One animal that is
specially adapted to its environment is the Chinese Alligator. When an animal
is adapted it means that it has features which enable the animal to survive and
thrive in its environment. The Chinese Alligator is widely distributed
throughout China, mainly along the Yangtze River and some of its tributaries.
They can be found in rivers, lakes, ponds, streams, swamps and marshes. Chinese
Alligator habitat is in the subtropics which have a mixture of weather
featuring strong winds and humidity, thunderstorms and heavy rain. The average
temperatures are 30 degrees Celsius in the summer months and 10 degrees Celsius
in the winter.
Alligator’s skeletons have many adaptations to help them to survive in their environment. As you can see they have four limbs which are very short and stocky and this is because they spend most of their time in water so therefore they don’t need to be able to run to catch prey or be able to move fast on land although they have adapted to be able to stretch their legs and lift their bodies right off of the group so that they can run at a fast speed for a very small distance so that they can escape danger and the main reason is so that they can protect their eggs from predators because they actually nest on land. They also have an extremely long coccygeal vertebrae/tail, this is extremely powerful and is adapted to their environment because it makes them incredible swimmers and helps them to catch prey because it gives them lots of power to burst out from under the water. It also makes them very fast. It also is used for protection because they can swing it around and it is very powerful so it can help them to protect their nests from other lizards and also helps them to communicate with other Alligators and to assert their dominance. It is also very powerful and muscular to help Alligators because they use it to help them dig out their burrows and also to gather emergency water reserves for their burrows. They have a very distinctive and strong skull, this an adaptation to their environment because this is their main weapon when hunting and it has to be strong not only to help them hunt but so that they can communicate and it is used in one of the main methods of Alligator fighting which is where they smash their heads together, they will fight like this to assert their dominance and also to compete for mating etc. It is also adapted to hunting because Chinese Alligators skulls are adapted to hunting because they contain lots of power which helps them to catch and hold onto their prey even in difficult conditions such as under water. Another adaptation to their limbs is that although they spend most of their time in water and are amazing swimmers, they actually don’t have webbed feet; this is because they actually dig burrows in water banks which I will go on to talk about in more detail later on. This is seen more clearly in the front feet than the back because they front feet are more commonly used for digging these burrows. This is seen in the image above. One more adaptation is actually the size of the animal; the Chinese Alligator is the smallest species of Alligator growing to about 5ft on average, now this is an adaptation to its environment because the main types of prey that the hunt are fish and small mammals so therefore there is no need for them to be large in size and also it would make it more difficult for them to hunt because it would make it a lot more difficult to ambush their prey because there would be a lot more to try and hide and so therefore they made stand out more and it would make it more difficult for them to hunt.
Next I am going to
talk about how the Chinese Alligators sensory systems have adapted to their
environment. Their eyes, as with all crocodilian species have adapted to being
able to see underwater, they have done this because they have an extra eyelid
which is called the nictitating membrane. It is semi-transparent and covers the
eyes when the Alligator is submerging underwater, however their eyes have never
adapted to actually being able to focus underwater because they do not actually
need to be able to thanks to their other senses. Alligators eyes are also
placed on the sides of their head which is an adaptation so that they have
excellent peripheral vision (the only place they can’t see is right behind
them) and this is good because in their environment they need to be able to see
around to be able to protect themselves and especially their young from
predators and it also makes it much easier for them to spot and catch prey.
Another adaptation to the Alligator is that their eyes and nostrils are located
on the tops of their heads so therefore this allows them to fully submerge
their entire body underwater which helps them to camouflage while they are
hunting for prey. This is seen in the picture to the left. Alligators have also
adapted to have special flaps of skin which closes of their ears and nostrils
whenever they go under water in order for them to remain water tight. They also
have a special flap called the Palatal Valve which closes off the back of the
throat to stop water from getting into the throat, stomach and lungs so
therefore this shows how they really are specially adapted to living in water
because it helps to allow them to stay under water for long periods of time. A
normal dive can last 10-20 minutes but a alligator can stay under water for up
to two hours if at rest and if it is cold water then they can stay fully
submerged for up to 8 hours! The palatal valve shutting off
the entire throat allowing them to remain water tight and submerge underwater
for such long periods of time. Alligators eyes have also adapted to hunting in
dark conditions because not only can it be dark under the water but also for
them to have become such amazing predators they hunt not only in the day but
also at night so they have eyes similar to a cats in that they reflect light
which enables them to see in the dark. Alligators also have very good hearing
and they have a small muscle in the middle ear which is called the stapedius
which geckos also have and this helps them to suppress strong vibrations so
that their ears are less likely to become damaged from loud noises such as
animals yelping. Chinese Alligators upper and lower jaws are also covered with
sensory pits known as Dermal Pressure Receptors which respond to the slightest
disturbances in the surface water, detecting vibrations and small pressure
changes in the water, making it possible to detect prey, danger and intruders
even in complete darkness.
