February 18, 2006
During low tides when I'm wandering around Hotel Reef I see lots of barnacles. They're stuck to any rock that's flooded at high tide, to older mangrove roots and pneumatophores -- even to plastic bottles and other trash that's been floating for some time. During my weekly walks I cross a shallow stream by stepping on cinderblocks someone has placed there. The blocks are submerged only briefly at the very peak of high tides, but even they are completely encrusted with barnacles. This week I picked up a barnacle-covered seashell, brought it home in a jug of saltwater, and you can see it in my hand at http://www.backyardnature.net/yucatan/barnacle.jpg .
That picture shows that a barnacle consists of a low, stony, crater-like structure inside which resides something like a clam composed of two shells standing on end, opening upward through the crater's hole. In the picture, some craters are empty but in others the closed, clam-like shells are clearly visible. The stony crater sides slant over the clam-like shells enough to imprison them. The question then arises, how does a barnacle make its living stuck in such a prison?
When the tide comes in the clam-like shells inside the crater open and the organism's modified legs, called "feeding legs," or cirri, extend outside the shell, and direct food particles such as algae suspended in the water into the organism's mouth. You can see a diagrammatic cross-section of all this at http://www.mesa.edu.au/friends/seashores/barnacles.html.
I placed the barnacle-encrusted seashell into a bowl of saltwater brought from the lagoon and waited for the clam-like shells to open and the animal inside to go to work. For the first couple of days I saw nothing, but then one morning there they were. The upended, clam-like shells were open and the feeding legs were being rapidly flicked into the water and then just as quickly withdrawn into the shells at a rate ranging from one to two flicks per second. The two shells inside the craters stayed cracked open all the time but they opened wider when the legs were flipped outside. From above, each barnacle's shells looked like two thick lips surrounded by a stony beard, with a furry tongue darting in and out. From the side, the legs' movement was just like you might make with your cupped hand if you were trying to coax wispy incense toward your nose. The barnacle-creature was coaxing algae-rich water into its shell-guarded mouth.
Now I understood how a barnacle cemented to a rock fed itself, but not how it attends to the matter of sex. Barnacles are arthropods, along with insects, spiders and lobsters, so I guessed that barnacle procreation was more complex than simply releasing sperm into the water on the theory that a female might be in the vicinity.
On the Web I read that Mother Nature has come up with a neat solution to the problem. She has equipped barnacles with what may be -- proportional to the barnacle's size -- the biggest penis in the animal kingdom. The barnacle simply cracks his clam-like shell a bit, sticks out his penis and probes the neighborhood for receptive female organs. Here anthropomorphism leads only to feelings of inadequacy. Anyway, after fertilization the eggs are brooded until they hatch as microscopic larvae -- as many as 10,000 in a brood. The larvae then float in the sea until they've grown enough to settle down, attach themselves to firm surfaces and start secreting the crater-like structures seen on my seashell.
Lots of barnacle species exist, but they fall into two main groups -- acorn barnacles and goose barnacles. The crater-like ones on my seashell are acorn barnacles. Goose barnacle shells reside atop large, fleshy stalks. Drawings of the two types are shown at http://www.museum.vic.gov.au/crust/barnbiol.html.
AWAKENING TO FIDDLER CRABS
Many times in my life I've made memorable nature observations thanks to my hypoglycemia. It works like this:
I'm out wandering, my blood sugar drops very low and I get profoundly sleepy. I lie down and when I awaken my prolonged quietness has caused animals in the area to forget my presence. As I lie there unmoving I can watch animals behaving as if I weren't there.
This happened to me the other day. At Hotel Reef I'd just enjoyed my weekly breakfast of beans and tortillas. Maybe I'd eaten too much because when soon thereafter I was wandering among the mangroves and my breakfast carbohydrates began breaking down into glucose, my pancreas started overproducing insulin, my blood sugar dropped drastically, and I just had to take a nap. Next to the new, post-hurricane causeway across a lagoon a big limestone rock had tumbled amidst some mangroves so I just lay down on the rock and went to sleep.
When I awakened I found myself gazing into a tangled jungle of living and shattered mangrove stems, sprawling aerial roots and vertically rising pencil- like pneumatophores. The tide was low so the floor of the tangle was coated with a greenish-gray slime of mud and algae left by the receding water.
Stationed three to five inches apart across the slimy jungle floor were little fiddler crabs about the size of the last joint of my small finger, and they were all signaling in fiddler-crab semaphore.
