Star-nosed mole facts for kids
Quick facts for kids Star-nosed mole |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Condylura
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| Species: |
cristata
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| Star-nosed mole range | |
| Synonyms | |
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Sorex cristatus Linnaeus, 1758 |
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The star-nosed mole (Condylura cristata) is a small mole that lives in wet, low areas in northern North America. It is special because it has a unique nose with over 25,000 tiny touch sensors. These sensors are called Eimer's organs. This mole, which is about the size of a hamster, uses its nose to feel its way around. It can even detect ground vibrations with its amazing nose.
The star-like nose is super sensitive. It is about 1 centimeter wide and has 22 fleshy "fingers" covered with these tiny touch sensors. Other mole species also have Eimer's organs, but not as many or as specialized as the star-nosed mole. Since the star-nosed mole cannot see well, its nose helps it find food. It can identify and eat food incredibly fast, sometimes in less than a quarter of a second! Its brain decides if food is edible in about 8 milliseconds. This speed is almost as fast as nerve signals can travel.
These moles can also smell underwater. They do this by blowing tiny air bubbles onto objects or scent trails. Then, they breathe the bubbles back in to carry the smells to their nose.
Contents
Life and Habitat of the Star-Nosed Mole
The star-nosed mole lives in wet places like marshes and swamps. It eats small creatures such as water insects, worms, and snails. It also eats small amphibians and tiny fish. Sometimes, star-nosed moles are found in drier fields away from water. They have even been seen in mountains as high as 1,676 meters. However, they really prefer wet, muddy areas.
This mole is a great swimmer. It can look for food along the bottom of streams and ponds. Like other moles, it digs shallow tunnels near the surface to find food. Often, these tunnels open up underwater. The star-nosed mole is active day and night. It stays active in winter too, digging through snow and swimming in icy streams. It can keep its body warm in cold water better than other moles. This helps it live in chilly, wet places. Scientists think these moles might live in groups, but not much is known about their social life.
Reproduction and Life Cycle
Star-nosed moles mate in late winter or early spring. The female usually has one litter of four or five babies in late spring or early summer. If the first litter doesn't survive, she might have a second one. When they are born, the babies are about 5 centimeters long. They are hairless and weigh about 1.5 grams. Their eyes, ears, and star-shaped nose are closed. They open and become useful about 14 days after birth. The young moles become independent after about 30 days. They are fully grown after 10 months.
Many animals hunt star-nosed moles. These include red-tailed hawks, great horned owls, barn owls, and screech owls. Foxes, weasels, minks, and different types of skunks also hunt them. Large fish like the northern pike and even domestic cats can be predators.
How the Star-Nosed Mole's Nose Works
A scientist named Kenneth Catania has studied star-nosed moles for 20 years. He says these moles are amazing for learning how brains process information. He calls them a "gold mine for discoveries."
He compared the mole's nose to human vision. When the mole touches something that might be food, it quickly moves its nose. It uses the two smallest "fingers" (called ray 11) to touch the object many times. This is like how our eyes make quick movements to focus on something. The mole's brain pays a lot of attention to these two small rays. This is similar to how our brain focuses on the center of our eye for sharp vision. This shows that evolution often finds similar ways to build very sensitive sensory systems. It uses a large, less detailed area for scanning and a small, super-detailed area for focusing.
The star-shaped nose is truly unique. Since star-nosed moles live in darkness, they rely on their special nose to find and identify food. They don't use their eyes much. This organ is known for being very sensitive and fast. It can decide if something is edible in just 8 milliseconds. This is one of the fastest reactions in the animal kingdom! Because of this, the star-nosed mole is in the Guinness World Records as the world’s fastest forager.
Anatomy of the Star-Nose
The star-nose is a very special sensory organ. It has 22 fleshy, finger-like parts, called tendrils. These tendrils surround the mole's nostrils. They are always moving as the mole explores its surroundings. The star itself is about a centimeter wide. This is slightly smaller than a human fingertip. However, it is much bigger than the noses of other moles.
The star has a high-resolution central area (the 11th pair of rays). It also has less sensitive outer areas. The outer rays (1-10 on each side) scan the environment. They then direct the 11th ray to interesting objects, just like our eyes focus on things.
The star's tendrils do not have muscles or bones. They are not used to grab things or catch prey. Instead, they are controlled by tendons connected to the skull. This allows them to perform their mechanical sensing role. The star's skin is covered with 25,000 tiny raised domes. These domes, called Eimer’s organs, are the only type of sensor on the star. This proves the star's main job is mechanical sensing.
Eimer’s organs are found in almost all mole species. But no other mole has as many as the star-nosed mole. This huge number of sensors makes the star super sensitive. It is about 6 times more sensitive than a human hand, which has about 17,000 sensors.
Each Eimer’s organ has many nerve fibers. This means the star is packed with nerves. All 25,000 Eimer’s organs have a similar basic structure. However, the central 11th pair of rays, which is smaller, has fewer organs. But it has more nerves per organ. This makes it more sensitive for detailed touch.
