Charlie, you are not alone, I found NCBI unecessarily difficult to navigate when I started using it. Keep at it!

A simple question with a complex answer! There are a few things going on. First, as Reetika said, charge balance is important for protein stability, because a protein uses charged residues (as well as other factors) to fold and stay folded. Heaps of ions in solution can mask charges and eliminate or severely curtail those interactions, potentially exposing internal hydrophobic regions and reducing protein solubility.
But perhaps more importantly, water-soluble proteins have concentric "shells" of semi-ordered water molecules arranged around them, in much the same way that dissolved salts have associated water molecules making them soluble. If you add too much salt, the waters in the protein solvation shells are stripped out to dissolve the salt, precipitating the protein out of solution. This is sometimes called "salting out".

Unfortunately, I haven't heard of a method of actively cleaning up a waterway. The best plans we have here in New Zealand are based on limiting further inflow of excessive nutrient loads, specifically farm or industrial waste and municipal sewage. This might involve artificial wetlands, planted riparian strips, or sometimes active treatment using reaction beds to clarify efluent before discharge.

Other than that, the process is largely to leave the waterway to recover on its own, once sources of pollution have been curtailed. These are complex ecosystems, and cannot be rebuilt quickly. They must recover naturally to be stable in the long term, though some key species might be re-introduced artificially if the circumstances warrent.

Breaking covalent bonds does indeed require an input of energy, so releasing glucose from starch, glycogen or cellulose does cost energy. However, under oxidising conditions, glucose is utilised by mitochondria in a process called oxidative phosphorylation, which generates a large number of high energy ATP molecules (i think the number is around 37 ATPs per glucose). So, any energy loss from the storage and release of glucose is made up for many times over once the glucose is fed to the mitochondria.

Exactly why this split happened is a matter still open for debate. Our best guess is that due to large scale depopulation of ecological niches formerly occupied by reptiles, early mammals were able to radiate massively which resulted in diversification. With greater diversity comes greater chances of the more unlikely adaptations to occur and persist, and thus the mammal's successive waves of radiation following important evolutionary innovations; monotremes, which were basically out-competed by marsupials, who then were in turn displaced by placental mammals.

There are damsel flies which can move their wings in a circular motion that resembles a helicopter. Could be a tiny species, or maybe juveniles.

All excellent points. Just to expand a little bit more; when I mentioned that large mutation events happen rarely, the fact that we have evidence for them happening and then persisting across generations, implies that there have been other such events which did not persist. So perhaps it would be more accurate to say that positive selection and fixation of large scale mutations is relatively rare, as opposed to the occurrence of such mutations in the first place, which may be more frequent than we can currently determine.

In a general sense, the accumulation of mutations is a gradual process which happens over many generations. Very occasionally you get large events, like chromosomal duplication, fusion or deletion. In plants, complete genome duplication (polyploidy) seems to be fairly commonplace, less so in animals. Which specific reference to the human/chimp chromosomal change, there is strong evidence for an end-to-end fusion of two great ape chromosomes, resulting in one which eventually became human chromosome 2.

Hi Eliot,

The answer is that there aren't really any "step changes" as you describe. All evolution is gradual, over long time periods. Where we see "sudden" appearances or changes in the fossil record, the thinking is that they already existed, it's just that we don't have many data points (ie fossils!) and are simply missing a lot of information.

What exactly do you mean by halfway? I think you can describe all evolving being as halfway to somewhere and the term "transitional" fossil is really an often miss-used one.

There are a couple of ideas about how complicated structures, like wings, eyes etc can come about in a gradual manner. With specific reference to eyes, rudimentary light sensing is better than none, so there would be positive selection pressure on even half an eye. Eyes and light sensing is extremely valuable and has been independently discovered by evolution several times across diverse phyla.

For more on evolution of complex traits, see: … complexity

Feathers and wings might be a slightly different story. It is thought that feathers were first utilised as insulation, and possibly for display, kind of like fur is in mammals. It turned out that feathered dinosaurs were perfectly positioned to exploit flighted niches, so feathers became useful for something else, namely flight. Now, that might seem like a step change, but is really a gradual development based on a whole bunch of evolution that wasn't specifically selected for flight. A very successful one in this case, avian dinosaurs are everywhere today. In a similar way, insect wings were thought to be originally developed as a heat exchange organ, later repurposed for flight with massive success.