They were squat, dark creatures, each bearing a single oversized, pale to almost white claw. The signaling consisted of a quick movement of the pale claw rather like the chopping action of a karate expert breaking a brick on a table before him. Each crab's choppings were separated by about five seconds. These were males defending their slimy territories by flaunting their big claws.
My first reaction was how ridiculous it all as, those dozens of creatures expending such energy waving their big claws about. However, as I studied the situation I began seeing that there was some sense to it.
For, if you watched long enough, you could see that each crab had his own chopping technique. Some chops were fast, crisp and evenly spaced while others were half-hearted and/or erratically spaced. Some choppers seemed to lose their train of thought and their chipping trailed off, while others chopped obsessively. Some crabs chopped from the center of large patches of algae-rich slime, which they fed on while they chopped, but others chopped from corner plots hemmed in by roots and stems where the mud showed little green cast, and therefore contained little algae for eating.
In fact, it looked like the best choppers usually occupied the largest and/or greenest plots. The feeblest choppers usually occupied the least-green spots or spots more exposed above to attack by birds and other predators. I would not give crabs credit for being able to rationally deduce the meanings of symbolic gestures, but I do believe that over time evolution can encode in crab genes the message understood by all crabs that "If this individual can deliver such a fine karate chop with his big claw, just consider what might happen if real combat over this slimy plot should take place... "
Gradually my blood sugar level rose, my brain awakened, and things around me began making sense. How beautiful was that slimy world in which dozens of flashing, symbolic karate-chops diverted big claws from being used in ignorant combat.
AMAPOLA FLOWERS, ORIOLES & BEES
At the back of the hacienda there's a 15-ft-tall tree somewhat homely with its stubby, stiff branches and dry-season leaflessness. The tree's smooth, gray bark reminds you of saggy elephant hide. There's little symmetry about the tree. Mostly the tree is just a tangle of blunt stems leading off in every direction and set atop a fat, gray trunk.
However, as with everything in nature I have ever seen, no matter how plain it looks most of the time, always there's a certain perspective one can take, or a perfect time for visiting, during which the thing shines with such beauty that one just has to stand and admire.
The ugly tree's time is now, for it is flowering, and those flowers are something to see. Set at the end of thick, leafless branches and looking like bright shaving-brushes on long, gnarly handles, the flowers are about six inches long. The flowers' shaving-brush- like "bristles" consist of about 400 pollen-producing stamens and one stigma-bearing style, all slender, stiff and white. You can see a blossom at http://www.backyardnature.net/yucatan/bombax.jpg.
I have no English name for the tree, for this is a tropical American species seldom planted elsewhere and usually it is uncommon even in its distribution from Mexico to Nicaragua. In Maya it's called Amapolo. In the Nahuatl spoken by the ancient Aztecs and still used in much of central Mexico it's Xiloxóchitl, which means "Cornsilk Flower." Sometimes in Spanish it's called Cabellos de Ángel, which means "Angel Hair." Both these last names refer to the blossom's abundant long stamens. The tree's Latin name is BOMBAX ELLIPTICUM, and it's a member of the tropical Bombax Family, so it's related to the kapok producing Ceiba I told you about a while back.
Visiting the tree not long after dawn as the day's first sunlight slanted in from the east, the Amapola's unopened flowers looked like long, slender, brown, cigars. The brownness was contributed by the flowers' long, slender petals, which were brown on the outside and slightly connected to one another along their margins. Instead of the petals separating from another from their tips, first they would buckle outward at their bases and slits would appear between the petals around the base of the "brown cigar."
Thus as I arrived two overwintering Hooded Orioles, gorgeously orange and black against the dark blue sky, were busily flitting from opening flowering to opening flower sticking their bills into the vertical slits at the flowers' bases, sipping nectar.
And those birds must have been rewarded with copious nectar, for I could see how vigorously their throat muscles worked as their bills poked through the slits. I also saw how glistening beads of nectar clung to the birds' withdrawn beaks, and how the birds themselves peed as frequently as sapsuckers at sap-rising time up North.
As time passed the flower petals split from one another irregularly, with some remaining joined to their adjacent petals and others coming undone completely, but eventually every flower had its tuft of stamens and style completely unsheathed. In the picture you can see that the two petals nearest the camera are still united, except for the slit between their bases.
