August 21, 2011
QUEEN CONCH COME-OUT
Up at the rocky point you see lots of empty, bleached-white Queen Conch shells (conch pronounced KONK), not least because the locals eat them with relish, year round. When I saw a smallish conch shell moving across the sand close to shore in less than a foot of water, it was usual.
It was also strange that through the choppy water I seemed to be seeing three or four black, slender, straight appendages below the shell. Was this an aquatic hermit crab carrying a borrowed shell around? When I retrieved the shell from the water, at first the creature cowered so far inside that only a hard, claw-like structure and some soft, brown flesh showed. But then the claw extended farther, and a pair of stalked eyeballs emerged staring at me, as shown at http://www.backyardnature.net/n/11/110821qu.jpg.
For several seconds I stood there trying to reconcile the thought that we had a hermit crab with one claw extended, but the knowledge that crabs are arthropods with jointed legs and brittle exoskeletons. Yet the leg attached to the claw right in front of me looked like a mushy mass of exposed flesh. The flesh looked like that of a snail or other mollusk, but do mollusks ever have claws? Maybe the black, strawlike things I'd seen had been antennae and stalked eyes, not legs.
The critter and I gawked at one another mutually clueless as to what we were seeing when suddenly for half a second it was like that scene in the 1979 movie Alien when a slimy space monster bursts from the chest of an astronaut. Something like an impossibly long -- for such a small shell -- fleshy arm hooked at the end and bearing stalked eyes where the elbow should be shot from the shell right at my face, then collapsed from its own weight and began hacking at my arm with its hook. You can see the eyed, hooked arm at http://www.backyardnature.net/n/11/110821qv.jpg.
After a few seconds the creature seemed to realize how exposed he was and how useless it was hacking at my arm, so he withdrew more into the shell, his roving stalked eyes looking around, as shown at http://www.backyardnature.net/n/11/110821qw.jpg.
The short version of the rest of the story is that soon a bit of Googling convinced me that we were simply being granted an unusual view of the Queen Conch living organism. Marcia says she's never seen a conch behave like this, and on the Internet among hundreds of pictures of living Queen Conches, none that I find show the body so extended from the shell, ending in a hook.
That hook is actually an operculum, the stiff covering many snails and other mollusks bear at the bottom of their feet. When the mollusk withdraws into its shell, the fingernail-like operculum is the "door" closed against the outside world. I find no reference to Queen Conches using their operculums as hooks in self defense, which is just as well, since it looks more dangerous than it really is.
In that last picture, of the face, it's easy to recognize the stalked eyes, but what is that fleshy, fingerlike growth arising immediately below and between the eye stalks? That's the proboscis, or snout. Notice how the proboscis bears a slit at its end. That's the mouth. The large, fleshy area below the eyes and proboscis constitutes the foot, and we've seen that that foot can be extended much farther than in the last picture.
It seems that I'm learning about these things just like a kid does, poking about on my own and sometimes having the bejeezers scared out of me, and that's exactly how I like it.
Despite the year-round poaching of conch by local folks along the beach, laws are in place to protect the Queen Conch. Here it is illegal to capture, buy, transport, sell or even eat conch from May 1 to October 31. Queen Conches are mating now, and that's why this week I got to see one so close to shore.
In the interior we've seen heavy, year-round poaching of deer and other wildlife, despite adequate laws being on the books. Here maybe the conch laws are taken a little more seriously and I think I know why: To the military who constantly patrol these waters, conch hunters at a distance look just like drug runners.
Still, since I've been here I've heard of three local conch-busts by the military. Last week a local man gathering conch along the beach near his house in Sian Ka'an Biosphere Reserve was arrested. The other two encounters were late at night when a military patrol boat stopped poachers offshore in boats. Guns were fired in both instances, and one poacher -- who had been caught and released during the previous encounter -- was shot in the leg as he tried to escape.
During the last encounter, the poachers dumped about 500 pounds (225kg) of conch overboard to get rid of evidence.
MOSTLY WHITE YUCATAN JAYS
Each morning I bike through a raucous, hyperactive flock of Yucatan Jays. You can see some of them in a Hurricane-Dean-killed tree at http://www.backyardnature.net/n/11/110821yj.jpg.
Though Yucatan Jays occur only in the Yucatan Peninsula, northern Belize and Guatemala, the species is common here. What's special about the above picture is that juveniles are present with their yellow beaks and mostly white plumages. Adult Yucatan Jays are completely black and blue, except for their yellow legs. Immature but past-juvenile birds look like the adults, but have yellow beaks and narrow, yellow rings around each their eyes. The eye ring doesn't become black until the third winter. The picture shows, then, three immatures, a juvenile "yearling," and an adult.