There is a common misconception here about evolution. First off, individuals do not evolve, populations do. In your post, you said that "halfway" creatures would be less fit than their more specialised cousins. If the new phenotype suddenly appears due to massive mutation, then yes you would be correct in that it would likely be out competed by its contemporaries. Generally these kind of sudden changes are referred to as genetic disorders or diseases.

However, when a new phenotype evolves, it is the whole population which changes, over generations while under selection. For example, seals and other marine mammals have altered limbs to act as flippers. Flippers did not suddenly appear on one seal, the whole population was under selection promoting efficient movement in water. Gradually, those individuals which had flipper-like limbs did better and came to dominate the gene pool. After a few thousand generations, surviving individuals would be significantly better adapted to the water, but would likely still retain some terrestrial characteristics (which is exactly what you see in seals). You can think of this hypothetical population as transitional between a marine and terrestrial animal, or you can see the fully terrestrial ancestor as transitional to the current marine one.

Both fish and human embryos develop similar structures very early on called pharyngeal arches, which in fish go on to develop into gills, while in humans they develop into parts of the face and neck. It is more accurate to say that humans and fish share parts of our developmental pathways due to common ancestry, but at no point do humans have anything remotely resembling gills.

Here is a table of abbreviations … properties

Your list goes:

Glu = Glutamate (gloo-tam-ate)
Cys = Cystine (sis-teen)
Pro = Proline (pro-leen)
Asp = Aspartate (as-part-ate)
Thr = Threonine (three-oh-neen)
Arg = Argenine (arj-en-neen)
Ser = Serine (seer-een)
Met = Methionine (meth-eye-oh-neen)

(posted in Evolution)

As a rule, cells have anti-stress mechanisms that can deal with small errors in protein coding regions. Under normal circumstances, this machinery (generally called chaperonins) promotes correct folding. A mutation that resulted in a miss-folded protein could be rescued by cellular the protein-folding machinery. In this way some mutations are masked, until the organism encounters a stressor (like heat) that is severe enough to saturate the chaperonin system and allow the mutation to be unmasked.

In addition, mutations (or more accurately, their resulting phenotype) are not always easily categorised into beneficial or deleterious because the actual effect is circumstance dependent. For example, until the arrival of humans with firearms, male elephant with the largest tusks were "most fit" due to sexual selection and advantages in fights over mates. After extensive hunting of elephant for their ivory, smaller tusk sizes are prevalent. This is because the overall fitness of having very large tusks dropped, because they were more likely to be targeting by hunters, while smaller sized tusks became the "most fit". In this way, a change of circumstances alters the fitness benefit of a particular phenotype.

Hi Matthew, a question similar to this has been asked before: … hp?id=6873

To set the matter straight, evolution is a theory, not a law. There isn't a "law" of evolution, as far as I am aware, but evolution theory draws on widely on established science, not just biology. In physics and chemistry there are many laws of the type you describe (like thermodynamics) which are applied in biological science.

Hi Euan,

The truth is that no one really knows, though we do have some pieces of a very big puzzle. Animal behaviour is very complex, so figuring out things like what you are asking has proved quite difficult. Some describe behaviour as an emergent property, which precludes a lot of reductionist approaches to understanding it. We do have some well documented examples of communication, like in honey bees, and recently I heard about dolphins having "names" for themselves and their contemporaries. These are using visual and sound stimuli to communicate, though the details are still largely unknown. Birds and fish also use sound and visual stimuli for flocking and schooling behaviour. In things like swarming insects, the thinking is that you have a complex combination of simple "hard wired" responses and pheromone regulated behaviour, producing complex things like swarms and social nests. … s-science/

Speciation doesn't necessarily require reproductive incompatibility. In the lion/jaguar example, hybrid offspring would be selected against because they would be less fit in the niches of both the lion and jaguar parents. That counts as reproductive isolation, because the hybrid offspring would tend to die out.

