How To Identify a Cactus

The columnar saguaro cactus.  Note the huge column like shape and ribs lined with spines traversing from the bottom to top.

Cacti are one of the most diverse and interesting plant families in the plant kingdom.  Cacti are native only to North and South America but are prized worldwide by plant enthusiasts.  I once worked with a PH.D who was from England but came to the United States specifically to work with cacti.  While you can go to just about any botanical garden in the world to observe cacti, the Southwestern United States and Mexico are probably the best places to observe cacti in the wild (in North America at least).  Within the United States, cacti can be found in the wild in just about every state.  Where I grew-up in Iowa, every once in awhile I would come across plains prickly pears growing in a dry prairie.  Now, living in the Southwest I come across cacti every single day.  The Sonoran Desert is loaded with all kinds of different cacti ranging from the 50 foot Saguaro cactus to the six inch tall pincushion.  Cacti are really not that difficult to identify, at least to the genus or "group" level.  Just about anyone can learn the major groups of cacti simply by looking at three major traits; the shape, ribs, and spines.

Barrel cacti in foreground.  Named after their barrel like shape.  Barrel cacti also have ribs lined with spines.

Shape is possibly the easiest and best way to categorize a cactus.  The most common cactus group is the prickly pears.  These cacti have stems that are sectioned into flat, pear or pancake shaped pads.  The overall prickly pear plant is joined together by these pads typically forming a shrub shape.  Cholla cacti are similar in that the plant is made up of sections, but instead of these sections being flat and pear shaped, they are cylindrical, and the overall plant also is shrub shaped.  Barrel cacti are barrel shaped.  Columnar cacti such as saguaros form tall columns. Tiny pincushion cacti are small and often shaped like an actual pincushion.  Hedgehog cacti are sort of like small columnar cacti that only grow a few feet tall at most, with the small stems bunching together.

A cylindrical cholla cactus section.

Ribs are the next important way of identifying a cactus.  Saguaros and other columnar cacti have long ribs or pilleates that stretch from the bottom of the cactus to the top.  Hedgehogs and barrels also have ribs.  Pincushions, prickly pears, and chollas do not have ribs. 

Prickly pear cactus with flat pear shaped sections.

Lastly spines.  Spines don't always help us distinguish between different groups of cacti but are extremely useful in determining the actual species of cacti.  A few spines like the tiny hairlike glochid are only found on prickly pears.  Glochids are the tiny spines that get stuck in your skin and have to be taken out with a tweezers.  Pincushions typically have tons of white spins which helps give them a "pincushion" like appearance.  Spine color, number, and shape are essential in learning to distinguish specific species of cacti.

Hedgehog cactus

Pincushion cactus.

Bringing Back the Dinosaurs... Sort Of...

Picture of a hadrosaur based off of findings from the dinosaur mummy "Leonardo".

In our last post we discussed how it has recently been discovered that some dinosaur fossils contain remnants of soft dinosaur tissue. In this post we will discuss the discovery of a fossilized dinosaur mummy.  Specifically, this dinosaur is a hydrosaur, or a duckbilled dinosaur, that died and was quickly buried in sediments before it could decay.  The burial process mummified the dinosaur, preventing decay and eventually the mummy was fossilized.  This dinosaur mummy is different from say human Egyptian mummies in that the dinosaur is actually fossilized and rock.  Egyptian mummies are simply well preserved tissues of the human that died.  As a result of the dinosaur mummy fossilizing, all of the parts of the dinosaur present in the mummy are still present today in rock form.  The process of fossilization of dinosaur mummies is exceedingly rare and have only been found a handful of times.  The awesome thing about mummies is that they preserve the soft tissues such as internal organs or skin which normally decay away long before any scientist can observe them.  The difficulty with fossilized mummies though is the fact that all of the soft tissues are now actually rock, which obviously is extremely difficult to dissect.  The documentary movie "Secrets of the Dinosaur Mummy" shows how modern day paleontologists "dissected" Leonardo without hacking him up.  The movie is a great demonstration of real scientists doing real science.  As a result of the "dissection", the scientists were able to find out all kinds of interesting biology about the dinosaur.  Huge changes in what we believe about dinosaurs in how they look and how their body functions have come about because of the investigation shown in this movie.  Also interesting, since the movie has been filmed, soft tissues like we talked about in our last post also have been found in Leonardo. 

Secrets of the Dinosaur Mummy
 

Actual fossilized dinosaur mummy "Leonardo".

Is Jurassic Park Possible? Bringing Back the Dinosaurs

Dinosaur soft tissue found in a fossilized T-Rex leg bone.

