Texas Exhibition! Spotlight on David Crockett

As we prepare for the opening of our new exhibition Texas! Making History Since 1519, we are dedicated to helping you learn more about the great Lone Star State. So today, Amanda Norris and Pat Dietrich, youth educators at the museum, write to you about David Crockett. Just in case you missed it, check out last week’s post on Stephen F. Austin.

This Alamo defender was born in Tennessee on August 17, 1786.  Crockett spent the early part of his life in several small towns in Tennessee, helping his father at the family owned tavern. At the age of 20, he married Polly Finley and later moved with his family to a farm near the border of Alabama.

In September of 1813, Crockett joined the local militia to avenge an Indian attack in nearby Alabama. He reenlisted in 1814. When he returned from service in Pensacola in 1815, is wife became ill and passed away. He remarried a few months later and traveled to Alabama to look for land for his family. However, he returned to Tennessee and decided to live there. He became a Justice of the Peace, but then resigned to become a town commissioner.

Tennessee Legislator

During the next 13 years, Crockett served terms in the Tennessee legislature, returned to private practice, served two terms in the United State House of Representatives, but was defeated in 1835.  By this time he was nationally known as a storyteller, sharpshooter and hunter. Several books were published relating his tall tales.

When he lost another election to a man with a wooden leg, David Crockett set out for the Texas frontier to see if he should move his family there. At this time, he made his famous remark, “Since you have chosen to elect a man with a timber toe to succeed me, you may all go to hell and I will go to Texas.”

“You may all go to hell and I will go to Texas.”

In February of 1836, David Crockett arrived in San Antonio de Bexar. Sam Houston had ordered that his army retreat from the Alamo, but Colonel William B. Travis disregarded the order. Crockett sided with Travis, ready for a good fight. Mexican Army General Antonio Lopez de Santa Anna had arrived at San Antonio on February 20, ready to seize the Alamo.

With no reinforcements arriving, the thirteen day siege of the Alamo ended on March 6, 1836. In less than two hours, David Crockett, Jim Bowie, William B. Travis and between 185 and 255 other defenders lost their lives.   “Remember the Alamo” and “Remember Goliad” became the battle cry at the successful Battle of San Jacinto on April 21, 1836, when Sam Houston’s army defeated Santa Anna in a savage 18-minute battle.

“The Fall of the Alamo” by Robert Jenkins Onderdonk

Silver Screen Adaptations

Davy Crockett’s life has been depicted in Hollywood for decades, a topic ripe for the silver screen. There have been several movies about the famous Alamo battle in two of these, the character of Davy Crockett has been played by the likes of John Wayne and Billy Bob Thornton. In the famous 1955 Walt Disney series Davy Crockett, King of the Wild Frontier, the title character of Davy Crockett was played by Fess Parker.

Davy Crockett’s efforts to free Texas from Mexico have made him a Texas Legend admired by historians and school children alike!

Learn even more about Texas in our new exhibition, opening to the public on March 6, 2011. Get a sneak peak at the exhibition during our Texas VIP Nite, March 2 from 6 to 8 p.m. And stay tuned to the blog as we highlight other important people and events throughout the run of the show.

Rabbit in the Moon

The new moon of Thursday, February 3, was the second new moon after the winter solstice and therefore marked the Chinese New Year, beginning the Year of the Rabbit. The full moon of Friday morning, February 18, just followed the fifteenth day of the first Chinese lunar month, which is known as the Lantern Festival.

The start of this year, then, is an ideal time to look at the features on the moon and see if you can find the “moon rabbit.”  Of course, there is no rabbit in the moon, just dark splotches which some people believe look like a rabbit.  Understanding the rabbit in the moon, then, involves understanding why the moon has dark and light features.

Oceanus Procellarum is the large mare in the center and upper left of this image.
Visible in the upper right is another large mare, Imbrium, and below is the small
round Mare Humorum.

Dark and Light

The moon is not of uniform brightness because it is not of uniform elevation.  The brighter regions are called highlands because they are higher than the darker regions.  Because early lunar observers mistook these dark areas for earthly seas, they are called maria (singular mare; pronounced ‘mah-ree-a’ and ‘mah-ray’), from the Latin word for ‘sea.’   One mare which is much larger than the others has the name ‘Oceanus Procellarum,’ as an ocean is bigger than a mere sea.  Similar, smaller features bear the names lacus (‘lake’) or sinus (‘bay’).  These terms have persisted long after we realized that the Moon has no liquid water and no oceans, seas or lakes.