It's not surprising to find such a range of ages in a flock of Yucatan Jays. They are profoundly social birds and their flock structures are unusually complex and variable. Sometimes you see one adult bird feeding another, and sometimes food is passed back and forth among several birds before being eaten. In the wild you don't see Yucatan Jays fighting. They're "cooperative breeders," which means that several birds may be involved with a nest, and the helpers may exhibit various ages and sexual status.
All this information and much more is documented in a wonderful paper by RJ Raitt, called "Behavioral Ecology of the Yucatan Jay," which appeared in the December, 1976 edition of The Wilson Bulletin, and which now is freely downloadable in PDF format at http://elibrary.unm.edu/sora/Wilson/v088n04/p0529-p0554.pdf.
ARBOREAL TERMITE NEST, AND OUR HAWK
Arboreal termite nests are conspicuous features of the landscape here. You can see a typical one in a hurricane-killed Poisonwood tree, with the immature Common Black Hawk we've been watching for months atop, at http://www.backyardnature.net/n/11/110821tn.jpg.
Such nests, which I'm guessing belong to the termite genus NASUTITERMES, are common in most of the Yucatán, though they become scarcer or disappear toward the arid northwest.
It's interesting that they were very common at Sabacché south of Mérida. At Hacienda Chichen it was hard to find a nest, though many big Piich trees had the termites' mud tunnels running up their trunks. Up there the Maya told me that parrots and parakeets nest in and destroy the nests, which sounds plausible, since parrots and parakeets are more protected in the ruin area and seem to be much more common than at Sabacché where they were hunted for the pet trade.
Here we have an opposite situation to that at Hacienda Chichen. Here plenty of nests are to be seen but so far I've found no mud tunnels leading from the ground up to the nests. Here we also have parrots and parakeets, but not as many as at Hacienda Chichen.
Someday figuring all this out will be a good project for a graduate student.
AUSTRALIAN PINES DROPPING SEEDS
Maybe you remember that during my 2008 visit here we made a Christmas tree of one of many Australian Pines growing on this low sand ridge. Australian Pines are aggressive alien species that shoulder aside the native flora, so we didn't feel too bad about sacrificing one. Australian Pines aren't really pines, but they look like it -- much like the Loblolly Pines back in Mississippi. You can see what they looked like beside the hurricane-ravaged mangroves in 2008 at http://www.backyardnature.net/yucatan/casuarin.htm.
The trees in that picture, about six feet tall, now are about 20 feet tall. Though Marcia says that before Hurricane Dean Australian Pines were rare or absent here, in places now they form dense, pure stands. Nowadays their cones are releasing seeds onto the ground. You can see a cluster of cherry-sized cones at http://www.backyardnature.net/n/11/110821cs.jpg.
A cone with three papery-winged seeds below it is at http://www.backyardnature.net/n/11/110821ct.jpg.
Though Australian Pines aren't pines -- aren't members of the genus Pinus, but rather Casuarina -- it's proper to call Australian Pine fruits "cones." They're cones because they are, along with pines, gymnosperms. Still, Australian Pine cones differ from cones of real pines in that their seeds do not fall from beneath woody, overlapping scales, but rather from what look like little turtle heads that spit out the seeds. You can compare our Australian Pine cone with a big, fragrant "real" cone of Jeffrey Pine in Oregon at http://www.backyardnature.net/n/09/090426jq.jpg.
Every day seaweed of various kinds floats up on the beach, giving our garden crew an unending job to keep the swimming beach clean. You can see what a typical, free-floating bunch of what's been coming in this week looks like as it approaches the beach before stranding at http://www.backyardnature.net/n/11/110821sg.jpg.
You can see it accumulating on an a wild beach at http://www.backyardnature.net/n/11/110821sh.jpg.
A close-up showing this seaweed's golden color, pea-sized air bladders, and leaves with toothed margins is at http://www.backyardnature.net/n/11/110821si.jpg.
The color, the bladders and toothed leaves all distinguish this as the brown alga known as Sargasso, genus Sargassum. Numerous Sargasso species are distributed throughout the world's temperate and tropical oceans, but in this part of the world the two main freely floating ones are Sargassum natans and S. fluitans. I read that the bladders of S. natans each bear a needle-like spine, which is lacking on S. fluitans. Since our bladders bear no spines, I'm guessing that what's floating onto our beaches is Sargassum fluitans.
Sargasso is famous because of the Sargasso Sea, a vast pool in the central North Atlantic choked with floating forests of Sargasso, which harbor incredibly diverse concentrations of living floating organisms.
When you see the sheer quantity of Sargasso biomass that washes ashore, dries out, and eventually merges with the mineral beach, it's easy to believe that what accumulates must be important to beach ecology. You can see how fresh Sargasso next to the water first is golden, then darkens with age, and finally shrivels as it dries out, and vanishes into the sand at http://www.backyardnature.net/n/11/110821sj.jpg.
