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Toxn

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Scaly footed gastropod - aka that snail living in a hydrothermal vent and producing an iron shell and scales.

 

Trichobatrachus_robustus.JPG

The hairy frog - notable for a unique defence mechanism which involves forcing the bones of its fingers through the skin to produce makeshift claws.

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I found some amphiuma carcasses in my yard a couple years ago when the pond valve broke leaving the pond dry. They are pretty strange. Giant predatory salamanders with reduced limbs that fertilize internally are rather interesting features for a creature found in Dixie. 

A_means1HILL.jpg

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This is campoletis sonorensis.  It is a parasitoid wasp that preys on armyworms.

 

Like many other Ichneumonid wasps, it carries a virus that suppresses the immune system of its hosts.  This prevents the eggs it lays from being rejected by the host's immune systems.  The eggs hatch in to wasp larvae, which then eat the armyworm from the inside out, they grow up, and the beautiful circle of life continues.

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There are lots and lots and lots of parasites.  Many of them have much more complicated reproductive cycles than the wasp above.

 

This is a guinea worm:

 

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They infect a freshwater copepod, which then gets swallowed by a mammal, then they hatch in the mammal and grow, emerge through the skin of the mammal and get back into the water where they infect new copepods.

 

Drac_life_cycle.png

 

The type of guinea worm that infects humans is rapidly going extinct.  I'm pretty happy about that.

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Is there an evolutionary preference for laying larvae in other organisms and if so, why dont more species do it? 

Define "preference". Plenty of organisms practice parasitism in one form or another, and laying eggs in some poor creature is certainly a form of parasitism.

The problem for parasites is that they often become locked into one host, as the benefits of targeting a specific organism tend to drive the parasite towards specialisation.

 

You can see this progression by comparing wasps which use this approach. The paper wasps (really broad term, but anyway) construct nests which are then used to house their developing larvae. The larvae, in turn, are fed chunks of prey by the adults. Having no real reason to specialise (meat is meat, after all), the paper wasps tend towards non-specificity when selecting prey.

 

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I've been stung so badly by these things :mellow:

 

The mud daubers and potter wasps go further: ranging from generalist snatchers through to specialists who target individual species. Their strategy for providing food to their larvae - creating a nest, laying an egg in it and then provisioning it with a paralyzed prey animal - obviously lends itself towards more specialisation by dint of having a particular volume of nest to fill and a correct ratio of paralyzing venom to dish out per prey animal. 

 

Meanwhile, the Ichneumonid wasps go all the way - by laying an egg in/on a living host and thus getting the food and shelter sorted in one go. As such there is a strong incentive to become specialised, as 'matching' the host's size and metabolic quirks will provide a massively improved chance for your offspring to make it. This has lead to the Ichneumonids becoming exquisite living guided missiles - in some cases to the point where they parasitize parasites:

 

https://www.youtube.com/watch?v=GCo2uCLXvhk

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I had the opportunity to meet and speak with the artist and famed T-shirt peddler Ray Troll who is kind of a big thing up here in Alaska. From him I learned that there was such a thing as a saber toothed salmon which grew up to 6-9 feet in length and weighed over 400 pounds. It also had giant fangs sticking out of the side of its mouth. They lived 4-5 million years ago.

 

sabretooth.jpeg

 

sabertooth-salmon.jpg

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Why do birds do anything? Energy efficiency.

 

 

How could it possibly be more efficient to begin sinking, and then have to generate enough lift not only to overcome weight, but also enough to re-accelerate upwards to continue the periodic motion?

 

In any case, flying is for chumps:

189598_199430550078642_6847298_n.jpg

 

Chelychelynechen quassus; a flightless duck from the island of Kauai known from subfossil remains.  Reconstruction by Carl Buell.

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How could it possibly be more efficient to begin sinking, and then have to generate enough lift not only to overcome weight, but also enough to re-accelerate upwards to continue the periodic motion?

 

In any case, flying is for chumps:

189598_199430550078642_6847298_n.jpg

 

Chelychelynechen quassus; a flightless duck from the island of Kauai known from subfossil remains.  Reconstruction by Carl Buell.

it's more efficient because of how muscles work. The more continuous work you do, the more energy will come from anaerobic metabolism. So short bursts of activity, followed by a cool-down to allow re-oxygenation of tissues, is better.

 

In any case, this seems to be one of these things where there is a specific weight/size range where bounding flight works. Outside of it you see flapping-and-gliding.

 

Edit: Hahaha it looks like I'm way off the mark and this is actually a super complex field of discussion:

http://www.google.co.za/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CDIQFjADahUKEwjn1uDFrvvHAhUOWtsKHTfsChA&url=http%3A%2F%2Fwww.dtic.mil%2Fcgi-bin%2FGetTRDoc%3FAD%3DADA402713&usg=AFQjCNFGh-VOUGpuWnS2enWh3TtCbuIuGw&sig2=0cXYbUGNNTSWqR4eZGIncw&bvm=bv.102829193,d.d24

http://www.brendanbody.co.uk/flight_tutorial/bounding.html

http://jeb.biologists.org/content/202/13/1725.full.pdf

http://www.sciencedirect.com/science/article/pii/S0022519385801648

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Troglobites have always been interesting.

 

The regression of vision in caves seems like a pretty quick evolutionary process, which seems to suggest that vision comes at a high energy cost. Well, according to this new paper, the energy cost of eyes is nearly 5-15% of a fish's total energy budget. Being able to save large chunks of energy like that by losing your eyesight should help you pass your genes along a whole lot better.

 

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The Mexican cave fish and its eye-ed relative, the Mexican tetra. These were the subjects to the study. 

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