Is Jurassic Park really possible?  For nearly twenty years scientists have been telling us that the science behind the movie Jurassic Park is possible in theory, but not really possible in practice.  Why?  No one has ever or would ever be able to find intact dinosaur DNA from ancient fossilized bones, or mosquitoes for that matter.  Oddly though, about the time the movie was coming out, a paleontologist discovered the remains of some organic soft dinosaur tissue in a fossilized dinosaur bone.  How in the world would tissue survive such long periods of time and the fossilization process?  The answer to that question is that no one really knows, but several scientists working independently of each other have been able to verify the presence of dinosaur tissues in fossilized bones.  Organic molecules, including blood cells, have been found and confirmed in these specimens.  These samples open up a totally new area of paleontology and biology that has previously never been open for scientific examination before.  For example, through the examination of protein sequences, specifically collagin, scientists have been able to find that dinosaurs were closely related to birds.   Several different proteins have also been found in these fossils.  These proteins may open doors to understanding dinosaur physiology such as if they were warm or cold blooded.  Currently though, the field of studying ancient tissues from fossilized specimens is still highly controversial.  Even though there has been a lot of evidence to support the existence of this tissue and that it is not simply environmental contamination, the fact remains that it is still nearly unbelievable that organic soft tissues would survive decay over such long periods of time.  Though proteins have been found, no intact DNA has been found.  This makes sense considering protein molecules are significantly more stable than DNA.  So unfortunately, the search for dinosaur DNA and for Jurassic Park continues.  But with this discovery, we will get a lot closer to determining what a real dinosaur was like and what a real Jurassic Park would be like.

http://www.smithsonianmag.com/science-nature/dinosaur.html

In my next post I will discuss another, even more recent dinosaur finding which is even more amazing than this discovery.

Time To Plant Gardens In The Sonoran Desert

October in the Sonoran Desert means the start of a very long and productive growing season in the garden.  I have already planted garlic, green onions, carrots, beets, and lettuce.  I am planning on planting peas, tomatoes and potatoes very soon.  Most of these garden plants should grow through May.  Only tomatoes and potatoes will require a little frost protection if it does freeze this winter.  Typically I find at my house it freezes about two out of every three winters, but never for more than a few hours at a time.  I normally do not grow tomatoes during the winter but am giving it a try this year.  If they survive through the winter they should produce heavily March through July.  I am also planning on planting potatoes above ground in straw and compost, I'll post more on this at another time.  The earlier everything is started the more productivity we can get out of the garden.  If we wait a week or two it will be to cool for plants to grow very quickly, greatly reducing productivity.  If we start earlier, the bugs eat everything.  I am still trying to find a good solution to bugs eating all my new sprouts.  

We have had two years of drought which has been rather hard on gardening here.  This summers monsoon season broke that drought at least for the near future.  Fortunately, it is expected that this will be an El Nino winter, which often means more rain for the Southwest.  Even with irrigation it always seems that the garden grows best with rain.  

Bacteria: They're everywhere, and they're not your enemy

Bacteria are absolutely everywhere.  On the floor, on your desk, in the air, on you skin, in your stomach, and on absolutely everything else.  There is basically nothing that doesn't have bacteria in or on it.  Well, that is unless you cook it for long enough at a high enough temperature.  But we're talking about uncooked things here.  Us modern humans often thing bacteria is the enemy.  We like to make sure everything is perfectly cleaned with antibacterial soap so we feel safe.  Unfortunately, this is a big fat lie, antibacterial soap does not make us perfectly safe.  In-fact, it really isn't safe in itself and isn't really that great of a cleaner.  Fortunately, the fact that antibacterial soaps aren't that great and that they probably shouldn't be used is probably a very good thing. 

So first off, why is antibacterial soap so bad?  There has been a lot of research showing negative negative health consequences of antibacterial products.  Negative health consequences include neurotransmitter interference, increased allergen sensitivity, and immune system response.  I am not sure how conclusive a lot of this research is but there is a lot of it out there.  There is also good potential that antibacterial soaps with the antibacterial agent triclosan in them are mutating natural bacteria into bacterial superbugs that are resistant to antibiotics. 