‘Alligators are ectotherms, instead of staying warm by having a high metabolic rate, as mammals and birds do, they regulate body temperature primarily by behavioural means.’ (Thorbjarnarson and Wang , JT and XW, 2010. The Chinese Alligator: Ecology, Behavior, Conservation, and Culture. 1st ed. Unknown: Unknown.) There are many ways in which Chinese Alligators have adapted to be able to thermoregulate in the conditions in which they live and there are many techniques which they use including avoiding temperature extremes, moving around to and from sources of heat and opening or shutting their mouths in order to lose of hold in heat (if their mouth is open then they are trying to lose heat). The main way in which Alligators have adapted to be able to thermoregulate in their environment is by building burrows. Alligators live in environments with changing weather conditions which is unlike most other crocodilians which live in places where the weather remains relatively hot all year round. So therefore by building burrows this means that Chinese Alligators are able to hibernate for 6-7 months of the year which would be the winter months, if they were not able to do this then they would die out because they get all of their energy from heat so if they aren’t warm enough then they would become unable to hunt and so would starve. The burrowing systems also come in handy when it is too hot because it not only means that the Alligators can escape the sun and cool off but it also means that because of the clever way they construct these burrows that if the river/ area of water they were living in was to dry up then it is likely that water would remain in their burrow so they could live in there until the rainy season came. (Alligators can go for up to a month without eating so they wouldn’t starve.)
The next area of
adaptation that I am going to talk about in a Chinese Alligator is how their
skin has adapted to their environment and this can be linked back to how
Alligators have adapted to be able to thermoregulate in their environment too. Alligator’s
skin has adapted in many ways but the main way it has adapted is that it is
made up of very tough scales which are used for protection against other
animals, other alligators and the harsh environment. These scales shed
individually which means that they have a minimal effect on the alligators live
and do not interfere with things such as hunting and appetite unlike with other
reptiles. The fact that they shed also helps to keep them strong and in good
condition and helps to heal any wounds quicker in order to stop infection. On
the head of and Alligator the skin is actually fused to the bones of the skull
which is because the head is the area that takes the most damage on a crocodile
because thrashing prey can easy damage the head and also when alligators fight
they tend to smash their heads together and snap at each other’s faces so this
helps to make the skin a lot stronger and to protect them. The way that the
adaptations of the skin link back to thermoregulation is that Alligators have
blood-rich bumpy scales all along their backs which act as little solar panels
so therefore if a Alligator is feeling to cold it will go up onto the bank and
lay in the sun and the heat will be
absorbed through all of these panels and then once they get too hot they will
go back into the water and this will cool them down because it will stop the
heat absorbing scales from absorbing any extra warmth. The only exception to
this is that sometimes when Chinese Alligators have a really hot summer the
body of water that they are living in may actually become hotter than laying in
the sun would be so therefore this is when they would use their burrows to cool
down because it keeps them out of the sun so their isn’t as much heat for the
scales to absorb on their backs. Another adaptation of the skin can be linked
back to the skeletal system of an Alligator and it is that just under the
scales all over an Alligators body are tiny plates of bone called Osteoderms
which provide the Alligators which an extra form of protection and acts like an
armour. These are what form the small bumps all over their skin. They need this
armour because they live in a very harsh environment and share it with other
alligators and this means that they will fight and due to the strength of alligators they need
to have an incredibly strong skin so that it is hard to penetrate otherwise
they would not be able to survive. It also protects them when they are catching
prey because when they catch their prey the prey tend to thrash around and many
of their prey species will have sharp claws, teeth, hooves and so they need to
have some form of protection against this and Osteoderms are the main reason
they have been able to survive such a long time and why they are such an
amazing, specially adapted creature which has been around for about 180 million
years. The
picture on the right shows a close up of Osteoderms.
So overall you
can see that there are many ways in which Alligators are specially adapted to
their environment and without these adaptations it is highly unlikely that they
would have survived this long. These adaptations could be seen as the reasons
why Alligators have been around as long as they have and survived through so
much.
