Thursday, September 29, 2011

Maybe She Will...Maybe She Won't

A big female crab spider about the size of a small quarter dollar.

Crab spiders or, more precisely, misusenoides formosipes, are found on flowers where they wait to ambush typical pollinators.
Popular thought says the spiders change color to match the flower they're on.  Fun!  This one was found  in a neighbors yard and the color match was so precise the camera had to define where the flower started and the spider ended.  
White crab spiders will sit in white Datura blossoms...yellow ones hide in...well...yellow blossoms.  
Two theories exist.  One is that when these spiders travel to a new location, a different flower of a different color, the spider's color will change in about a week.  The other theory postulates that they simply assume the color of the flower they were hatched on.
The result is probably academic...a female that changes color is fairly common.
Crab spiders make use of camouflage more than other spiders.  The color of the spider is adapted to the hunting terrain.
Because they sit in easily spotted places they become vulnerable prey.  When they spot a possible enemy they move quickly to the other side of their location or leave. 
Crab spiders are recognizable if you tease them. They spread their legs and move side a crab. 
Although crab spiders are fairly common, finding one might take some patience because they are often well camouflaged. If you want to find a crab/flower spider, try to think like a spider: Where would you sit if you wanted your prey to come to you?

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Monday, September 12, 2011

Beauty to Tatters

Datura is a genus of nine species of vespertine (evening) flowering plants belonging to the Solanaceae family.  Its natural distribution is uncertain.
Pristine at first (above), the blossom's appearance belies its poisonous content.
Our Datura is a "witches' weed," along with deadly nightshade, henbane, and mandrake. Most parts of the plant contains toxic hallucinogens and datura has a long history of causing delirious states and death. 
It is known as an essential ingredient of love potions and witches' brews in literature.  Recall Shakespeares  witches scene...but into this exotic mix comes a common katydid (below).  Ubiquitous throughout Arizona, the critter wants a meal, not a lot of words or to have its picture taken.
All Datura contain tropane alkaloids such as scopolamine, hyoscyamine, and atropine in their seeds and flowers and has been used in some cultures as a poison and hallucinogen. Delirium and hallucination are different but for particulars you'll have to ask the katydid.  
There can be a 5:1 toxin variation across plants and a given plant's toxicity depends on its age, where it is growing, and the local weather conditions. This variation makes Datura especially hazardous as a drug. In traditional cultures, a great deal of knowledge of Datura was critical to minimize harm. 
But what of the katydid?  
It cares little for toxicological  descriptions but instead feeds on the blossom until the late morning sun begins to close the bloom and it's time to move on.  Stoned, sick or happy its had breakfast but the datura is reduced to tatters.

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