On the Internet I find an occasional mention of Sargasso being used as mulch. We do that, too, mixing it with wet kitchen scraps once rain has washed off some of the salt. Wet kitchen scraps tend to clump and missily rot without the Sargasso's bulk mixed in. The Sargasso enables air to circulate better and, like a sponge, holds moisture needed for the decomposition process.
Also a study shows that goats fed Sargasso gained weight as fast as if the were eating a regular goat diet, so it seems to me that Sargasso is nutritive. Though I find no studies on the matter, I suspect that "Sargasso drifting ashore" is an example of nutrient and energy transfer from the open sea to the beach ecosystem. Solar energy captured in open water ends up fueling springtails on the beach, and sandpipers who eat the springtails.
ADENIUM, NOT A ROSE
Marcia definitely has gathered some interesting plants at Mayan Beach Garden. When I arrived a potted one caught my eye because its gray, succulent stem bulging into at the base looked like a stem of the Mexican Poneytail (genus Beaucarnea) often seen in the Yucatan, but its leaves were completely different. I've been awaiting that plant's flowers so I could identify it, and now this has happened. You can see the plant at http://www.backyardnature.net/n/11/110821ad.jpg.
A glance at the flowers told me what family the plant belonged to, for the large, trumpet-shaped corollas with their five flaring lobes are very similar structurally to Yellow Oleander, Oleander, Frangipani, Mandevilla, Mangrove Vine and others we've seen lately -- all members of the Dogbane Family, the Apocynaceae. Remembering that those flowers all have five anthers clustered at their mouths, I opened a flower plucked from our potted mystery plant and saw what's shown at http://www.backyardnature.net/n/11/110821ae.jpg.
In the picture's lower, left corner, the slender, fuzzy, brownish items directed upward are anthers clustered at the flower's mouth. However, there's also this: Each anther is topped with a stiff, pink-toothpick-like appendage. Those appendages help define the genus of our mystery Dogbane-Family plant. What we have here is one of the many horticultural cultivars of ADENIUM OBESUM, the "obesum" referring to the fat, bottom-bulging, succulent stem.
Well, this is excellent. Adenium is known as a genus of spectacular succulents from tropical Africa and Arabia, some of them making small trees with swollen trunks and standing up to 15 feet tall. And, as one website declares, "Despite their beauty and ease of culture, adeniums are not nearly as popular as one might expect. Perhaps they simply haven't received the exposure they deserve."
Among the neat facts about Adenium obesum is that it, along with a couple other species, contains toxic cardiac glycosides, used as arrow poison throughout Africa for hunting large game. The species is also much used in bonsai.
In the English-speaking world the main common name for Adenium obesum is Desert Rose, which is disgraceful. You can see that the plant is nothing like a rose, plus there's much more to it than that it grows in the desert. Such wonderful species deserve better. In fact, many nurseries now just call it Adenium.
You can get a good orientation on the genus Adenium at http://adenium.tucsoncactus.org/.
Monday morning the "Tropical Weather & Hurricanes" page at http://www.wunderground.com/tropical/ showed an area of "disturbed weather" off the coast of Guyana, northern South America. Not strong enough to be called a tropical depression, meteorologists labeled it 93L. Computer models projected that during the coming week it would wander westward across the Caribbean, strengthening until coming ashore in this general area.
These kinds of weather systems spook property owners along the coast here, such as my hosts at Mayan Beach Garden. They know that one big hurricane hitting us just right could put an end to our pleasant little world.
Therefore I felt guilty about hoping we'd see at least some of 93L's storminess. I couldn't help it. I love storms, though of course I'd never want my friends to suffer again what they did with Hurricane Dean in 2007, or worse.
I wonder: Is there something in human nature that somehow hankers for occasional crises, unexpected emergencies, and temporary chaos, such as storms can afford? I wouldn't be surprised if it's so, since humanity evolved in such a crisis-rich, dangerous, sensory-overloading world that surely our genetic programming takes account of it.
In fact, maybe humanity actually needs occasional crises if society is to work properly. Sporadic small crises help answer the question, "If a disaster arises, who'll freak out, and who'll be heroic?" Tame, orderly worlds don't answer that question, even though it's an important one.
That might explain why Nature might predispose a certain percentage of us to enjoy having things shaken up a little when life is going too smoothly. And that doesn't even take into account the esthetics of a good storm, its riotous juxtapositions of color, sound, odor, and tactile sensations. A good storm is symphonic, poetic, instructional and, to some of us, nurturing.
Whatever the reasons, this week as 93L wandered our way, growing into "Tropical Depression Eight" Thursday night, then Tropical Storm Harvey on Friday, I found my heart quickening, my mind focusing, and I began spending more and more time on the beach gazing stormward, glowing with an interior smile.
Best wishes to all Newsletter readers,