Secondly, bacteria isn't as scary as you might think.  The fact that bacteria cover nearly everything is actually a good thing and only a very small percent of those bacteria are actually scary.  For example, dirt is absolutely loaded with bacteria.  But, if you were to eat dirt you probably would not get sick from all the bacteria.  The reason for this is because the bacteria in dirt is environmental and not necessarily infectious to humans.  Of course, there is some infectious bacteria in soil but it is a rarity relative to all the other bacterias.  Some research even suggests that eating a little dirt will help boost your immune system, but...  I don't suggest you do that.  We probably all tried a little when we were kids.  Bacteria that naturally lives in dirt lives there because it eats the stuff in dirt.  The bacteria in dirt does not normally live in or infect humans because it does not eat the stuff in humans.  The type of bacteria we have to worry about are infectious bacteria.  Infectious bacteria infects humans because they eat the stuff inside of people!  Typically, we come in contact with infectious bacteria through other humans, or infected water or food.  This is why we must wash our hands and not sneeze on everything or stay home when we are sick! 

No matter how hard and how many times you clean yourself with antibacterial soap, you are never going to rid yourself of bacteria, and that's a good thing. Your skin is normally covered with bacteria that helps keep your skin healthy.  Your digestive tract is filled with all kinds of bacteria that also keep you healthy.  Probiotics have in recent years become increasingly popular as people have discovered their positive health benefits.  Things like fresh yogurt and sauerkrout are loaded with the healthy lactobacillus bacteria which are one type of probiotic.  Lactobacillus bacteria are shown to improve the health of both the digestive tract and skin.  Probiotic bacteria can actually prevent us from getting sick.  Removing these probiotics from the body can have negative health consequences.  So, bacteria are friends, not enemies to be feared.

What Makes a Chili Pepper Spicy?

The chili pepper was first cultivated and bred for its spiciness in Central America, hundreds of years before any part of the rest of the world enjoyed it.  During this time, ancient Americans spiced all kinds of food with the chili.  In the southwest United States, Native Americans would gather wild chiltepine chilis and protect the plants for future use.  Aztecs were said to enjoy hot cocoa spiced with chili peppers.  When explores from the Old World began visiting North and South America in the 1500's they brought the chili to the rest of the world.  Now, the spiciness of the chili pepper has captured the taste buds of nearly the entire world.

It is amazing how the spiciness of the chili has been utilized in nearly every cuisine possible.  Even if a recipe is not made with the spice of chilis many people will put some sort of spicy sauce on it.  Think about Tabasco Sauce. people will put it on just about everything.  There is probably someone that puts it on there cold cereal in the morning.  The odd thing is, spicy flavor is painful and for some reason people like the pain (myself included).  Enjoying the spicy pain is a learned taste and some people can build-up quite a tolerance.  At least for decades, if not for centuries and millenniums, people have been trying to breed the next spiciest chili pepper.  It seemed for years the habanero held the record for spiciest chili.  In recent years a number of chili's have claimed to be the spiciest in the world.  Recently, the ghost pepper, also known as the naga bhut jolokia, from India held the title of worlds spiciest chili.  Now the trinidad moruga scorpion pepper holds the official Guinness World Record for spiciest chili. 

The secret to the chili's spiciness is the molecule capsicum.  This molecule is secreted by the white tissues holding the seeds inside the pepper.  Capsicum binds with pain receptors in the mouth responsible for detecting heat, therefore giving the spicy heat chilis are known for.  The body then responds by increasing perspiration, raising heart rate, and releasing endorphins.  Capsicum also has been shown to kill certain types of cancer cells and may indirectly aid weight loss.  In the wild, birds love spicy chili's, and mammals generally hate the spiciness (except for some humans of course).  When birds eat chili's the seeds pass through their digestive tract undamaged and can therefore germinate and grow if deposited in an ideal location.  The chewing and digestive tract of mammals however digests the seeds, preventing them from passing through the digestive tract.  This is exactly why chili peppers were spicy to begin with.  Caspicum deters mammals from eating them and to encourage birds to eat them, thus allowing the perpetuation of chili plants.  Cultivated varieties of chili's however are increasing in spiciness simply because humans are selectively breeding only the spiciest chili's in order to produce an even spicier chili. 

How to Identify a Rock

Gneiss.  A banded foliated metamorphic rock with coarse grain.

As with anything, such as plants, birds, or animals, rocks can be quite difficult to identify.  There are however, far fewer rocks to identify world wide than there are living organisms.  At a local scale there may be only one or two major rocks that need to be identified while there may be several dozen species of plants or birds.  On top of that, there is likely whole lot of rocks of the same type at a particular location which helps aid identification.  Plants of particular species may be few and far between while birds and animals fly or run away before you can ever get a good look.  So rocks may be one of the easiest things to identify in any particular habitat.  That doesn't always mean they are easy to identify though.  It is fairly typical for someone to just flip through page after page of a field guide trying to identify a rock, bird, or plant.  Then, after flipping through the entire guide realizing you couldn't find what you were looking for.  Likely the species is in the guide but you just didn't know what you were looking for.  There are several things you can do to help narrow down your search for a rock, these include color, texture, and structure.

