Gray seals responsible for killing harbour porpoises

 

Scientists were baffled when harbor porpoises (Phocoena phocoena) started washing up on Dutch coastlines with horrible mutilations on their bodies; original suspects included fishermen, collisions with boats or some new type of apex predator but after several years enough data was collected to finally identify the culprit which shockingly was the grey seal (Halichoerus grypus).

A group of Belgium scientists who were studying the porpoise carcasses noticed that some of the puncture wounds appeared to mirror the teeth marks of grey seals; they therefore decided to study photographs and autopsied carcasses of grey seals from 1081 seals between 2003-2013 which had washed up on Dutch beaches.

They ended up finding numerous signs that grey seals had been responsible for the injuries on the harbor porpoises, some had scratches along their bodies that matched grey seal claws and large chunks of blubber had been bitten away; yet visual evidence was not enough to fully suggest that the seals were the cause of the porpoises demise and so the scientists decided to see if they could find seal DNA in the porpoise carcasses to further back the evidence that the seals were the culprit.

Collecting DNA from the carcasses proved a difficult task as seawater would wash away many traces of culprit DNA but eventually DNA was found which matched that of a grey seal. The lesions from where the DNA was collected also showed hemorrhaging suggesting, the injuries were caused whilst the porpoises were alive and that therefore the seals did attack the porpoises and were not scavenging on them prior to a attack by another predator. 

The results showed that in at least 17% of porpoise deaths grey seals were the cause, this meant that grey seal predation is one of the top causes of harbor porpoise deaths in this region alongside, by-catch (when they become caught in nets used by fisherman and often suffocate as a result) and disease. 

The scientists are still unsure why grey seals have started to prey upon the porpoises but theories include developing a taste for them whilst scavenging fishing nets for by-catch.

What do you think about this finding? Would you have suspected grey seals of this predatory behavior? It is worth noting that at around 2.5m grey seals are the largest predator in the area studied and are therefore capable of taking down large prey items but generally we have always accustomed them to a strict fish diet, until now that is.

To read the original paper click here 

Bird-like lungs found in Iguanas, is this further proof that reptiles and birds are more similar then we think?

A new discovery by Collen Farmer of the University of Utah demonstrates that iguanas have lungs alike to those found in bird species which, were believed to be present only in birds as a way of combating the high energy levels needed for flight but as iguanas do not fly, this can no longer be the case.
Mammals including humans, have lungs that have a branched structure, when we breathe in, the diaphragm ( a dome shaped muscle under your lungs) contracts expanding your chest cavity, intercostal muscles (located between your ribs) also help to further expand the chest cavity allowing for expansion of the lungs; this causes air to enter your body via the nose and mouth, down the trachea (windpipe) and into the lungs, once inside the lungs the windpipe divides into bronchial tubes (one for each lung), which divide into bronchioles and then further into alveoli. The alveoli are covered in capillaries (blood vessels) which connect to the arteries and veins of the bloodstream. When we breathe out the diaphragm and intercostal muscles relax reducing the amount of space in the chest cavity and therefore lungs causing air to exit the body in the opposite way to which it entered.

 

 Note: Cardiac notch is where the heart sits against the lung.

For birds, iguanas and some other reptiles including alligators and monitor lizards, they have a lung system in which air flows through a one way loop, they lack a diaphragm and have air sacs instead which fill a role similar to bellows to pump air through the lungs. When a bird breathes in they need inhale twice to get air to pass through the whole respiratory system  instead of singularly like mammals, on the first inhalation air enters the trachea then into the air sac below the lungs (caudal air sac), the bird then exhales and the air enters the lungs and into the bloodstream; the bird then inhales a second time forcing air from the lungs into the second set of air sacs in front of the lungs (cranial air sacs), the bird then exhales and the air leaves the body via the trachea.

Note: Posterior air sac = Caudal air sac, Anterior air sac = Cranial air sac.

The team of scientists at Utah university discovered this method of breathing in iguanas, by using a surgical scope to observe the lungs of live specimens as they inhaled harmless smoke from a fog machine. They then used 3D x-ray imaging images to make a computer model showing airflow which matched closely the observations seen in the real iguana lungs which showed that shapes and angles within the lungs of iguanas direct air in one direction. This discovery therefore points to the possibility that this method of breathing came from a common ancestor of crocodiles, lizards and dinosaurs (birds), further suggesting that reptiles and birds are more alike then we originally thought.