A great example is finches in Galapagos. They come in certain varieties based on beak size, all of which can interbreed despite being considered different species. The different beak sizes are modal; that is, there are particular beak sizes that occur frequently, and the in-between sizes occur much less frequently. This is because beak size is directly related to survival, linked to rainfall patterns, favouring niches that rely on beaks of a particular size. These finches can and do interbreed, but the intermediate-sized beaks which result are less fit than either of their parents. There is a complicating factor in this story. The arrival of humans to the islands changed the availability of food (ie there is a lot more) so all of a sudden the hybrid finches are no longer selected against. Thus, the reproductive isolation that was imposed by very stringent niche limits has been removed, at least near the settlements.

I tend to think of the term "species" as more of a continuum of fitness then a binary thing, with each population shown as a peak in the fitness landscape. Related species might have peaks which overlap, more distantly related populations might have "budded" off to form its own isolated peak. It is even possible for two species to merge back into one, as might happen with the finches.

(posted in Evolution)

As I understand it, there is a further distinction within non-coding DNA (ncDNA) that David didn't mention. ncDNA can be broadly divided into those regions which, as David pointed out, do have a known function as gene regulators, and those which have no known function.

Regulatory elements have typically been identified by high conservation of their sequence as compared to surrounding DNA; if you were to align several homologous sequences, regulatory elements stand out due to relatively high mutation rates outside those regions. The idea is that the trans elements are very much under selection, while those regions which do not have direct, sequence-dependant functions are not, so mutations accumulate more easily rather than being selected out. This stuff is what you call junk DNA, but mostly it isn't considered junk anymore. No one really has a good idea why this apparently non-functional DNA is present, or what its function might be.

One of the ideas I've heard is that it is a mechanism for generating and storing genetic diversity without needing for it to be adaptive. For instance, sometimes these regions have non-functional genes (called pseudogenes). A mutation event could reactivate a pseudogene, potentially introducing new functional diversity that would couldn't arise by sequential mutation of an active, selected coding gene.

Another idea is that having sections of what is essentially redundant DNA is a defense against insertion of transposable elements, like viruses. This is certainly a long-term evolutionary concern, as we humans have very large numbers of inactive viral and transposon remnants in our genome. You can imagine that damage would be considerably reduced if such an insertion happened in a "junk" region as opposed to a coding or regulatory region.

(posted in General Biology)

heh, yes, higher energies, lower wavelengths......bah humbug.

(posted in Plants & Fungi)

Algae are defined as eukaryotes, so they are in one kingdom. Protista is a classification that is not really used any more, it was only ever a kind of diverse catch-all term for tiny things that didn't fit anywhere else.

Algae is a similar kind of term; it covers multiple phyla with diverse structures and lifestyles, including dinoflagelates and seaweeds.

Have a look here:

(posted in General Biology)

Yes you are quite right, it has to do with the energy of the light used. It isn't a coincidence that the visible wavelengths co-occur with those within this narrow band of the electromagnetic spectrum. In both vision and photosynthesis, incoming photons are detected and utilised by excitation and subsequent relaxation of electrons. Because of the common building blocks used (eg, carbon, oxygen, nitrogen, phosphorous, hydrogen), the excitation wavelengths in vision and photosynthesis are generally in the same region of the spectrum. At higher wavelengths (ultra violet) the photons are too energetic, and would tend to break chemical bonds. Lower (infra red) would be too weak to excite electrons.

Sadly I'm with David; looks like twisted up plastic. Try burning a tiny bit of it, see if it melts. If it does, it's probably plastic.

I'm sorry I can't be more helpful than saying it's a fly, but terrific job on the photo! Poor little guy with a broken wing!

Bats are only distantly related to primates, we diverged very early in the history of placental mammals. Bats are not well represented in the fossil record, so the phylogeny is less well supported than other clades. Current thinking has put bats in same broad group as whales and horses, though again bats diverged very earlier in the lineage.

The resemblance of the bones in a bat's arm to human arm bones is not as significant as you might think; all mammals share this common limb construction, and our common tetrapod origins can even be recognised in bird limbs. The fact that you can still (kind of) recognise a hand-shape in a bat's wing is coincidence.