First color.  Is the rock light, medium, or dark colored?  Of course these are generalizations and the rock might be pinkish or tan or brown.  But, even if it is pinkish it is likely a light colored rock such as granite, quartzite, or possibly rhyolite.  The rock may also have both dark and light specks through out it.  If the rocks are sort of an even "salt and pepper", with approximately even amounts of light and dark, it would be considered medium in color, such as diorite.  Even light colored rocks will have some dark specks in them or dark colored rocks some light colored specks.  The key is determining the overall generalized color of the rock. 

Granite.  A coarse, light colored igneous rock.

Secondly consider rock texture.  Is it fine grained where you can hardly see any crystals such as with the dark colored basalt or light colored rhyolite?  Is it coarse grained where you can easily see individual crystals such as with light colored granite or dark colored gabbro?  Other rocks may have lots of holes in them such as scoria or pumice.  These holes are a result of lava quickly cooling and forming air bubbles called vesicles. 

Third, what is the overall structure or pattern of the rock.  Does the rock show irregular banding patterns such as gneiss, or no pattern such as with granite?  Does the rock break into plates like with schist or slate?  Or are there many long parallel bands which are called bedding planes such as with sedimentary rocks like limestone. 

Limestone.  A light colored sedimentary rock that forms bedding planes.  No bedding planes visible in this picture. 

Also, narrowing a rock down to igneous, metamorphic or sedimentary can help a lot.  Igneous rocks are volcanic in origin and have interlocked crystals that range from coarse to fine.  The crystals have flat surfaced and fit together like a puzzle with no air spaces.  Typically there is not overall structure or pattern to igneous rocks.  Metamorphic rocks are formed by heat and pressure.  They also are made of crystals that interlock and have flat surfaces.  They do however form banding patterns of light to dark, or break into plate like pieces.  This banded or plate like structure is called foliation.  Not all metamorphic rocks are foliated such as with marble and quartzite.  Sedimentary rocks do not have interlocking crystals.  They often contain fossils and form bedding planes.  Bedding planes are thin parallel bands.Sedimentary rocks are formed through the accumulation of sediments such as sand or clay that turn into rocks.

Sandstone cliffs.  A coarse textured sedimentary rock made or sand.  Individual sand crystals do not interlock.  Sandstone forms bedding planes that run parallel to each other as seen in this picture.

By narrowing your choices down using color, texture, structure as well as igneous, metamorphic, and sedimentary, finding the right rock will be a lot easier.  Here is another great resource to help identify rocks more specifically than I have done here:

http://geology.about.com/od/rocks/a/Rock-Tables.htm

Practical Biology is Two Years Old!

Yesterday, Practical Biology turned two years old!  We now have over 200 posts and for now I plan on continuing posting twice a week.  With the cool weather returning to the Sonoran Desert where I live I plan on creating some posts on hiking again.  I also hope to develop some more field guide type posts, much like what has been done on the Projects and Series bar to the right.  Readership of the blog continues to increase with over 9,000 hits on the website in the past month.  My hope is to increase readership even more.  My desire is to continue making real science accessible to the ordinary non-scientist.  I believe our entire society has much to benefit from making scientific knowledge common to the masses.  Meaningful science doesn't have to take place only at the university, it can also take place in your kitchen or your own backyard. 

So thanks to all my readers!  I want to keep producing useful information for you.  So if you have any ideas about topics you may be interested in let me know.  I'll see what I can do.  Thanks everyone!

Fall Bird Migrations: Where do all the birds go?

From grade school we are taught that birds fly south for the winter to where it is warmer and north for the summer to where it is cooler.  Of course this is true but is obviously over simplified.  Birds don't just go south or north, they actually go to specific locations.  Scientists and bird watchers have tracked the migratory movement of birds in an effort to answer the question: where do birds actually go?  By tagging birds at their breeding grounds and then tracking the tagged birds as they migrate scientists were able to answer the question.  Watch the following video to see where birds go after they migrate south from Alaska for the winter.  It is amazing how Alaska has such a huge concentration of breeding birds in the summer that populate so much of the world as they migrate south.  This leaves us with very good reason to protect Alaska bird breeding grounds in order to protect many bird populations throughout the world.  It is also interesting that not all birds actually migrated south in the study, some actually migrated north from Alaska.  I suppose they migrated north across the North Pole so they could migrate south on the other side of the world. 

The colored dots in the video represent locations where birds originating in Alaska were found as the migrated.