 3D x ray images of the iguana lungs

What are your thoughts on this new discovery? Do you think that birds and reptiles will be reclassified into a new group together in the future? As always leave your comments in the box below and thanks for reading.

To view the original article click here 

To view a previous post regarding the similarity between reptiles and birds Click here 

Animals live in a colourful world but they all view it differently

We live in an enthralling world full of natural beauty and colour but not every species of animal views colour in the same way; this is because the colour of an object is determined by the sensory capabilities of the viewer and therefore is not set like size or weight. What we perceive as colour is actually the result of light hitting photorecepetors at the back of our eyes; these specialized cells then covert these light signals into brain signals that allow us to see the visual image. These photoreceptors can be catorgorised into two types rods and cones, the rods aid us with scopic (nightime vision) whilst cones are responsible for colour vision.

Inside the human eye there are 3 types of cone cell with each responding to different wavelengths of light i.e. short, medium and long and are named blue, green and red cones respectively, these cones are each triggered differently when light hits the eye and depending on how each cone responds for example the red may be stimulated more than green, the signals are then sent to and interpreted by the brain which builds the final colour image.

 

As humans have three types of cone cells we are said to have trichromatic vision however, most mammals have dichromatic vision and have only two types of cone cell which is blue and green sensitive. Old world monkeys and apes display trichromatic vision like us but new world monkeys appear to have sex linked colour vision, this means that females display trichromatic vision whilst males are dichromatic, some such as tamarins have females that can be both dichromatic and trichromatic. It is theorized trichromatic vision within new world monkey species may aid with foraging as red/green items will be easily seen or for same species communication whilst, dichromatic vision may be useful in areas of low light or when foraging for camouflaged food.
Most animal species such as reptiles, birds, some insects and fish can have tetrachromatic vision having four cone cells with the fourth cone cell being used to receive UV light but it is not uncommon for some to have 5 or more.

Note the dog view represents dichromatic vision whilst human represents trichromatic.

Note the bird vision represents tetrachromatic vision.

Now we can clearly see that tetrachromatic vision generates a colour spectrum wider than our own does this suggest that the more cone cells a animal species has that it should see and be able to discern between a wider colour range? Well a recent scientific study aimed to put this theory to the test using a marine species called the mantis shrimp  (Haptosquilla trispinosa) which has 12 cone rods and should therefore be able to see far more colours than us humans can. To test this theory the scientists studied the shrimps ability to be able to discriminate between two colour types but instead of being able to easily differentiate colour difference the shrimps displayed worse results than what would be seen in humans, this was because the shrimp had developed over time a new way of perceiving colour signals, in which the photoreceptor outputs are sent directly to the brain instead of being pre-processed where, they are compared with a 'pre-set' template of colours to produce the final image; this process is thought to benefit the shrimp by less time being needed to process the image being received leading to a more rapid visual response.

The reality of the situation is however that as we will more than likely never be able to physically see through the eyes of other animal species, we will never really know or fully understand what it is like to view the world through their eyes but regardless of that the world is still a beautiful place when viewed through our own eyes and maybe we should therefore take more time to stop and admire its beauty more often.

As always I'd love to hear from you guys about this article, please feel free to add a comment below and thanks for reading.

Swallowed Alive! Has reality tv reached a new low?

You might think that the picture above shows a man who loves and appreciates snakes, yet Paul Rosolie is actually face to face with the snake that he expects to eat him.
Paul Rosolie is a documentary film maker from southern Peru who has previously won a award from the United Nations Forum on Forests for a short film called Unseen Forests in 2013. Now though he plans to be eaten alive by an anaconda Eunectes murinus, by wearing a snake proof suit and then forcing the snake to release him. Not much more information is provided regarding the purposed documentary which is due to be aired on the American Discovery Channel on the 7th of December and there is always the chance that this could be a publicity stunt based hoax but if the show is due to go ahead it will create waves of anger within the herpetology (reptile) field and animal lovers worldwide whilst demonstrating a new low in both scaremongering and non educational shows which now dominate channels that are meant to be educational.

