Female rodents use their powerful nose to select a male partner

“I SMELL a rat,” it’s less likely you’ve wondered about whether a rat smells you, as it turns out, rats and other rodents have pretty sharp sniffing ability. Different scientific research have proved that female rodents use their powerful nose to select a strong male partner.

Tracking odor trails is a crucial behavior for many animals, often leading to food, mates or away from danger. Meanwhile, after a powerful earthquake struck parts of Turkey and Syria on 6th February this year, two weeks ago we covered a special article about rodents.

Today scientists around the world are thinking about how to use African giant pouched rat because rodents are primarily olfactory animals with robust and versatile olfactory learning abilities.

African giant pouched rat have been shown to have stereo olfaction, the ability to localise an odor by comparing the signals across nostrils. In the savannah, in order to survive all animals must detect, interpret and respond to an array of sensory information in their immediate environment.

Animals need to locate and assess the quality of food, detect and avoid predators, and identify mates and competitors.

Animals can gain information about these resources or threats, as well as convey information to other individuals, via numerous modalities, including vision and olfaction. For many mammals particularly rodent’s olfaction is most likely the dominant sensory modality because social behaviours including parent and offspring interactions, are also strongly regulated by olfactory signals.

Rodents are mammals which are characterised by a single pair of continuously growing incisors in each of the upper and lower jaws. Most rodents are small animals with robust bodies, short limbs and long tails.

They use their sharp incisors to gnaw food, excavate burrows and defend themselves. Today scientists say rodents form 40 per cent of all mammal species and they are native to all major land masses except for New Zealand, Antarctica and several oceanic islands. Rodents are extremely diverse in their ecology and lifestyles and can be found in almost every terrestrial habitat, including human made environments.

Rodents generally have well developed senses of smell, hearing and vision. Nocturnal species often have enlarged eyes and some are sensitive to ultraviolet light. Scientists say the sense of smell, or olfaction, is the special sense through which smells or odors are perceived.

The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones and plays a role in taste. Zoologists say animal with the most robust sense of smell is very smart since various olfactory receptors detect different odors.

Olfactory receptors work to detect odorants resulting in the sense of smell, these receptors are in millions and mainly concentrated at the nasal cavity’s back area where they form an olfactory epithelium. Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue.

Epithelial tissues line the cavities and surfaces of blood vessels and organs throughout the body.

Scientists say among rodents, cells of epithelial tissue are tightly packed and form a continuous sheet around their nasal cavity. The nasal cavity or nasal fossa is a large air filled space above and behind the nose in the middle of the face, each cavity is the continuation of one of the two nostrils.

The two nasal cavities condition the air to be received by the other areas of the respiratory tract of a rodent, owing to the surface area provided by the nasal conchae the air passing through the nasal cavity is warmed or cooled to within 1 degree of body temperature. Scientists say in addition, the air is humidified, and dust and other particulate matter is removed by vibrissae, short, thick hairs, present in the vestibule.

The entire mucosa of the nasal fossae is covered by a blanket of mucus, which lies superficial to the microscopic cilia and also filters inspired air. Scientists say through special mechanism the microscopic cilia move the secreted mucus and particulate matter posteriorly towards the pharynx where it passes into the esophagus and is digested in the stomach.

Unlike humans, many animals including rodents have two distinct and segregated olfactory systems, these are main olfactory system, which detects volatile stimuli, and an accessory olfactory system which detects fluids. Scientists say these are two main, anatomically and functionally distinct chemoreceptor systems namely the main olfactory system (MOS) and the vomeronasal system or (VNS).

It has been suggested that the MOS primarily detects volatile odorants from the environment whereas the VNS primarily detects nonvolatile odorants from an animal of the same species. It is well known that both systems can work together to a degree to detect both types of odor cues.

This is possible because among rodents there is a chemosensory organ that appears to mediate behavioural responses to alarm pheromones.

The nose houses the MOS which consists of the main olfactory epithelium, this is the primary site for the detection of volatile odorants. The main olfactory has about 10 million sensory neurons located directly in the nasal airstream with between 500 to 1,000 olfactory receptors.

African giant pouched rat are capable to do many things because their organ of the Vomeronasal System is primarily involved with the reception and decoding of olfactory cues, providing a relatively direct pathway to the main system.

Scientists say rodents have larger and flexible smelling organ with greater ability than any other mammal. Projection of the system from the rest part of their head is a unique advantage due to their structure and size which enables them to recognize and discriminate thousands of odor molecules due.

Olfaction is the dominant sensory modality in rodents, and is crucial for regulating social behaviors, including parental care. Mammalian olfactory systems are complex, remarkably precise because one odorant receptor gene expressed per cell and allow mammals to recognise and discriminate a large diversity of odorant molecules.

