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Wild Turkey (Meleagris gallopavo)

My posts about animals are based on personal favorites but I have also tried to choose categories of animals in a manner which reveals something larger about zoology and taxonomy.  You have probably noticed that my featured creatures are not arbitrary but are arranged taxonomically according to Linnaean hierarchy in the manner which follows:

I have not written about a family yet because I was leaving myself some room for the future (feel free to make suggestions).  Additionally, I have only written glancingly of kingdoms or domains because those overarching categories are far too large and baffling for me to deal with meaningfully (although I would probably choose the domain “bacteria” if I had limitless time, resources and a great deal more knowledge and intelligence).  The missing bottom category of species is always applicable to whatever the featured species of the day is (or, in a pinch, to Homo sapiens, the dark meddlesome, magnificent species behind history, art, politics and other non-animal, non-plant topics over there in the category cloud).

Not only have I have chased the representative members of my chosen taxonomic categories through art, mythology, and anecdote, I have also tried to write as cogently as I am able about their behavior, biology, and morphology (biologists and morphologists are no doubt laughing into their hands right now, but, hey, you guys are not always the most compelling or comprehensible writers, so give me a break). Also, I understand that traditional hierarchy is coming to be re-assessed in light of new genetic evidence and the innovative ideas of cladistics: maybe my categories were already hidebound to start.

Western Coral Snake (Micruroides euryxanthus) photo by David M. Dennis

I mention all of this because I am beginning to feel pinched by some of my categories.  I could write about a different obscure catfish, or dig up a new catfish recipe but is that really what people want? I still have a few more turkey stories to write and no doubt more information will come to me (probably around Thanksgiving), but I am running out of things to say about my favorite bird.  Should I disloyally choose a new genus to pursue.  Do you want to hear more about tiny obscure catfish? I could drop it all and move to entirely new topics, but I don’t feel right about that yet. Maybe some reorganization is needed when I launch the redesigned version of Ferrebeekeeper in the near future.

Any insight or feedback would be appreciated.  I’m sorry for the informal first person tone of this post but I am traveling today and don’t have time to research an appropriate column.  Also catfish and turkey fans should not give up yet, I still have a handful of ideas left about those magnificent creatures (not to mention a stirring Siluriforme overview).

Thanks.

Lima Shovelnose Catfish (Sorubim lima)

A Dugong and Diver (photograph by Duane Yates)

There are about 120 living species of marine mammals (although that total may tragically become much smaller in the very near future).  Of this number, only one species is herbivorous.  The mighty dugong (Dugong dugon) is the last animal of its kind, a gentle lumbering remnant of the giant herds of sirenian grazers which once graced the world’s oceans. Dugongs are distinct from the three extant species of manatees (the world’s other remaining sirenians) in that they never require fresh water at any point of their lives.  Additionally dugongs possess fluked tails in the manner of dolphins and whales.

Dugong Range

Dugongs live in shallow tropical waters of the Indian Ocean and the Pacific Ocean.  They range from Madagascar to the Philippines, but are only common along the north coast of Australia (where conservation efforts and a limited human population have allowed them to live in peace).  Dugongs can swim in deep oceans for a limited time, but prefer to stay on continental shelves where they can feed on seagrass and marine algae.  Their all-salad diet does not prevent them from growing to substantial size: some individuals have been known to reach more than 3.5 meters in length (11 feet) and weigh over 950 kilograms (nearly a ton).  Although Dugongs can live more than seventy years, they reproduce extremely slowly.  Females gestate for over a year and then suckle their calf for around 18 months. Calves may stay with their mothers for many years after being weaned and need almost contact with their mothers for security and affection until they are almost grown. Young dugongs swim with their short paddle-like flippers, but adults use their tail for propulsion and only steer with their flippers.

Dugong and Calf

Dugongs have a variety of vocalizations with which they communicate.  Usually they live in small family units.  Great herds are not unknown but  seagrasses do not grow in sufficient quantity to support such numbers together for long.

Like the other sirenians, Dugongs have dense bones with almost no marrow (a feature known as pachyostosis).  It has been speculated that such heavy skeletons help them stay suspended just beneath the water in the manner of ballast.  The lungs of dugongs are extremely elongated, as are their large elaborate kidneys (which must cope with only saltwater).  Additionally, the blood of dugongs clots extremely rapidly.

Dugongs face a number of natural threats, particularly storms, parasites, and illnesses.  Because of their large size they are only preyed upon by alpha predators such as large sharks, killer whales, and salt-water crocodiles.  As with other marine animals, the greatest dangers facing dugongs come from humankind.  For millennia Dugongs have been hunted for meat, oil, and ivory. Traditional medicine from various portions of their range (wrongly) imputes magical properties to parts of their bodies. Worst of all, dugongs are frequent victims of boat collisions or are killed as by-catch by fishermen trying to catch something else.

Close-up of a Dugong (Julien Willem)

The Eocene (Illustration by Bob Hynes for the Smithsonian Institution)

The Eocene epoch (which lasted from 56 million ago to 34 million years ago) was hot!  Temperate forests ran all the way to the poles.  Steamy tropical jungles grew in the latitude where Maine is now and the equatorial regions of earth were (probably) sweltering. Tropical reefs formed in the coastal waters around a heavily forested and ice-free Antarctica. Since there was not year-round ice at each pole, the sea levels were much higher.

A Global Map of the Early Eocene (map by Dr. Ron Blakey)

The Eocene was a time when most of the contemporary mammalian orders first appeared.  The earliest artiodactyls, perissodactyls, rodents, bats, probiscideans, sirenians, and primates all originated during this time.  Of course mammals were not the only story: the Eocene was also a time of great diversification for birds and many familiar orders of avians developed then.  Reptiles begin to put the setbacks which marked the end of the Cretaceous behind them and several giant new species emerged including an immense tropical ur-python and a host of crocodiles and turtles. It is harrowing to think that the first wee dawn horses and cute little early atiodactyls were forced to contend with a 13 meter long super snakes and giant crocodilians (which flourished in the great hot swamps of Alaska), but such is the case.

Titanboa with Ancient Crocodilian (painting by Jason Bourque)

The high temperatures of the Eocene are perplexing to scientists.  By contrast, the temperatures of the Paleocene (which was the first era of the Cenezoic and had directly preceded the Eocene) were much more temperate. In fact the temperature spike of 56 million years ago seems to have ended the Paleocene and brought about the diversification of Eocene life.  The rapid warming is known as the Palaeocene-Eocene thermal maximum and scientists have been vigorously debating what caused the climate change.  An immense amount of carbon seems to have entered the atmosphere at this time, which in turn led to greenhouse warming.  It remains controversial as to how such a large quantity of carbon got into the atmosphere.  Comet/meteorite impact, massive peat fires, and volcanic activity have been suggested as triggers, however supporting evidence is lacking.  The release of globally significant quantities of hydrocarbons–which had been trapped in undersea clathrates seems like a more feasible hypothesis, as does the idea that the earth’s orbit brought the planet closer to the sun for a time.

Phenacodus, a goat-sized grazer of the Eocene era (painting by Heinrich Harder)

The end of the Eocene was also linked to the carbon cycle.  Reduced carbon dioxide in the atmosphere seems to have led to global cooling and newly evolved varieties of grasses began to invade large swaths of the world.  Additionally two massive meteor strikes in Siberia and Maryland combined with substantial volcanic activity to finish off the long hot summer. But during the Oligocene, the era which followed the Eocene, the world was a much more familiar place inhabited by orders of animals which are still here with us today (or are us–since primates first evolved during the Eocene).

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