CyberDodo and the Alligators (1-39)
Are Alligators crocodiles? Here is a case file to help you find out more about these animals with...
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Why have we started this case file by asking this question? Because the answer is that there are more than a thousand and as there are so many different species, they can be found almost everywhere on earth. There is so much diversity among bats that many books would have to be written to describe all of them!
So let’s have a look at their common features. After rodents, they are the most numerous mammals on earth, and can be divided into 2 sub-groups: microchiropterae and megachiropterae. From the words ‘Micro’ and ‘Mega’, we can conclude that ‘small’ bats fall into the first category and ‘large’ ones fall into the second category. Generally this is true, as the largest of the small species are bigger than the babies of the bigger species!
Is this clear?
The unifying features of most microchiropterae are that they feed on insects or small animals, move around with the use of echo-location (we will look at this in more detail later), they have no claws on their front fingers and their ears have a specific shape. However, take note that 3 species of microchiroptera must be classed among vampire bats, since their staple food is blood. The average size of the microchiroptera is about ten centimetres (the smallest ones are less than 5 centimetres long, while the largest ones are more than 15 centimetres long) and there are more than 800 species.
Megachiroptera generally feed on fruit and live in hot countries (Africa, Asia and Australia). Some of the chiroptera can truly be described as ‘mega’ because their wingspan is more than 150 cm and they weigh more than one and a half kgs! However, the smallest ones are not even as long as 15 centimetres and have a featherweight of less than 5 grams. There are less than 200 species of megachiropterae.
The word ‘diversity’ could have been invented just to describe bats!
What unique features do bats have?
Let’s start with their capacity to fly – they are the only mammals that can fly – indeed, they are so talented that they could compete with the best pilots! They have a unique morphology and, unlike birds, their wings have no feathers, but consist of a skin membrane (called the patagium).
Their wings are just like a superhero’s cape that is attached to the sides of their body and they have very large hands. This unique apparatus means that bats have an extraordinary flight path (for information, the ‘flight path’ of an aircraft is the space in which it can move safely = altitude, speed, manœuvre, etc.) and they are just as skilled as helicopters, since they can practise stationary or slow flight. But the art of floating or flying (by flapping their wings) is no secret to them at all.
Another feature of most bats is that they are active at dusk or at night. How do they find their food? There are 2 sub-groups that have developed different strategies - the Microchiropterae and the Megachiropterae. Megachiropterae fly mainly with the use of their sense of sight and smell, similarly to many other animal species.
But the microchiropterae are different - Nature has endowed them with an extraordinary tool which man only started to be able to reproduce in the 20th century: echolocation. What is it?
In answer to this question, imagine this scenario – it’s a very dark night, mosquitoes are flying around and a bat wants to eat, will it be able to do so? Yes, it can, very easily, with its eyes closed! To do what would be a feat for a human being (particularly since we are considered as prey by mosquitoes!); the microchiroptera simply uses its ‘sonar’ device.
Concretely, echolocation is the capacity that bats have of ‘seeing’ with the use of sound. They send out ultrasound rays in the direction of their targets and if the target is directly in front of them, the rays will bounce back, giving an extremely precise representation of their environment.
In fact, there are 3, the transmitter, the receiver and the decoder. Depending on the species, it generates ultra-sound (between 10 Khz and 120 Khz) through its mouth or nose and picks up the echoes with its ears. This is where the third organ comes in: the brain. It will analyse the information in a fraction of a second and thus enable bats to ‘see’ at night.
Although man has invented a mechanical sonar device in the 20th century, he is still far from attaining the level of miniaturisation that Nature is capable of, since even microchiropterae weighing less than 5 grams have sonar.
Just to give you an idea about the importance of echolocation and its ability to detect things, a bat can ‘see’ a hair in total darkness from several metres away...
How do bats reproduce?
If the species lives in a country that has cold periods, it will have to hibernate. A female that will have mated in the autumn will keep the male sperm in its genitals throughout winter. Ovulation only occurs during spring, when climatic conditions are favourable for young ones to be raised.