Lunar Prospector
Image courtesy of NASA

Ancient Basaltic Lava

Lunar mare are in fact ancient basaltic lava flows which filled basins of very large caters on the moon.  Evidence based on radiometric dating indicates that the maria formed between 3.15 and 4.2 billion years ago, with most of the lava flows occurring between 3.15 and 3.8 billion years ago.  This would mean their formation followed the Late Heavy Bombardment (4.1 to 3.8 billion years ago), when countless planetesimals collided with the inner planets of our solar system, forming many craters.  It appears that during this period, some of the larger impacts fractured the lunar regolith.  A few million years later, basaltic lava flowed into the resulting basins.

Why do all the moon’s maria face Earth?

The maria are not spread evenly across the moon’s surface, but instead are almost all on the near side of the moon, which always faces Earth.  The reason for this is a topic of active debate and research among lunar scientists.  Data from the Lunar Prospector mission indicates that under the lunar crust is a layer abnormally high in potassium (K), phosphorous (P), and rare earth elements (REE).  Further, this KREEP material is not spread evenly across the moon but is instead concentrated on the near side, specifically in the Oceanus Procellarum and Mare Imbrium basins.  As potassium and the rare earth elements uranium and thorium are heat-producing, their presence may have favored basaltic lava flows on the near side as opposed to the far side.

Naming Lunar Geography

The mare names we use today go back to Italian Jesuit astronomers Giovanni Battista Riccioli and Francesco Maria Grimaldi.  In 1651, Grimaldi prepared a map of the moon which Riccoli published in his Almagestum Novum.  Folklore associating the first quarter moon with calm weather and the last quarter moon with storms influenced Riccoli as he named the features Grimaldi had drawn.  The western limb of the moon, visible at first quarter, has seas of  Tranquility, Serenity and Fertility (Fecunditatis).  The eastern limb of the moon, visible at last quarter, has seas of Rain (Imbrium), Clouds (Nubium)  and Moisture (Humorum), as well as an Ocean of Storms (Oceanus Procellarum).  Riccoli was not the first to name features on the moon; Michael van Langren and Johannes Hevelius had used different sets of names.  However, when later lunar mapmakers, such as Johann Schröter, used Riccoli’s names, they became standard.  Incidentally, Riccoli also labeled the lunar highlands as terrae (‘lands’), but that nomenclature has not continued to this day.

Moon Legends

Many people around the world have tended to make various pictures out of the darker regions on the Moon’s surface.  The scientific term for our tendency to imagine familiar figures on the moon, or in clouds, on trees, etc., is pareidolia.  Perhaps you are familiar with the man in the moon.  His face consists of Mare Imbrium and Mare Serenitatis (eyes) along with Mare Nubium (mouth).

The Chinese, however, imagined a rabbit in the moon.  Mare Nectaris and Mare Fecunditatis form the tips of the rabbit’s ears, which come together at Mare Tranquillitatis.  Mare Serenitatis marks his head.  The large maria Oceanus Procellarum and Mare Imbrium form the bulk of his body, with Mare Vaopurm as his forelegs and Mare Nubium and Mare Humorum as his hind legs.

In an alternate image, the rabbit is facing the east (left) limb of the moon and is running instead of sitting.  In this view, the head becomes Oceanus Procellarum and the main part of the body Mare Imbrium.  The ears of the previous rabbit, mare Fecunditatis and Mare Nectaris, become the hind legs of this one.  Mare Nubium and Mare Humorun are now forelegs.  Mare Frigoris, a long ‘sea’ near the northern limb of the moon which did not figure into the previous rabbit, becomes a long ear of this one.

Photo edited by Zeimusu:
The rabbit stands by a cooking pot.
Based on the public domain moon image from
image:Luna_nearside.jpg and information on the web.

In Chinese folkore, this is the Jade Rabbit, making the elixir of life for the goddess of the moon Chang’e. In Japan and Korea, the moon rabbit makes rice cakes.  A Buddhist legend tells that the monkey, otter, jackal, and rabbit resolved to offer food to a stranger passing through the forest on the night of the full moon.  The rabbit, able to gather nothing but the grass he ate, offered his own body instead, and was rewarded by being placed in the moon.

Asian societies were not alone in imagining a rabbit in the moon.  In Aztec legend the god Tecciztecatl became the moon god after he hesitated to sacrifice himself in fire to become the sun god.  As punishment, the gods decided the moon would not be as bright as the sun. The Maya also associated a rabbit with their moon goddess.

Today, our Easter holiday is associated with bunnies.  That holiday bears a pre-Christian name which the Venerable Bede attributed to a goddess Eostre, who was associated with rabbits (among other symbols of life and fertility).  Perhaps finding the rabbit in the full moons of March and April can put you in the spirit of the Easter holiday.