Resemblance isn't really a good way to try to judge evolutionary relationships, because of convergent evolution. For example, insectivorous bats are typically small and furry, just like most rodents. That these two disparate groups have some superficial similarities and behaviours reflects the evolutionary forces that are common to both groups acting on social, mammalian insectivors.

In recent years, a major driver of intelligence has been proposed as living in social groups, rather than diet. It is hypothesised that in social animals awareness of the self and recognition of a self in others is a major adavantage when attempting to gain influence or status in a group. Similarly, an ability to track and predict the reactions of others is an even larger advantage, requiring even more brain power. So the idea goes that those who could maintain larger, more closely knit social groups did better, promoting an increase in intelligence.

An interesting notion, but I'm not sure how much study has actually been done.

I don't know of any species that has such a trait, but I would hardly call my knowledge on this subject complete!

In a general sense, you are talking about sexual dimorphism; physical differences between opposite genders of the same species. In humans, males are typically bigger, stronger, and hairer. The opposite is true in other animals, with females being larger, especially in insects, reptiles and fish. With particular reference to digits, there is a well documented difference in finger length ratio between human males and females. … g.965.html

There may not be a "reason" for this, it could simply be a side effect of normal hormonal differences during development rather then a specifically selected trait. But, if finger length can be altered subtly like this, it seems plausible that fingers might be missed out all together, or extra ones grown (polydactyly is the official term for extra fingers). A missing finger would certainly not be the biggest difference between genders I can think of.

The buzzing is definitely their wings, beating so rapidly that it sounds like a buzz. Different activities would require different motions for their wings, so the sound would change depending on what the insect is doing. For those times when you can't seem to hear it, it is possible that the sound is too high, or too quiet.

These sounds are sometimes used as communication. Some mosquitoes have courtship rituals based around matching wing beat harmonics with their prospective mates. Bumble bees vibrate the flower they are visiting to knock pollen around, using their flight muscles without actually beating their wings. Honey bees use their buzz in a similar way, but as part of their communication with other members of their hive about food sources (look for "waggle dance").

That is a very strange question, and not obviously a biology question. Do you mean a regular biological micro-organism, or some kind of digital equivalent?

I think you have probably hit a major part of the explanation right there. Mitochondria are past on only via the female line, but males get the same ones. I think it is a reasonable to suggest that, from the perspective of the mitochondria, they don't need to pass on from the males, because this is taken care of adequately by the females.

In a general sense the controlled destruction of cells happens all the time, especially during development. We larger organisms use a combination of controlled cell death, replication and variations in cell size to shape and maintain our bodies, killing individual cells to increase the fitness of all the rest. Sperm are a good example of this, dying in their hundreds of millions to produce a comparatively tiny number of new offspring. Mitochondria have exchanged genes with humans, and we are essentially one organism, even though it is still possible to see old remnants of the dividing line between us. They die so the rest might live, just like our human cells will, when evolution finds a reason.

Perhaps, for example, if there were more than one line of mitochondria in a cell, there might be conflict between subtly different biochemistries of different lineages. In the arrangement we have now, the mitochondria in the female line enjoy a completely competition-free environment, promoting high genetic stability. Introducing the male line mitochondria into the same cell might introduce competition for resources, and therefore instability, which would be bad for efficient energy production. These are only hypotheticals, I'm only suggesting possibilities.

An alternative explanation is that this is the arrangement that arose first, and it stuck. Consider the entirely different genomic arrangements of the eukaryotic nuclear genes compared to the prokaryotic chromosome found in mitochondria and other plastids; the human genome is geared for genome-wide recombination across multiple linear chromosomes during gamete production. In contrast, prokaryotes typically rely much more heavily on random mutation, and have only a single, circular chromosome. Consequently the optimal methods for reproduction would be commensurately different in the beginning, and virtually impossible to change after a few thousand generations of evolution together.

Hi Carina, great question:)

First off, animal behaviour, and navigation in particular, is a comparatively poorly understood are of science. It is a huge area of research, and an animal's brain is essentially treated as a Black Box. As far as I know, no one particular navigation system has been implicated in a way that you describe, though it is known that migrating animals, such as birds, use a variety of navigation tools and cues to get from place to place. For example; magnetics fields, sun azimuth and height, stars, sky rotation, the moon and landmarks. Magnetic field sensitivity in particular can be used to cue a direction when the sun and stars are not visible, but is most useful over long distances, rather than local "equilibrium" as you term it. Having said that, magnetic anomolies such as metal deposits can be used as local land marks.

