The … organic materials in [some] meteorites probably originally formed in the interstellar medium and/or the solar protoplanetary disk, but was subsequently modified in the meteorites’ asteroidal parent bodies. … At least some molecules of prebiotic importance formed during the alteration.
Amino acids are the building blocks of life as we know it. They can be formed from abiotic (non-biological) chemical reactions (in a jar with electricity for example). It’s been known for a while that amino acids can be found on comets and asteroids, but now this fascinating article suggests that a lot of the chemical reactions that created these precursors to life happened on the asteroids themselves. Then when the asteroids bombarded the Earth, the seeds of life were delivered. More details here.
Leonid meteor shower seen from orbit. Image credit: BMDO/APL via NASA JPL.
This, of course, is just one of several hypotheses about the origin of life on Earth: livescience.com outlines seven.
This video from NASA (via physorg.com) includes a nice little section showing the movement of charged particles (cosmic rays) through the Sun’s magnetic field. What’s really neat, is that the Voyager spacecraft (now 33 years old) have discovered magnetic bubbles at the edge of the solar system that make the particles dance a little. It’s a wonderful application of the basic principles of electricity and magnetism.
After the joy of playing around with microscopy and staining last fall, it’s no surprise that someone has taken the science of staining and specimen preservation and turned it into art.
Iori Tomita has done an amazing job at making visible the internal organs of the specimens.
Using a method that dissolves an animals natural proteins, Tomita is able to preserve these deceased animals with striking detail–highlighting the finest and most delicate skeleton structures.
To further enhance the visual appeal of these ornate skeletons, Tomita selectively injects different colored dies into hard bones and soft bones to create a 3-d effect. Without the addition of the dye, the animals remain translucent.
Transparent specimen by Iori Tomita. Note the exquisite detail (via Stinson (2011)).
Tomita’s website has some excellent photographs, and there appear to be two books available from Amazon.com.jp. More pictures can be found online here and here. Lisa Stinson at Wired has more pictures and details on the method.
To follow up my own attempts at a fish anatomy lesson, I asked the people at the Gulf Coast Research Lab’s Marine Education Center to include a dissection in their program for our Adventure Trip. They chose squid.
Squid are nice because they’re mostly soft tissue and the organs are fairly easy to identify. They’re also quite charismatic, which piqued the students’ interest. These squid were going to be used as bait, so I didn’t feel too badly about using them for science.
Squid and reference diagram.
Once again, our guide, Stephanie, was an excellent teacher. A good time was had by all, even though it was a bit gruesome.
An excised beak.
I would have liked to have a little more time to draw some diagrams, but I don’t think my students would have had the patience. It was the Adventure Trip after all, and they’d much rather spend the time outside.
As for the future, I like this note about squid dissection:
… this … is a tactile experience. You may want to explore this aspect through sensory activities, written descriptions, poetry, and/or artwork. Encourage students to experience the many textures found inside and outside the squid’s body. Moving fingertips along the suckers is suggested as well – the suckers do not scrape or hurt if you are gentle with them.
–Center for Educational and Training Technology, Mississippi State University: Squid Dissection
This quote comes from a Mississippi State website, which also has a great set of calamari recipes in addition to dissection instructions. I’m always in favor of an interdisciplinary approach; food-preparation rather than purely dissection.
Finally, the University of Buffalo’s Biology 200 class has some excellent, labeled pictures, for reference.
Tiny quantities of dysprosium can make magnets in electric motors lighter by 90 percent, while terbium can help cut the electricity usage of lights by 80 percent.
There has recently been a bit of a furor over the fact that, currently, China produces 90% of the world’s rare earth metals. Special properties of these elements are making them extremely important in a lot of high-tech and alternative energy technologies.
Fiber-optic cables can transmit signals over long distances because they incorporate periodically spaced lengths of erbium-doped fiber that function as laser amplifiers. Er is used in these laser repeaters, despite its high cost (~$700/kg), because it alone possesses the required optical properties.
The rare earths are so chemically similar that they’re lumped together in one corner of the periodic table, which is why they have not been used a lot until now. Only recently has their influence on elecromagnetic systems been discovered. Wikipedia has a good list of the elements with some of their uses.
The rare earth elements.
Many people are worried about one country controlling so much of a single resource, especially since China cut its export quotas earlier this year. Fortunately, rare earth metals are found in places other than China, and, as the demand continues to outstrip supply, it’s just a matter of time for high prices to to bring more mining and recycling projects into production.
Extruding sediment from the corer into the sieve. Dashed lines indicate where the piston and metal rod extend inside the barrel of the corer.
On the first morning of the Coastal Science Camp, between dip netting and seining at the estuary, we tried sampling beneath the seabed using a little coring device which I seem to have to forgotten the name of.
Some students were quite excited about the chance to sample beneath the surface of the sediment. Student displays the sampling device is in his right hand.
