by Bill Schutt
Additionally, once vampires have situated themselves within striking distance, they inflict relatively painless bites with an array of razor-sharp cutting instruments. These include denticles (leeches), chelicerae (mites, ticks, chiggers), needlelike stylets (mosquitoes and other insects), and actual teeth (vampire bats). The sharpened nature of these structures allows the vampires to gain access to the blood of their hosts without causing alarm, but even so, the complications encountered during a blood meal are far from over.
One major problem that all vampires must overcome is hemostasis, or blood clotting. This process actually consists of a maddeningly complex cascade of chemical reactions that must occur before a clot forms.*153 For the creature carrying around all that blood, the key benefit to this hemostatic complexity is that it prevents blood from clotting where and when it shouldn’t. The downside to the clotting cascade is that it has enabled blood feeders to interfere with the clotting process at multiple points along the chemical pathway. In other words, if there were only one step in the clotting process where the potential blood feeder could thwart the process, the odds of evolving that ability would be pretty low. But if blood clotting can be disrupted at any one of many points in a complex chemical cascade, the odds would be much higher that such a clot-disrupting substance would evolve. As a result, although each vampire has its own separately evolved anticlotting substances, the outcome is identical—freely flowing blood from the prey, with clot formation delayed until after (sometimes long after) a blood meal has been obtained.
Considering how long their “manufacturers” have been in business, these natural anticoagulants are often far more efficient than anything produced by man, and several of them have become important medications. For example, the clot-dissolving properties of the vampire bat–derived substance desmokinase have been used to combat strokes, while hirudin, an anticoagulant found in leech saliva, is used to prevent blood clots from forming after hip replacement surgery. Additional vampire-derived compounds (like anesthetics, perhaps) have tremendous potential for use in the field of medicine and we can certainly expect to hear more about them as researchers explore the field.
But besides a potential for providing us with some useful pharmacological products, do blood feeders provide any additional benefits?
The answer is most certainly yes.
Vampire bats remain great examples for learning about the pitfalls of scientific discovery, especially how problems can arise when prejudice and misinterpretation substitute for careful observation and experimentation. Unfortunately, some of these early errors have perpetuated a slew of misconceptions about bats (although the next time someone implies that most bats are blood feeders, you’ll be ready to pounce). Each year, thousands upon thousands of beneficial bats are killed because of fear and ignorance, and the problems that do exist with vampire bats (generally, Desmodus) are actually the result of man’s destruction of the natural environment, combined with our dogged insistence on propagating domestic animals in places where they just don’t belong. Desmodus and its cousins, Diaemus and Diphylla, display an amazing array of adaptations for their blood-feeding lifestyles and as such they are poor representatives for bats as a group. Far more typically, bats help reduce the number of harmful insects, pollinate plants that are essential to their ecosystems (and to humans), and help to reforest tropical regions shattered by slash-and-burn agriculture.
On another very important level, sanguivores provide food for a variety of other creatures. Leeches, for example, are a preferred meal of many species of freshwater fishes, a fact hasn’t gone unnoticed by the fishing bait industry (one company offers a discount for leech orders over twenty-five pounds). Fishermen use leeches to catch game fish such as walleye (Sander vitreus), smallmouth bass (Micropterus dolomieu), and northern pike (Esox lucius), as well as smaller pan fish like bluegills (Lepomis macrochirus). Mosquitoes are another important food source, especially for birds and bats.*154 Mites, ticks, and chiggers are also eaten, and even bed bugs are food for some insects, including several species of ants.
Although I’m unaware of any studies on this issue, it’s likely that blood feeders also serve an additional ecological role: namely, to cull out the old and the sick from prey or host populations. A moose that is able to emerge alive from a winter’s stint as a “ghost moose” might very well be carrying around a genetic blueprint with an amped-up emphasis on surviving harsh conditions (especially since the ticks do not feed on the moose during the summer). On the other hand, moose that die from winter tick infestations apparently do so from starvation (distracted from feeding by all that grooming and rubbing). Hypothetically at least, not only might that moose be carrying “inferior” genes, but its death would leave more food for heartier individuals and those unaffected by the tick onslaught.