This is certainly true in some animals (mammals, birds & maybe reptiles??), but not so elsewhere in the kingdoms of life. It comes down to parental investment. From the perspective of females, each pregnancy is a major investment of resources. In the fertile life of a female mammal (for example), there is only so much time and energy available for gestation. Plus, successful breeding can often happen only once per year, so the females might only fertile for a short time. Humans are very much the exception on this as we are fertile all year round. Thus, there is no real need for females to produce sex cells in the hundreds of millions, like males do. In contrast, male parental investment is typically much smaller. This makes it advantageous for males to attempt to spread their genes to as many females as possible, hence the hundreds of millions of sperm cells produced on a daily basis. This effect is so strong, that testicle size relative to body size is a pretty good indicator of the sexual proclivities of a particular mammal. For example, male rats, which mate with many females, have enormous testes for their small body size. In contrast, animals which are typically monogamous tend towards much smaller testes. Incidentally, by this scale humans are not monogamous animals.

Having said that, other animals have very different strategies. Frogs and toads can produce thousands of eggs in a single sitting, as do many fish. These females don't have internal gestation, and typically there isn't any post natal care, so the energy investment per egg (in terms of the resources required to produce viable offspring) is much smaller.

1) No, and no, though well done for admitting your ignorance. Sexual reproduction is a method for mixing genes, and is used by multicellular lifeforms because of their increased complexity and relatively long generation time compared to single-celled organisms. For example, we humans have a generation time of somewhere between 15-40 years, depending on the individual considered. One of the most common of our commensal flora is E. coli, which has a generation time of 20 min, under ideal conditions. Think about what that means for a moment: evolution is measured in mutation across multiple generations, so if you can get through more generations quickly, you can evolve faster in response to a changing environment. We humans, along with virtually every other animal, have adopted sexual reproduction in order to mitigate the disadvantage of our long generation time. It does this by mixing genes in a process called meiosis, which basically introduces genome-wide recombination mutations, shuffling the genes from each parent chromosome into a new combination. Contrary to what you believe, this process isn't detrimental, its absolutely CRITICAL to the continued survival of most multicellular life. The benefits of sexual reproduction are so huge, that even organisms which normally reproduce asexually (like E. coli) have mechanisms for gene swapping analagous to sex.

Your "evolution of genitals problem" is a new one on me. The arrangement of genitals is a highly varied matter throughout life. Female birds, for example, have a structure called a cloaca and the males don't have a penis as such. Many fish and other marine life simply excrete their sex cells straight out into the water, in a kind of spray-and-pray approach. Lizards have things called hemipenis. Such diversity of methods strongly implies that sex is valuable enough, and universally applicable enough, to be widely adapted by many different species. That there are so many ways found to have sex by so many different animals (and plants, and just about everything else, for that matter) means that the method is almost immaterial, as long as it works.

This link is to a short article with lots of links in it to more detailed stuff

2)The question of eye evolution has been done to death elsewhere. See here:

3)You are missunderstanding the process here. Eyes didn't "blink" into existence (haha) in one species overnight. Predator-prey relationships are extremely close, and long before actual vision was evolved, the ancestors of your hypothetical predator and their prey were competing with on another to survive; one by eating the other, the other by escaping. Changes in one species in this kind of relationship immediately puts tremendous, directly applied evolutionary pressure on the other to respond. You can think of it as an arms race. If, as in your example, the predator developed a primitive light sensing strategy which enhanced hunting, the new selection pressure on the prey population would favour those individuals with effective counter measures, such as darkened pigments or maybe a behaviour to hide from light.

Consider the first (hypothetical) organism to develop a light sensitive organ. It certainly didn't do so in isolation, and, like most organisms on the planet today, it would have had relatives kicking around with it. The concept of "contingent evolutionary trajectory" tells us that evolutionary innovations occur non-randomly, even though the raw material (mutation) is basically random.