In My New Skin

Yao Ming
Creative Commons License photo credit: Keith Allison
Yao Ming –
The guy just didnt stop growing.

I bet you’ve never thought of growth in as much detail as I have. As an Entomologist, I think about it a lot! It’s very simple for vertebrates. You eat, drink and sleep - and your body grows. Do you tell your body to grow? Do you try to grow? No, it just happens, slowly at times and quickly at other times. Sometimes we grow up and unfortunately, sometimes we grow out! The point is that it is an involuntary action that our body undergoes, just like breathing, blinking, salivating and blood pumping! I am so grateful to be a human and have this happen effortlessly and without many bumps along the way.  Arthropods, on the other hand, got the short end of the stick! Arthropods have to go through a serious ordeal to get from one size to another, known as molting or more scientifically, ecdysis.

Insects and other arthropods are not like us, obviously! Whereas we have an endoskeleton, or skeleton that supports our body from the inside, they have an exoskeleton, or a hard shell covering the outside of their bodies. This exoskeleton functions much in the same way as ours does. It supports the arthropod, as well as acting as a point for muscle attachment. Additionally, it protects them from certain predators and parasites and helps to keep terrestrial arthropods from desiccating or drying out. It also contains certain sensory structures that are very important to insects and their many relatives.

Exoskeletons are formed by a long chain polymer called chitin. This compound is very tough and resilient and is also found in other animal structures such as the beaks of octopi and squid. When I’m teaching kids about exoskeletons, I like to compare it to a suit of shining armor that a knight would wear. Now, if it was a young knight, he would have to grow, so he could not always wear the same suit of armor. He would have to trade it in for a new, larger one. This is the case with arthropods and their exoskeleton. In order to grow and get larger, they must shed their exoskeleton and grow a new one.

This is where things get a bit hairy! In order to shed their exoskeleton, arthropods have to go through a scientific process called ecdysis. I’ll spare you the boring scientific details, but basically, they excrete a liquid that separates their old skin from their bodies. This process is called apolysis. They then form a new skin. They excrete another chemical which digests the innermost layers of the old skin and they crawl out of what’s left. What’s left behind turns into a dry crunchy empty shell. Shortly before this process, arthropods stop eating, start swelling up a bit, and eventually stop moving or being able to function at all. If anything at all goes wrong during this process, they are finished!

katydid 012

Creative Commons License photo credit: emills1
A katydid nymph molting,
getting a little help from a friend!

Many insects have to hang upside down and let gravity help pull them out of their old exoskeletons. If they fall from their perch before they are done, they will not be able to get everything out and will either die or be severely deformed. To make matters worse, they are super defenseless during and after this process, making them prime targets for predators! If an arthropod is able to successfully complete their molt, they are stuck with this brand new, super soft exoskeleton. They can neither walk nor fly. They are completely vulnerable for at least a couple of hours. Have you ever eaten soft shell crab? Well, it’s not some cool different species of crab you’re eating, it’s just a regular crab that has been harvested right after molting. They cook it while it is still soft, so you’re eating the whole crab, shell and all. I can’t ever bring myself to eat them, it kind of grosses me out! The most commonly used crab for this, in the United States, is blue crab.

Feb2010 069

Creative Commons License photo credit: emills1
A deformed katydid due to a failed molt

If the arthropod is able to successfully remove all body parts and limbs from the old skeleton and find a safe place to rest until their new skeleton hardens, they can go on living their little bug lives, until the next time they have to molt! This process gets even more complicated in insects that have what we call complete metamorphosis, such as butterflies, beetles, flies and bees. Insects like grasshoppers, cockroaches and praying mantises go through incomplete metamorphosis, so every time they molt, they have relatively little changes in their bodies. They mainly get bigger and some grow wings. As we all know, a butterfly starts out as a caterpillar, it gets bigger as it molts, but when it’s time for it to pupate or form a chrysalis, the process of molting involves the insect changing its body completely. This makes it even MORE of a challenge for them.  It’s very interesting to note that similar chemicals that digest the insect’s old exoskeleton, digest most of the actual cells of the larva, leaving only some cells alive. These remaining cells reform the organism into a completely different looking organism, like the adult butterfly!

Feb2010 084

Creative Commons License photo credit: emills1
The Exuvia of a Giant Prickly Stick,
a walking stick from Australia.

The cast away skin of an arthropod is called the exuvia or exuvium. When it’s first removed from the animal, it’s soft, like the new skin, but as it dries out, it becomes very crunchy!

