Archive for February, 2012
This is epic. I had little, well to be honest NO, idea has to how whales slept. I always assumed they were similar in physiological terms to dolphins, which I believe have half their brain (one hemisphere) sleep at a time whilst the other half is awake. However, this photo, and some articles and videos I just looked up, shows a pod of sperm whales in deep sleep whilst floating vertically just under the water surface.
It seems that scientists only first learned of this, and documented it, back in 2008 in the waters off of northern Chile.
For scientists have filmed whales drifting off to sleep for the first time.
A pod of six sperm whales was captured on film floating motionlessly and upright just below the surface of the sea off the coast of northern Chile.
The footage confirmed data evidence from 59 tagged sperm whales around the world that they snatch brief periods of sleep lasting about 12 minutes at a time during their ocean voyages.
Here is the footage the scientists captured.
“Many mammals show species-typical sleeping behaviour, such as dogs circling before lying down, lending support to the idea that sperm whales sleep during these drift dives.
“One exciting aspect of this finding is that it suggests that they actually might sleep in a fashion that we recognise as similar to sleep in terrestrial mammals. The sperm whale behaviour we describe seems to allow normal-looking quiescent sleep, possibly including REM sleep which has never been clearly observed in any cetacean. “
It also raises the possibility that the sperm whale – the largest toothed whale which can be 60-feet in length and which has the largest brain of all whales – may also be capable of dreaming.
Dr Patrick Miller of the University of St Andrew’s School of Biology’s Sea Mammal Research Unit
This research shows that sperm whales may completely ‘switch off’ for short lengths of time in the wild, effectively having ‘cat naps’ whilst they perform slow rhythmic dives. The research team think this study shows that sperm whales could require less sleep than other wild mammals.
So I posted a few days ago about leucism and albinism, both genetic disorders that lead to the pigmentation of animals not being expressed normally, so they appear completely or partially white. Anyway, reading up a bit more on things apparently there is also a genetic disorder that lands on the opposite end of the shade spectrum at black. It’s known as melanism.
Melanism is effectively the complete opposite of albinism. Both of these genetic disorders involve the regulation of the melanin pigment in an animals cells, whereas leucism affects all pigment types not just melanin.
Unlike albinism, melanism is the result of a dominant gene. So just carrying a single allele for this gene leads to the expression of melanism in one’s phenotype, (they appear darker). From an evolutionary point of view this adaptive trait becomes selected for when darker individuals have a higher fitness compared to lighter individuals and are better camouflaged to either elude predation or aid in the capture of prey.
1. The peppered moth. This species was predominantly white with black dots, giving it a peppered appearance, before the industrial revolution. After the industrial revolution began the pollution killed off the lichen on which the moths would sit on trees to camouflage themselves. The trees then became blackened by soot leaving the white peppered moths much more visible to predators. In a very short time this white morph disappeared and a black morph, that could much better camouflage on the trees, became dominant. So melanism in this example evolved to avoid detection by predators.
2. Black panthers. These are not a specific species of their own. As it happens they are in fact a black colour variant of a number of large cat species including, cougars, jaguars and leopards. Black variants in all of these species have been documented, but most ‘black panthers’ seen in captivity will be melanistic leopards (below left). Unlike peppered moths, these cat species have evolved black morphs to aid them in hunting at night, and avoid detection by their prey items. Leopards and jaguars, specifically, are known to inhabit dense jungles in the Americas, Asia and Africa, where a darker appearance would be a great deal more beneficial than for say a cheetah or lion living in open plain environments (they could be seen from miles away by prey).
As well as being found in many wild species such as squirrels, deer, bobcats, insects, seals and penguins to only name a few, melanism is often selected for by breeders in a large number of domestic animals, sheep, guinea pigs, cows, rabbits, cats and dogs. My folks have a black labrador and black tabby cat. You can still see her tabby lines in the right light as even though the hairs are all the same black colour, they have a different shine to them.
Furthermore, something awesome I read about was that wolves that are totally black, you know those freaky ones with the epic yellow eyes, actually received the melanism from the domestic dog. The mutation first arose in the domestic dog, and due to wolf-dog hybridisation wolves gained this trait.
Here are a few more images of melanistic animals found via a quick Google images search.
The image of a woman, yes Christians A WOMAN, was found in the crosscut of a branch by a man doing some pruning in his backyard recently. Although, I’m sure the religiously inclined will no doubt see whatever else they want in this crosscut as long as it confirms their faith and can be portrayed as evidence of the miraculous!