The star sends touch information to the mole's brain very quickly. The brain also processes this information at an amazing speed. It takes only 25 milliseconds for the mole to decide if something is edible. This includes 12 milliseconds for the brain to respond to touch. Then, 5 milliseconds for commands to go back to the nose. In humans, this whole process takes 600 milliseconds!
More than half of the mole's brain is used to process information from its nose. This is even though the nose is only about 10% of the mole's size. This shows how important the star-like nose is to the mole's life. It acts like the mole's eyes, creating a touch map of its surroundings.
Sensitivity to Touch
Scientists have studied how the star-nose senses touch. They found that different types of Eimer's organs react in different ways. Some organs respond slowly to pressure. Others respond quickly to pressure and vibrations. Some are good at detecting texture. Others are best at feeling vibrations at a specific frequency.
Direction and Speed Sensitivity
The sensors in the star-nose can also tell the direction of a touch. A sensor might react strongly if pressed in one direction. But it might not react at all if pressed in another. The moles' nose moves at about 46 millimeters per second when it's looking for food. The sensors are designed to respond at this speed.
How Touch Signals Become Electrical Signals
When the star-nose touches something, the Eimer's organs change the mechanical touch into an electrical signal.
- First, the touch causes a change in the sensor.
- If the touch is strong enough, it creates an electrical signal.
- This electrical signal travels along nerves.
- Finally, the signal reaches the brain, where the information is processed.
Even though we know these steps, scientists are still learning exactly how this amazing process works.
Behavior of the Star-Nosed Mole
Even with poor eyesight, star-nosed moles have a complex way to find food. When exploring, the mole's star-like nose quickly touches objects or the ground. When looking for food, moles touch the ground in random patterns. Each touch lasts about 20-30 milliseconds.
If the outer parts of the star touch something that might be food, the mole quickly moves its nose. It uses the two central "fingers" (the 11th pair) to explore the object in more detail. This foraging is incredibly fast. The mole can touch 10 to 15 different spots on the ground every second. It can find and eat 8 separate food items in less than 2 seconds. Then it starts looking for more food in as little as 120 milliseconds.
This quick action is called "handling time." High-speed videos show that the mole always uses its 11th "finger" to check out food. This is very similar to how human eyes focus on details in a scene.
The star-like nose also lets the mole smell underwater. This was once thought impossible for mammals. Mammals usually need to breathe air to smell. But the star-nosed mole blows tiny air bubbles onto objects or scent trails. These bubbles are then sucked back into the nostrils. This carries the smell molecules to the mole's smell receptors. Scientists found that the mole blows these bubbles towards food.
In the past, some scientists thought the star-nose could sense electricity from prey. They thought the mole could feel the electrical field of an earthworm before touching it. However, this idea has not been fully proven. Most scientists now believe the star-nose is mainly for touch.
Evolution of the Star-Nose
The unique star-like nose likely developed over a long time. It probably started as small bumps on an ancestor's nose. Over many generations, these bumps grew into the star shape we see today. Most moles have small Eimer's organs on their noses. One North American mole species has small bumps that look like early versions of the star-nosed mole's nose. This shows how evolution can add new parts to an animal's body plan.
The star-nosed mole is an extreme example in mammalian evolution. It might have the most sensitive touch system among all mammals. There are two main ideas about why the star-nose evolved.
One idea is that it developed because of the mole's wet habitat. Wetlands have many small insects. To eat these tiny insects, the mole needed a very sensitive nose. The soft, muddy soil in wetlands also helped. It is less rough than dry soil, so the delicate star-shaped nose could evolve without getting damaged.
The second idea is about how profitable food is. This means how much energy an animal gets from food compared to the time it takes to eat it. Star-nosed moles eat very small prey. So, they developed a way to eat them incredibly fast, sometimes in just 120 milliseconds. This amazing speed helps them get enough energy from tiny food items. It also gives them more time to find more food. The star-shaped nose is very close to the mouth. This also helps the mole eat food super quickly.
Modern Uses of Star-Nosed Mole Research
Studying special animal systems can help us understand more general things. The mole's amazing star-like nose might teach us about touch in other animals, including humans. We don't know much about how mammals sense touch at a tiny level. The star-nosed mole could be a key animal for studying touch, like how the fruit fly is used in genetics.
Understanding the mole's fast, precise touch system could help create new types of artificial body parts. Also, the mole's speed and accuracy could inspire the design of smart machines. These machines could have amazing sensory abilities, just like the star-nosed mole.
How the Star-Nose Helps Find Food
Animals try to get the most energy from their food in the least amount of time. This is called optimal foraging theory. Star-nosed moles can eat very small prey extremely fast. This means they can eat foods that other slower animals wouldn't bother with. Having their own food category is a big advantage.
Right behind the 11th ray of the star, the mole has special front teeth. These teeth act like tiny tweezers. High-speed videos show that the mole uses these teeth to pick up small prey from the ground. The 11th rays spread apart as the teeth move forward to grab the food. This suggests that the special teeth and the super-sensitive star likely evolved together. They help the mole find and eat small prey very quickly. The ability to quickly find and eat small prey was probably the main reason the star-nose evolved.
Images for kids
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A specimen from the collection of the Muséum de Toulouse
See also
In Spanish: Topo de nariz estrellada para niños