Usually, they can see the little holes in the seabed where the benthic macrofauna live, but not this time. All the sediment pouring into the Mississippi Sound from this spring’s swollen rivers had made the waters too turbid to see through. So we were coring blind.
The corer is simply a metal (stainless steel) barrel with a rubber piston inside. The piston is connected to a handle at the top with metal rod. To sample, you put the tip of the barrel at the sediment-water interface and push the barrel into the sediment at the same time holding the handle steady to keep the piston from moving into the sediment. Holding the piston steady provides a little suction on the inside of the barrel, which helps the barrel move into the sediment, and keeps the sediment in the barrel when you pull it out. However, it does help to put your hand on the bottom of the barrel as soon as possible to keep the sediment from falling out, even if that means sticking your hand into the sediment itself.
Keeping you hand on the bottom of the barrel keeps the sediment from falling out before it gets to the sieve.Vague layering is visible in the sediment.
Once you’ve recovered the sediment, you extrude it into a sieve. Sometimes you can see a little layering in the extruding sediment, but we did not take the time to try to interpret it since our focus was on finding benthic fauna.
The sieve’s mesh is pretty coarse, so anything sand sized or smaller is washed out as you gently rock it back and forth in the water. We did not find much. Mostly small pebbles. Without being able to see the seabed our sampling pattern was pretty random.
Small pebbles in the sieve.
The more persistent groups (the class had been broken into groups of two or three) did find a couple things, including a polychaete, which is a segmented worm.
A polychaete.
They also turned up a small, clawed, lobster-like organism:
We also found the burrow of an unknown organism, surrounded by a clayey cast. It looked very much like some of the fossilized burrow casts we saw at Coon Creek.
Burrow, with surrounding cast.
This type of sampling was not everyone’s cup of tea, however. Fortunately, the water was shallow and warm, so a good time was had by all.
Some groups were less successful at finding benthic macrofauna than others. They had other things on their mind.
A groin strains to hold back the longshore drift. It is, as always, only partially successful.
It was about 1.5 kilometers from the Research Lab to the estuary where we spent our first morning sampling (overview of the trip is here).
Elevated beach house.
Walking along the beach to get there, we could see the beach houses to the right of us, across the narrow road of East Beach Drive, standing tall on columns to keep them above the reach of the storms. According to Stephanie, our guide, the storm surge from Hurricane Katrina in 2005, reached awfully close to the tops of the columns. The research lab, which is not elevated, lost an entire building to that hurricane. Indeed, much of the coast is still recovering from Katrina’s damage.
The white sandy beach, on the other hand, looked beautiful, which was a bit odd. After all, how did it survive the storm? Furthermore, when you think about it, this beach is located behind a string of barrier islands, which protect the coast from the full force of the waves coming out of the Gulf of Mexico, so how come there is enough wave energy to maintain a sandy beach. The relatively calm waters should allow finer grained sediment, like clay and silt, to settle out, and this area really should be a marsh. The answer, it seems, is that this is an artificial beach. Every few years, thousands of tons of sand are dumped along the coast to “replenish” the beachs.
Without beach replenishment the beaches would revert to salt marshes like this one.
This coastline really should be a tidal marsh, like the one we found when we got to the estuary. These Gulf-coast salt-marshes are fronted by a relatively short version of smooth cordgrass (spartina alterniflora), backed up by the taller, and more common black needlerush (Juncus roemerianus Scheele) .
Longshore Drift
Now, if this is a low-energy environment that allows silt and clay can settle out of the water column, where does the sand go so that it has to be replenished every so often? It is gradually moved along the coast by longshore drift.
Longshore drift moves sand along the coast in the direction of the wind. Image via the USGS.
Waves hit the beach at an angle. As they break, the turbulent swash pushes sand up the beach at the same angle as the movement of the waves. As the wave retreats, the backwash, drawn by gravity, pulls sand perpendicularly down towards the water. The net effect, is that sand gradually moves down the coastline with each swash and backwash of the waves.
Since dumping tons of sand is expensive, engineers try other things to prevent the sand from running off down the beach. Someone, a very long time ago, had the great idea to build a wall sticking out from the beach to impede the sand in its unwanted migration. This type of wall is called a groin (or sometimes a groyne in polite company), and it does stop the sand. In fact, the sand builds up on the upwind side of the groin. Unfortunately, it does not stop the longshore drift on the downwind side, and that results in the erosion of a bay on that side.
A groin impedes longshore drift. Note that the waves approach the beach at an oblique angle.
Pufferfish
Beaches are also great places to find random things washing up. We lucked upon an unusually large pufferfish (family: tetraodontidae). It was quite puffed up. It was also quite dead.
Pufferfish.
Pufferfish are famous for being extremely poisonous. According to the National Geographic page on pufferfish, their tetrodotoxin over a thousand times more poisonous than cyanide, and there is no known antidote.