The open blossoms attracted not only Hooded Orioles but also honeybees, but the bees seemed to be mostly or entirely interested not in the nectar at the base of the many long stamens but in the pollen at the tips of the stamens. It was nothing to see an oriole probing deeply into the stamen tuft while six to ten bees worked the same flower's stamen tips.
All these sweet, lush bouquets in a brown, dry-season- parched landscape attracted beetles, flies, gnats and more. Sometimes the orioles would catch an insect and gobble it down while hardly missing a beat rushing from opening flower to flower. Nor were orioles the only birds. A Least Flycatcher was kept busy and I could hear his tiny beak snapping sharply upon insects too small to show through my binoculars. Even an uncommon, endemic Yucatan Woodpecker passed through, though he seemed more interested in peripherally participating in the communal commotion than in accepting anything the Amapola directly offered.
In an old botany book found moldering in the hacienda's library I read that in the Mexican state of Veracruz a tea of Amapola flowers is used against fevers and coughs. A decoction of the tree's bark and root is used for toothache and strengthening the gums. The flowers are often gathered for decorations in churches, and some Mexicans say it is as pretty as any flower they know.
BROWN, DRY-SEASON SCRUB
Above I mention our "brown, dry-season-parched landscape." To grasp how delightful it is to find something as lush and delicate as the Amapola's flowers in our surrounding scrub forest you really must have some idea of how dry, scratchy and generally harsh the scrub is right now.
It happens that this week Vladimir took a picture of me next to a native cactus in the scrub just outside the hacienda's grounds. I'd planned to tell you about the cactus, for we're supposed to have 12 species in the northern Yucatan, of which ten are endemic -- found only here in the whole world. However, as so often is the case, since there are no fieldguides or other accessible, comprehensive guides to the flora, I can't identify it, and can't tell you much about it.
However, Vladimir's picture shows the brown scrub behind the cactus and me, with most of the trees and shrubs leafless because of the dry season. It's at http://www.backyardnature.net/n/06/060218.jpg.
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BLUE-EYED DOG THOUGHTS
We still have the Siberian Husky with blue-gray eyes who wandered in starved and injured two weeks ago. He's gaining weight and Katharine had the local vet give him some vitamin shots. She's also placed a "Give This Dog a Home" poster at the English Library in Mérida, bearing the portrait of him you can see at http://www.backyardnature.net/n/06/060218x.jpg.
Every time I see him -- which is many times each day since he camps right outside my door -- my mind starts grinding on this question: What it is in the human character that lets a dog like this, and people as well, get into such a bad shape?
Here is the main insight crystallizing around the matter: Of all the Earth's animals we humans have been granted the greatest powers of empathy. No other creature can weep just from hearing a sad story, or from seeing the misfortune of a creature belonging to another species. As far as I am concerned, humanity's highly developed sense of compassion for living and otherwise beautiful things is its most admirable attribute.
Yet, compassion can be debilitating and destructive. If we loved all animals as much as we care about ourselves, we'd never walk in the grass -- or move about anywhere for that matter -- for fear of killing insects. Yet, if we don't move about, our bodies would get out of shape, and so many of our potentials as humans would be wasted.
To live enriched lives as enlightened animals on Earth, we must choose a Middle Path between absolute empathy for all life, and absolute insensitivity.
My experience with the Blue-eyed dog and with my own culture convince me that most of us by no means follow the Middle Path between absolute empathy and absolute insensitivity
For, not many of the gratifications of living in a consumption-focused society become available because of one's sensitivity. Only by being insensitive to the life of the cow can one enjoy a hamburger. Only by not thinking about the destruction of streams, land and organisms living there, can one turn way up the thermostat, knowing that much of the energy used comes from the burning of strip-mined coal. Only by not thinking of the suffering of families in Iraq can one swallow the sad mixture of patriotic and fear- mongering rhetoric used to rationalize why our military occupies that country.
The blue-eyed dog tells me that the Universal Creative Force has created humans with the capacity to FEEL, as no other creature on Earth can. Yet, in the Force's wisdom, also we have been granted the ability to turn off our feelings when it's necessary.
The sad part is that at this point in human evolution we are turning off our feelings not just so we can fulfill our potentials, but also so we can have our hamburgers, wear light clothing inside during the winter, and feel good about exercising military might on innocent people.
The blue-eyed dog lies beside my door having nightmares, and maybe I can guess what his nightmares are about.
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