I bet almost everyone has seen one of these. You know those empty insect shells you can sometimes find stuck on trees? I grew up calling them locust shells and I used to love scaring my siblings and friends with them. Then I’d get a lot of pleasure out of crumbling them up! Well, they are not locust shells; locusts are a type of grasshopper. These exuviae belong to cicadas.

Tibicen Cicada
Creative Commons License photo credit: jasonb42882
A cicada molting.

Cicadas are those funny looking insects you hardly ever see but always hear in the summer. You can hear the rattling noise they make during the hottest hours of the day. The immature cicadas can spend anywhere from 2 to 17 years feeding on tree roots underground, depending on the species. They emerge at night, start climbing a tree, and complete their final molt to adulthood on the way up. The next day we find the shells, but the actual cicadas are high up in the tree tops by then!

Every arthropod on the planet has to go through metamorphosis that involves molting. Insects, spiders, centipedes, millipedes and crustaceans. Interestingly, millipedes are born with only a few segments and legs. Each time they molt, they add another segment and 4 more legs.  I could go on and on about the amazing molting process. The point is, next time you are getting down about anything in your life, think about how easy we have it compared to the bugs of the world. Be thankful that we have easy access to resources we need to survive, we have no real predators and we don’t have to molt! The whole process terrifies me really, so I’m very thankful!

Until next time, happy bug watching!

Your questions, answered: Do we know when chimaeras shifted to deep-water habitats?

Earlier this month we received a question on one of our past posts, The Ghost Sharks of the Jurassic, asking:

“Do we know when these chimaeras shifted to deep-water habitats? If predation and, in particular, the evolution and diversification of predatory species prompted their geographic transition, at what point would a sort of critical level have been reached to drive them into the deep? How many predators are too many?”

Why do “living fossils of the deep sea” so often represent lingering survivors of groups that long ago flourished in shallow water?

 
Rabbitfish

Examples: Rabbitfish (aka chimaeras), Coelacanths, Goblin Sharks, Giant Squid.

Excellent question – one that keeps evolutionary biologists awake at 2 a.m.

First thing: we never know when a clan of species invades deep water. This is why:

Sediments deposited on top of oceanic crust in deep-water – thousands of feet deep – rarely come to the surface where the layers can be seen by fossil-hunting paleontologists. Mud does form at the bottom of deep seas and fossils do form here. But such deep specimens have a low chance of being found by us.

Deep sea bottom mud is raised above sea level when continents collide and abyssal sediment is squeezed up and thrust across slabs of continental crust. There are narrow zones of such squeezed sediments – for example, in the Taconic Mountains of New York State. Here are slices of deep crust and sediment with deep-water trilobites. However, very few vertebrate and squid fossils are known from squeezed deposits.

Medium-deep sediment, up to 200 meters deep,  do form in the bottom of “epi-continental seas” like the famous  “Cretaceous Ocean of Kansas” that covered much of the central areas of North America. Such epi-continental seas  do drain away, and the bottom sediment becomes lifted hundreds or thousands of feet, so wind and water can erode valleys into the rock layers, exposing fossils. Epi-continental sea bottoms have given us 90% of our marine vertebrate and cephalopod fossils.

Coelacanth fossils are common in shallow-water and medium-deep sediments beginning in the Early Devonian, over 400 million years ago. From then on, coelacanths remain widespread and often common. Were they in deep water too? We don’t know – we don’t have enough deep sediment exposed for study.

Abruptly, coelacanths disappear from epi-continental sea deposits in the Late Cretaceous. Naturally, we thought they were extinct. But then the fish show up alive and well, hanging around at 130 meters to 700 meters.

Ditto for the Goblin Shark: common as a fossil along New Jersey in shallow sediment but now restricted to much deeper waters. Ditto for the giant squid, who left their shells in the Cretaceous epi-continental sea sediment but now prefer deeper water.

Goblin Shark

Is there a common explanation for all the survivors in deep waters?

The most popular theory is: 1) Most new types of fish and cephalopods first evolve in shallow water. 2) It takes time for evolution to modify a fish or cephalopod so the beast can survive at 200m + depths. So the early coelacanths couldn’t colonize the great depths for tens of millions of years. As more and more clans of fish evolved in shallow water, some began their adaptive descent too – but the coelacanth had a head start. Being fully adapted to great depth already may have protected the fish from predators and competitors who are behind in the degree of their transition.

There are holes in the theory. Coelacanths do have predators – they show up in shark stomachs. They must have competitors too – teleost fish with more complex jaws.

Deep Sea Refuges continue to irritate our neat little hypotheses.

WAnt more? See the past post on ghost sharks and full comment.