Queen Pictures
You can distinguish the naked mole-rat Queen from her colony by her stand-out appearance. She is larger, and her spine is extended and distorted for carrying young.
What Happens When a Queen Naked Mole-Rat Dies?
After the death of a naked mole-rat queen, dominant females will fight to move into the high-ranking role. Dominant females can fight to the death to achieve the role of Queen. The largest and strongest mole-rat often is victorious, ensuring genetic strength within the species. Once a new Queen settles into her role, her hormones will settle down the dominant behavior of other contesting females until they return to worker roles.
Why Do Naked Mole-Rats Have a Queen?
Naked mole-rats are a eusocial species. This is unusual for mammals but helps this species survive in their underground habitat. Eusocial division of labor allows for efficient food collection and protection from predators, meaning the Queen can focus on reproducing. This strategy increased the survival of the young and the species’ success.
How Do Naked Mole-Rats Choose Their Queen?
The politics of naked mole-rats are more like tyranny than a democracy. Other mole-rats do not choose who the Queen will be. Instead, she is the most physically dominating female. She asserts herself over the other females to socially and physically suppress their reproductive hormones, so they exist only as workers.