This is awesome page put up by BBC News! It gives you an idea of how deep animals can dive, w
Icy cold, pitch black and with crushing pressures – the deepest part of the ocean is one of the most hostile places on the planet. Only two explorers have made the epic journey there: 11km (seven miles) down to the bottom of the Pacific Ocean’s Mariana Trench. As a new wave of explorers is gearing up to repeat this remarkable dive, take a look at the mysterious world that they will be plunging into.
It’s a webpage that takes you on a journey from the surface of the ocean down to the very deepest depths, and gives you information about each zone. Suss it out!
This is a picture of the largest man in the world in 1903, Big Joe.
The largest man in the world about 100 years later is probably this guy, Manuel Uribe.
On a side note: were people always that graceful in the ‘olden days’, who puts their foot up to get a photo taken anymore? And that kind of action shot for the world’s largest man too in 1903?
Posted in Biology, Evolution, Genetics, Reptiles, tagged achondroplasia, albinism, albino, alligator, dwarfism, Evolution, green sea turtle, leucism, leucistic, pigeon, turtle, white turtle on 26/02/2012 | 1 Comment »
On first appearances I’m sure the majority of us would proclaim with interest and enthusiasm, “WOW! An albino green sea turtle.” However, that isn’t the case interestingly enough! It’s actually a turtle with what’s known as leucism. According to wikipedia:
From my understanding, the best way to tell the difference is by looking at other parts of the body like the eyes (leucism can also be patchy in appearance where only some parts of the animals skin is affected). Melanin is the only pigment that contributes to eye colour (in the iris specifically), and hence why it’s possible to detect the difference between these two genetic disorders. (However, this method isn’t necessarily fool proof as I’m sure pigmentation attributed to melanin may vary a great deal across many different species, so genetic tests would probably be the only thing that is truly fool proof when it comes down to it).
In the below example using the alligator, when the eyes appear as they normally do, with grey/blue pigmentation, the animal is most likely leucistic, and if it has pink eyes lacking melanin pigmentation then it’s an albino.
People may ask why traits like albinism or leucism still exist in the wild when surely it has little if any benefits for animals? Evolution via natural selection unfortunately finds it relatively impossible to weed out traits like albinism and leucism which are recessive. That is that they aren’t exhibited by the animal (in what’s called its phenotype) unless the animal has two copies of the recessive alleles (one from its mother and one from its father). If it only has one, it will exhibit the same phenotype (it will appear the same) as would an individual without any copy of that allele.
Because of this fact, individuals who carry two alleles and appear white are likely to have a lower fitness level than other normally appearing individuals, and is thus more likely to be killed/predated prior to passing on its genes. However, because individuals can carry a single recessive allele for albinism or leucism without any changes to its appearance, if it ever mates with another individual who is carrying a single (or two) recessive alleles then offspring may be produced carrying this phenotype. Similar to genetic disorders in humans such as cystic fibrosis or sickle-cell anemia.
On a side note, during my volunteer work in Queensland at Mon Repos with sea turtles, I would often find white hatchlings. Unfortunately, the majority of them normally didn’t make it out of their shells and died in the burrows as a result of other genetic defects they also carried (they often had contorted bodies, and one I found had no eyes at all). In once case I even found twin albinos sharing a single egg shell. Sometimes you’d find abnormally large eggs an these would have two yolks or embryos in them. It was rare enough that they would actually develop at all, let alone develop and both be albino or leucistic.
Looking back I wish I’d had a closer look and could’ve worked out whether they were carrying albinism or leucism! I might have to rummage through my turtle photos and see if I can find some images of them.
Secularism: wanting our government to treat all people without privilege or discrimination based upon religion, race, etc.
How could anyone be opposed to this unless they are already privileging from, or having their ‘enemies’ discriminated against, as a result of the current setup? One may wonder why religion is often terrified of secularism, then again…
What do you think? Is there any justifiable reason to be afraid of a purely secular government? And what are reasons for which others fear such a setup?
For me, all too often I hear, see, read about Christians, for example, who are abhor secularism because they feel it takes away ground they’ve already won, it ‘treads on their freedom’. From my point of view though, if you were truly Christian and all for equality you have nothing to fear int he slightest. The only reason you could possibly be annoyed is that you will now be only a level playing field with everyone else, instead of having the upper hand, whether it’s access to children in state funded schools or access to government like in the UK where 26 seats on parliament are reserved for bishops.
I find it offensive when religion so often portrays itself as altruistic and so adamantly pro equality, yet it only seems this is the case when said equality comes at someone else’s cost.