This is roughly analogous to the development of ideas in human society, including the original thesis of evolution theory; such an idea could not have been accepted before certain facts had been discovered, such as geological age and the fossil record. Once those facts were established and other conditions were correct, the same thought occurred to at least two people within a few years of one another (Darwin and Wallace). Similarly for lightbulbs, the steam engine and even really basic things like spears. In evolution, the context for a particular innovation is all of the previous evolution which has gone before it (ie the genomes carried by a population), plus the environment; in other words, any step in evolution is contingent on all of the steps before it as well as the environmental pressures the population is facing. This means that at any given time the likelihood of a particular beneficial innovation is determined by the twin restrictions of 1)those mutations which are allowed (ie not fatal) and 2)those which provide benefit, making the outcome non-random, also known as Naturally Selected. So, many different populations can independently come up with very similar solutions to the same problem at the same time. This concept was demonstrated in the lab: … experiment

Thus, your assumption about the dominance of the first-sighted is not correct. In fact, light sensitivity has evolved indepedently several times, indicating that a)vision is very useful, even if it's only a simple eye spot, and that b)the chances of the innovation occuring are likely enough for mutliple kingdoms and diverse phylums to arrive at effective solutions based on wildly different genetic and environmental contexts.

I'm pretty sure beetles don't sting, though one could have bitten you, or maybe your dad was sinply punctured by a spine. Most beetles hide their wings under structures called elytra (which are themselves modified wings) so if you could see its wings while it was at rest, the chances are that it wasn't a beetle. From your post, the "wings" you are describing could be the elytra, but without a picture, it's all guess work.

On the one hand, we are quite closely related, given that primates and carnivora are both groups of mammals. On the other hand, the branches of mammals which contain carnivora and primates diverged very early in mammal evolution; roughly 100 million years ago. So, while we are fairly closely related in a wider view, we have been evolving separately for quite some time.

(posted in General Biology)

A difficult question. The first thing that springs to mind is assembly of an artificial bilayer made from synthetic lipids.

See here:

Also, I have heard of a method where the phospholipid bilayer is broken up using detergent, separated and re-assembled by gradual removal of the detergent. I can't remember if this resulted in an intact sphere or simply in sheets, but, like David said, it won't give you a cell wall. Alternatively, you might consider using a lipposome, which seems to be relatively straight forward to make.

(posted in Evolution)

This is a website dedicated to science education, and is targeted at school-age children. The questions you have asked have been answered by our experts and answered well, in some cases repeatedly. If you cannot understand these answers, then I encourage you to learn more on the topic. Access to academic journals is (sadly) very expensive and it is inappropriate to treat this website as your personal research resource. If you are serious about asking real science questions, then I strongly encourage you to pursue them, in an appropriate setting. There are many courses available on topics like evolution and paleontology, which will not only give you the chance to learn more on the topic but (depending on the institution) you will also gain access to academic journals.

I cannot emphasise strongly enough that attempting to dismiss decades of research by linking to, of all things, a blogspot site is completely disrespectful of the process of science and the integrity of all the experts who contribute to this website. Respect is a two way street.

Dammit! I'll resist the temptation to edit out my incorrect post, leaving my shame there as an example to others.

Yes, solitary bees are known to guard their patch of flowers from interlopers.

That is a grasshopper. I don't know about how common this particular one is, but grasshoppers are a pretty common type of insect all over the world.

(posted in Evolution)

There seems to be a link between complexity and sex. This is just a rule of thumb, but in general, small simpler organisms tend to use asexual methods, while the opposite is also true. The prevailing theory says that this is because larger, more complex organisms have much longer generation times, so in order for the genes to be mixed up enough to stay diverse and competitive over multi-generational evolutionary time, sexual reproduction is the best method. Conversely, smaller, simpler organims have much shorter generation times (the bacterium Eschierichia coli's doubling time is only 20 min) so they can get away with relying on random mutations to generate sufficient diversity for evolution to occur.

(posted in General Biology)

Of course David is quite right, but only gave one answer to a very complex question.

One alternative approach is to look at genome context, which might give you clues about function; for example comparison with other genomes might reveal conserved proximity of your gene to certain know genes or regulatory elements, which can imply a guilt-by-association relationship. This is a broad-brush approach and can be most useful with large datasets.

