Archive for the ‘Biology’ Category

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Who’s an invertebrate?

February 17, 2015

An invertebrate is somebody with no backbone.

Wait, who you callin’ spineless? I’m happy as a clam!

Yes, for example, a clam is an invertebrate. As are many other squishy aquatic creatures, like  the 30 foot long ocean worms! Yikes! So are octopods and squids. The mighty Kraken!

Insects are also invertebrates, as are spiders, and those wild scorpion creatures!

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You might notice a pattern here—many invertebrates, especially aquatic ones, like the magnificent octopus and kin, may have no hard structure at all.

Others often have external support systems, like shells in mollusks, or the exoskeletons surrounding insects and Transformers. Especially desert creatures, who like a bit more protection from the elements.

And by the way, when you think of spineless jokes? Just remember, it’s probably good form to be polite. Especially about invertebrates. Remember, there are way way more kinds of them than there are of us bony beasts. And way way way more individuals!

And some of them bite or sting! No way!

And some of them look so amazing they will knock your socks off!

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Too Wet!

January 9, 2015

A surprising limiting factor in some parts of the desert is too much moisture.

Wait, you say, I thought deserts were too dry?

Because there’s usually so little rain, nobody is really prepared for much. So even what might be considered a light rain elsewhere can be enough to flood out desert burrows, nests, hollows, and lowlands. If you are a creature who can move fast, or a plant that can hold its breath, you will get through it.

But even in the desert, rain is not always light. During the summer monsoon months, and a few other times of year, there can be heavy downpours.

And adding to the effect, there’s that old caliche we talked about before. This is the impervious layer of minerals and clay that forms over time a short distance down under the desert surface, and acts as a water-trap. The water can’t sink in–so where it can, it slides off downhill.

With a light rain, you can suddenly get a flash flood. With a heavy, or extended rain, you can get massive dangerous flooding, the kind that kills animals, large as well as small, and washes away trees and cars and buildings.

In the middle of many human habitations in the desert, you will find long empty wild spaces, often called “washes.” These are where the flash floods wash through, carrying away whatever is in their path.

It’s strange, when you think about it, how moisture could be a problem, and a limiting factor, in both directions in the desert.

Or maybe not. Because a lot of living things want conditions that are not too much, or too little. Instead, they want things to be generally within an agreeable range. So when you look at a limiting factor, it can be fun to check if there is another one lurking at the opposite side. Yet another mystery.

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Who lives in this cactus?

December 1, 2014

Who you find living in any particular cactus will depend on when you look.

Many of the large holes in saguaros are originally drilled (although the process sounds more like a jack hammer than a drill) by Gila woodpeckers, who peck into the cactus to hollow out an area for a nest.

One interesting result is that the cactus, always fearful of losing moisture, forms dense scar tissue around the excavated area. This means that when the cactus dies and the flesh falls away, what’s left is the interesting lattice of cactus skeleton, plus an occasional hard rounded shape that looks something like a boot—so it is called a cactus boot. Native people gathered them and used them as containers for liquids.

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Back to the cactus-dwellers. While the plant is still alive, these nests drilled inside saguaro cacti are prime real estate, the perfect place to find thorn-protected shelter until the kids grow up and fly away. At first, after the cactus heals and get less gooey, the  Gila Woodpeckers or related birds who excavated the nest holes get first dibs. But later years may bring entirely new sets of residents.

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Zoo or Noooo?

September 26, 2014

How can you tell if the prairie dog in the picture has been living in the wild or a zoo?

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Check out how pudgy the creature is.

Zoo animals often gain a lot of weight—from eating so many carrots!

On the other hand, or paw, wild prairie dogs stay lean by going to the gym several times a week.

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New Desert Creatures Mysteries e-book

August 12, 2014

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Now you can get a great Desert Creatures Mysteries e-book.

It goes into detail about the strange animals of the desert, and some of the cool science about them.

https://www.smashwords.com/books/view/455225

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What’s the buzz?

July 2, 2014

At the end of June you may hear a new sound in the trees–a long loud buzz, much too long and loud to be coming from a hummingbird.

It most likely is a cicada, an large insect that makes this quintessential summer sound with specialized organs on the sides of its body.

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If you keep an eye out, you may find a very ornate discarded cicada shell, since they go through different versions as they grow, and no longer fit in their old shells.

Cicadas are found all over the world. The one pictured is from northern North America.

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Leafing so soon?

May 2, 2014

There are leaves and then there are leaves. And then there are cactus pads, like this wide flat prickly pear cactus pad, which are more like stems than leaves.

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Because if you look closely, on the surface of this pad, you will see the actual leaves, small succulent pointy cones, next to their associated thorns, which form in the axil (that’s like the armpit!) of the leaves.

The thorns persist, as most desert dwellers know too well, but the little leaves fall off in a matter of days, another water-saving feature, so only the thorns and the thick-skinned pads, and the quickly hardening new pads, remain.

Stems or not, the pads, after the skin and thorns are very carefully removed, have been used for centuries as food by native civilizations in the desert

 

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Packrat Middens

November 3, 2013

Packrats, Neotoma albigula, make interesting nests in which to store their treasures—and themselves.

When you are out in the desert, the trick is how to spot a packrat nest. It’s not always easy. I guess that’s the idea, when you are building a hideaway.  Basically, look for a crazy, almost random pile of sticks and leaves, and often cholla cactus stems. The nests can range from a foot to 8 feet wide, and are often at the base of a shrub or cactus.

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Apparently, If you went inside a packrat nest or midden, an activity the packrats vigorously discourage, you might find shiny bits of human treasures—foil, metal, or other bright objects, since packrats seem to like shiny things as much as we do.

Packrats do like cholla cacti, somehow managing to avoid their really nasty and determined thorns. There’s even one variety called the jumping cholla—I would stay away from those! The name comes from how easily a stem can get detached and glom onto you. A packrat favorite! Cholla stems are certainly a good defensive addition to a habitation—the dry stems are probably even nastier than green ones. According to the Desert Museum, packrats love to eat prickly pear fruit. So they are really cactus creatures.

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Limiting Factors—Cold!

February 4, 2013

If you were in the Sonoran desert in January 2013, you may well have experienced a limiting factor that many people would not expect in a desert: freezing damaging cold.

In many places it dropped into the 20’s or lower at night, for several nights, enough to nip many buds in the bud.

Native plants, which have been through this before, generally survived quite well, but imports, or annual vegetables, either got crisped or completely melted down.

This suggests that planting native species has even more benefits than we usually consider.

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Herds of Callipepla gambelii

November 20, 2012

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For a long time through the summer, when you saw Gambel’s Quail, Callipepla gambelii, in the Sonoran desert, you’d usually see just one or two individuals.

Then in late summer, there were groups of 4 or 5.

As the weather cooled (well, cooled relatively speaking—this is a southern desert) and autumn officially started, suddenly there are huge herds of up to 20 quail. Yes, I know, covey, more accurately, coveys of quail.

In the new year, they will pair off, the big groups will disperse, then new family herds of mom, dad, and sometimes more than a dozen little peepers, who are amazingly fast soon after hatching, will appear on the scene.