All this facts show rodents rank pretty high in terms of olfactory abilities because they are highly sensitive to smells, and some species have even been trained to detect odors specific to land mines and tuberculosis. Different researches have indicated that rodent are capable to identify and avoid scents from some chemical compound and go away the source.

Rodents are able to smell when predators are nearby or when they have set up in an area, this allows them to hide, and flee before they are spotted. Don’t undermine what they are capable to do, African giant pouched rat are able to detect the scents of large birds, cats, snakes, and even humans.

A smell of food sources will attract rodents but females use scents to select a potential male partner. This is what scientists call sexual selection, it is a procedure which consist of male to male competition and mate choice by female.

Among rodents through mysterious procedure female choice, it is a unique mechanism which enables a female to have some control over who fathers her child even after fertilization.

Inside the savannah, a beautiful female will use the sex pheromone to find a strong male, According to the scientists, female rats will be drawn to the scent of a potential mate. Scientists say the action is not born out of love, it is trap to get a strong male for strong offspring who are capable survival in the savannah.

This is very important because in the savannah mammalian maternal care is essential for offspring survival, mammalian paternal care is rare. This is most likely because the costs associated with paternal care increase energy expenditure which cause loss of mating opportunities and reduce chance to survival.

However, scientists say paternal males can significantly influence offspring growth, survival, and cognitive and behavioural development. Paternal care is rare in rodents, but can have significant consequences for offspring fitness, suggesting a need to understand the factors that an individual consider before mating.

This trick is proved when the number of females in a colony declines, reproduction numbers dip, which means rodent populations decrease in size. Rodent brains are smaller than human brains, according to research, rodent brains are similar in structure and function to the human brain.

Researchers have proven that their vision and processing abilities are advanced enough for them to recognise 3-D objects despite changes in size or orientation.

There are several natural rodent behaviors that indicate a certain level of intelligence, for example, African giant pouched rats have multiple methods of communicating with one another. They can talk through their characteristic squeaks and chirps and some vocalisations, known as ultrasonic vocalizations are so high pitched that humans can’t hear them.

African giant pouched rats have other form of communication include urine, which contains pheromones that can spread important messages, and body language, such as tail drumming, which can indicate aggression. Rodents are social creatures and are known to live in communities.

Within these communities they display social behaviors such as grooming, sleeping together and playing. Due to this unique ability of African giant pouched rat, they have also been known to display aggression toward unfamiliar rats.

To work successful at any time, rodents use their powerful noose with high sense of smell which is capable to pick small particles in the air and effectively sniff them while sending clear message to the brain which translate them. From this stage a rodent will use the direction of wind to detect the specific source of food is located inside the vast grassland of Serengeti national park.

To work toward this hidden location which may in the middle of a huge bush, rodents employ their whiskers or vibrissae which are larger and longer than other hairs around the mouth.

Scientists say whiskers grow out of very sensitive tissues which are able to detect small movement in the air, this ability helps African giant pouched rat to recognize its way to the intended location without a clear sight. Whiskers or vibrissae hair is usually thicker and stiffer than other types of pelagic hair but, like other hairs, their shaft consists of an inert material known as keratin which contains no nerves.

Omnivorous rodents use their whiskers for hunting, are able to pick heart beats of a prey which help its brain to picture out size and spice type of the intended prey.

As they work toward their prey at night, rodents use whiskers to detect obstacles and avoid aggravating their prey until when they reach a good or strategic position for an attack.

A rodents has more rod cells than cone cells in the retina of the eye, these are photoreceptor or light sensitive cells, and they function to convert visible electromagnetic radiations or light into signals which stimulate biological process.

Rodent’s eyes are equipped with two photoreceptor cells which are rods and cones, each of these cells contributing information used by the visual system to form a representation of the visual activities. Cones cells are wider which work as color detector while rods cells are narrow and they are responsible for light as they are distributed differently across the retina.

This shows that African giant pouched rats have more light sensitive cells packed tightly in the fovea which is the most sensitive area of the retina, this means their eyes need little amount of light to see something in the darkness than human eyes.

A rodent has what is known as a Tapetum lucidum, this is a reflective layer of cells positioned behind the retina.

This means light entering into the eye’s will be absorbed by either the rod or cone cells, light that passes through the retina and the photoreceptor cells is reflected back by the Tapitum lucidum.

This action happens while the light sensitive cells have a second chance to absorb the light waves, in effect doubling the effectiveness of their night vision. Scientists say rodent’s eyes do not glow in darkness, but they contain a special reflective coating that will reflect even moonlight.

Scientists say the reflective layer results in the eerie or eye shine which is seen when a light shine on rodent’s eyes at night is also found in other mammals in the savannah except rhino which its eyes doesn’t have eye shine.


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