Sexual maturity is attained between the first and the third year, depending on the species. After 2 or 3 months of gestation (or even up to 8 in some cases), bats generally give birth to only one young, however, some of them can even have 2. Females breastfeed their young.
How long do bats live?
It differs between the species, but they can live for up to 20 or 30 years!
Why do some bats hibernate?
Very simply because they cannot find food any more when temperatures drop. Insectivore species living in temperate countries therefore hibernate, but how do they do this?
In short, everything slows down!
Their heart beat reduces from several hundred to a couple of beats per minute, their body temperature reduces to a few degrees; they barely breathe and are totally still.
They start off their months of hibernation by grabbing hold of a surface and letting their bodies relax. The weight of the bat’s upper body pulls down on the tendons connected to their talons, which lock into position and the bat’s weight keeps them closed.
But the success of hibernation, in other words, waking up in good shape in springtime, depends on several factors, particularly enough food to accumulate the required fat reserves as well as the use of a good quality shelter which can be a cave, an attic, a mine or even an old tree trunk, so long as it is a quiet place, with a temperature and a humidity that is as constant as possible.
A quiet spot... Another increasingly difficult challenge!
This is because the conditions a bat requires for safe hibernation are not generally available due to man’s lack of respect for Nature. Also the damage caused to the environment seriously affects bats.
Like many other species, they are suffering as a result of the disappearance of their habitats (this word is in the plural because they change their living place according to the seasons and their activities), the intensive use of chemical products in crops, houses (structures), food resources (consumption of treated insects), etc., the invasion of their territory by man and the associated disturbance (noise, light, automobile collision, etc.), as well as the influx of domestic animals (cats are one of the biggest predators).
Throughout their life cycle, bats are animals that are very sensitive to human activity and numerous species are currently endangered.
Why should we protect bats?
This is relevant because even though today bats are protected by several international conventions (notably the Berne and Bonn conventions), people are scared of them and will do everything in their power to hunt down and even destroy colonies that they may find in their houses (attics, garages, caves, etc.).
It must be said that the legends and myths about bats are not always very nice (Dracula, etc.) and the fact that certain species feed on blood has reinforced these fears. However, Batman the superhero demonstrates their qualities.
And they have many qualities!
Do you know that a small bat can eat several hundreds of mosquitoes in one night? The University of Florida, situated in Gainesville (http://www.ufl.edu/), built a ‘bat house’ in 1991 as part of an environmentally-friendly anti-mosquito campaign.
It has been highly successful, with more than 200,000 occupants and the bats operate with such efficiency against mosquitoes that there is no need for any chemical treatments. Sadly the University of Florida bat house was unable to accommodate the huge number of bats and it collapsed in August 2009.
However, it was rebuilt before the end of 2009 and the bats were able to return home again.
Should we be scared of bats?
We hear and read a lot of fantasy information about them, that they drink blood, that they are dangerous, that they grab your hair, that they carry diseases, etc.
What is it about them then? Firstly, as we have seen in this case file, there are only 3 species that feed on blood, they live in South America and only rarely attack people. Bats are generally not dangerous and they do not grab people’s hair. Even though when they fly around us it seems as if they are surrounding us, we are actually being surrounded (attacked?) by a whole swarm of mosquitoes, which bats can get rid of and this is how bats can help us.
With regard to illnesses transmitted by bats, it is true that some of them can be carriers of a particular form of rabies. How can we protect ourselves against this? It is extremely simple - under normal conditions it is impossible to be in close contact with a bat, so if you see one on the ground or it allows you to come near it, it may be sick and you should not touch it.
In conclusion, this case file shows that bats are important for biodiversity and more than useful for mankind and it is up to each and every one of us to protect them. How can we do that?
By doing simple things such as letting them have access to places, not disturbing them during their hibernation period (a bat that is woken up during hibernation may die), respecting forests, rivers, not doing massive concreting, not switching on lights when there is no need, avoiding chemical products which can kill them just as much as they hurt us…In short, behaving responsibly so that future generations can also be able to live on a habitable planet.
Bats and humans = the same battle of life, fought by CyberDodo the Defender of Life!
To see the cartoon on bats, click here
To see the game on bats, click here
To do the quiz, click here
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