This documentary holds no educational value as we already know about the workings of the snake digestive system in much detail and it's this knowledge that demonstrates exactly why this procedure will be harmful to the snake. Anacondas are constrictors and therefore rely on killing their prey by slowly squeezing them reducing the ability for the lungs to expand and by increasing pressure on the heart; obviously this can not happen in this situation which means that the anaconda most likely will have to be force fed the man. Now in some instances in captivity where a snake has not fed and is physically deteriorating as a result force feeding is often undertaken as a last resort, this process is not only stressful for the snake as it is an unnatural position to be placed in but has the potential to harm or even kill the snake if not performed correctly with such an over sized meal; this is because in order to consume prey bigger then itself the snake has a specialized breathing tube which it positions over a meal during feeding allowing it to be able to continue breathing. The body suit as shown in the picture above appears to have many areas that protrude outwards which will make it more difficult for the snake to swallow and could potentially damage the digestive tract of the snake especially if Paul moves whilst inside the snake.

Note: The fleshy tube is the breathing tube or glottis.

Now even if they managed to get the anaconda to swallow Paul whole they then have the next problem of getting him back out; now we can not just let nature take its course as the snake proof suit will prevent the natural breakdown of such a large meal preventing him from being passed out in the traditional way as I think we all can agree that there is no way a fully grown adult man will ever pass through a snakes cloaca. This leaves just two options regurgitation or surgical removal both of which are extremely harmful/stressful to the snake. Regurgitation within snakes is a difficult and stressful process in which undigested food from the esophagus not stomach is brought back up, with anacondas it places even more stress on the snakes body as they loose precious bodily fluids which can not easily be replaced. Surgical removal will require first anesthetizing the snake which carries its own risks and then cutting a hole wide enough in the snake for Paul to be removed which could cause substantial damage to the snakes body or be too large to be stitched back together ultimately resulting in the snakes death.

Is entertainment really worth the suffering of such an amazing animal which has adapted of thousands of years to be a amazingly efficient hunter, I most certainly do not think so, what do you guys think? As always feel free to leave your comments below.

Baby superb fairywrens start learning whilst still in the egg.

 It was generally thought that the immature brains found within the embryo had limited learning capabilities but we have since learned that even within our own species, prenatal learning and recognition occurs with the baby responding to the mothers voice from around 32-34 weeks.
A study on superb fairywren Malurus cyaneus hatchlings in 2012 demonstrated that chicks that had learnt a specific sound from the mother whilst still in the egg received more food as, the parents knew they were feeding their chicks instead of cuckoo chicks which often target this species.
Building upon this knowledge the same scientific team led by S.Kleindorfer at Flinders University, decided to test if the chicks responded to different sound stimuli whilst inside the egg; they achieved this by using a ipod with a speaker and played recordings of three different types to eggs which were around 9-13 days old. The three sound choices were female superb fairywren incubation calls, contact calls of neighboring winter wrens and the control sound which was white noise. For those readers who may not know, the control within a experiment is basically the unaffected/unchanged group i.e. in this experiment they wanted to see if there was a reaction to specific sounds, by having a sound that theoretically produced no sound that was recognizable to the chicks and was ignored by them but they responded to the other sounds, they could suggest that it must be a response to those sounds and not other external factors.

Whilst the sounds were played the heart rates within the eggs were monitored, this is because a lowered heart rate demonstrates that the embryo was paying attention within the egg. This allowed them to discover that the embryos lowered their heart rates when both the female superb fairywren incubation and winter wren calls were played but not for the white noise, which suggested that they were attempting the learn the differences between the calls of different species compared to that of their own. They also discovered that they also reduced their heart rate in response to a new superb fairywren call that they had not previously heard, suggesting that they can recognize voice characteristics of different individual superb fairywrens. To read the original article click here. To view the published paper click here.

I found this article very intriguing, to think that such advanced recognition capabilities are being discovered in such young embryonic life stages clearly demonstrates that even as we develop within the safety of the womb or egg; nature is still giving us the essential tools we need to survive once we enter the world, as the ability to not only recognize the sounds of those that play a parental role but also those of the same species provides an essential level of protection which the young needs whilst, they develop the tools they need to become a adult and survive on their own maybe, we should revise the saying your never to old to learn to include your never to young either.  

What do you think? Please feel free to leave your comments in the box below.