As a masters student I was involved in a "structural genomics" project, where crystal structures were solved of unknown ORFs from Micobacterium tuberculosis. Possible functions were extrapolated from the structures by looking for motifs or conserved folds, which are not necessarily visible using only sequence information.

But like David said, it a very time consuming and therefore expensive exercise regardless of the method.

(posted in Evolution)

Yes; it was primate, with a mix of ape and monkey features, but was neither.

The split happened around 30 million years ago, resulting in the modern monkey and ape species we see today, including humans. Humans did not evolve from monkeys because monkeys are contemporary to humans, not ancestral. The common ancestor for humans and monkeys shared characteristics of both groups, but could not be called either; it was something related, but different from both modern monkeys and modern apes.

(posted in Evolution)

Not necessarily. What you are talking about is adaptive radiation on a very large scale. Simply being the most numerous is not enough to ensure the kind of world-wide dominance currently enjoyed by mammalian species. It must also have characteristics and variation enough that allow it to adapt to appropriately diverse environments. Having said that, if the ecological space is empty or just underused due to some kind of mass extinction, it doesn't take long for evolution to give rise to lots of variation to fill it up. In some sense the occupant is the winner, so which ever species can fill up the niches first usually wins.
For a more recent practical example, you can consider the cichlid fishes of Lake Victoria in Africa. This was a case of isolated lakes populated by a founding cichlid species, not an extinction event, but the principle of adaptive radiation into empty ecological niches is similar.

I would like to reiterate David's first point, because it is very important. Criticising someone's grammar or spelling can come across as a trifle knit-picky, but you shouldn't dismiss this good advice. Communication is a vital part of being a scientist, both academically and professionally, and writing like you have done there will not be looked upon favourably by anyone.

On the use of "alot" … thing.html

Looks like a fly, though I wouldn't call it a mosquito; too large and colourful! The group Dolichopodidae are the so-called long legged flies, though your picture doesn't show enough detail for an amateur bug watcher like me to identify it:)

The thing about urine is that it contains waste products. Your kidneys are remarkably efficient filters, and their job is to clear the blood. Urine is particularly important for disposing of nitrogen waste, in the form of urea, as well as extra salt and other minerals.

Now, when you are desparate for water, urine isn't a bad substitute, for a while. It's sterile (assuming you are healthy) and most definitely wet. However, because you are drinking a waste product, you will be recycling waste back into your body that it has gone to great pains to remove. That in itself is a Bad Thing, especially if you do it over an extended period. (yuck!)

In terms of the "hydration" effect, as long as the water you drink is isotonic (ie, the same or similar salt concentration as your blood) or hypotonic (much lower salt concentration) you will get some benefit even if you are drinking your own pee! If the salt or other solute concentration gets too high (hypertonic), it will actually dehydrate you as osmotic pressure forces water out of your blood, like drinking sea water.

(posted in General Biology)

Part of the reason might be that some snakes don't have sight as their primary sense. Olfaction is very important, and some vipers have heat sensitive organs. Compare this to bats, who are generally nocturnal and have reduced eye size in favour of huge ears for echo location.

But, there are populations of viruses that are found in normal healthy guts, mostly the kinds that infect microorganisms (e.g. bacteriophage). I would argue that these are very much part of our personal microflora population, though not necessarily found on the skin.

For your first question, a brief search tell me that vapourer moth larvae use a technique called "balooning" early on in the larval stage, where they extend a filament of silk very quickly out into the air to catch the wind, taking themselves along with it. Some spiders have the same mechanism.

Bumblebees definitely can and do sting!

A bot fly is very definitely an insect parasite.

(posted in Research and Careers)

Unfortunately, the salary details are probably not known be anyone on this site. A better place to go for information of that kind is your school conselor, or maybe even a biology teacher in your school. To be a teacher you typically need a teaching qualification of some kind. To teach biology at high school level you would need an undergraduate degree at least, post graduate degrees are more liekly to be required if teaching at college. As I mentioned before, you need to speak to someone with the information specific to your region.

I think the answer is that even though there is a vast amount of life in Earth's oceans, the volume is insignificant compared to the water. I don't believe changes in sea level would be observed with either sudden removal or expansion.