Rather than wishing for blood-feeding creatures to disappear, or starting to twitch at their very mention, we should be dealing with the fact that vampires are here and they’re probably here to stay. In that regard, some of these blood-feeding creatures, like mosquitoes, can be deadly enemies and should be treated as such—although I am certainly not advocating the wholesale application of pesticides. Other sanguivores, like the common vampire bat, bed bugs, ticks, and chiggers, can become serious problems—some of them with the potential to sicken or even kill us. We should keep in mind, however, that in most cases these vampires would rather be feeding on something other than humans and it’s generally our fault when we encounter them.
Then there are blood feeders that have a high gross-out quotient but are basically harmless (at least to humans). Leeches fall neatly into this category, as do candirus (except on extremely rare occasions).
Finally, there are some vampires that will certainly require our help if they are to avoid extinction over the next few decades. The bird-biting vampire bats Diaemus and Diphylla immediately come to mind. In my opinion, even if you’re not a fan of these creatures, with only five thousand species of mammals, we should not stand by as two of them disappear forever. It should also be stressed that conservation measures shouldn’t be limited to vertebrate blood feeders. As researchers like Mark Siddall have recently shown, there are invertebrate species, such as the misclassified leech Hirudo verbana, that appear to have squirmed through the cracks in our wildlife protection laws.
In the words of Edward O. Wilson:
We should judge every scrap of biodiversity as priceless while we learn to use it and come to understand what it means to humanity. We should not knowingly allow any species or race to go extinct. And let us go beyond mere salvage to begin the restoration of natural environments, in order to enlarge wild populations and stanch the hemorrhaging of biological wealth. There can be no purpose more enspiriting than to begin the age of restoration, reweaving the wondrous diversity of life that still surrounds us.
The tragedy of extinction is that not only do organisms disappear before we know the answers to our questions, they sometimes disappear before we know the right questions to ask.
NOTES
1: WALLERFIELD
In 1933 Greenhall and Raymond Ditmars Raymond L. Ditmars and Arthur M. Greenhall, “The Vampire Bat—A Presentation of Undescribed Habits and Review of Its History,” Zoologica 4 (1935): 53–76.
Heavily loaded down after a blood meal J. Scott Altenbach, Locomotor Morphology of the Vampire Bat, Desmodus rotundus, Special Pub. No. 6, American Society of Mammalogists (Lawrence, Kans.: 1979), 19–30.
It had taken me six months William A. Schutt Jr., John Hermanson, Young-Hui Chang, Dennis Cullinane, J. Scott Altenbach, Farouk Muradali, and John Bertram, “Functional Morphology of the Common Vampire Bat, Desmodus rotundus,” Journal of Experimental Biology 200, no. 23 (1977): 3003–12.
In 1941 Captain Lloyd Gates David E. Brown, Vampiro—The Vampire Bat in Fact and Fantasy (Silver City, N. Mex.: High-Lonesome Books, 1994), 77.
2: CHILDREN OF THE NIGHT
In 1801, in Paraguay David E. Brown. Vampiro—The Vampire Bat in Fact
and Fantasy (Silver City, N. Mex.: High-Lonesome Books, 1994), 15.
The vampire bat is often the cause Charles R. Darwin, A Naturalist’s Voyage (London: John Murray, 1886), 22.
This is an adaptation that comes in handy Uwe Schmidt, “Orientation and Sensory Functions in Desmodus rotundus,” in Natural History of Vampire Bats, ed. A. M. Greenhall and U. Schmidt, 150–52 (Boca Raton, Fl.: CRC Press, 1988).
A recent study suggests that Desmodus Udo Gröger and Lutz Wiegrebe, “Classification of Human Breathing Sounds by the Common Vampire Bat, Desmodus rotundus, BMC Biology, 4, no. 18 (2006): 1–8.
For example, Muslim gypsies in the Balkans Matthew Bunson, The Vampire Encyclopedia (New York: Gramercy, 1993), 218, 278.
In Victorian England Jerry Hopkins, Extreme Cuisine (North Clarendon, Vt.: Tuttle Publishing, 2004), 269.
A boy by the name of Ernest Wicks Montague Summers, The Vampire: His Kith and Kin (London: Kegan Paul, Trench Trubner and Co., 1928), 46.
Vlad’s favorite torture method Radu Florescu and Raymond T. McNally, Dracula—A Biography of Vlad the Impaler (New York: Hawthorne Books, 1973), 76–77.
How did a murderous Romanian prince Ibid., 8–9.
Another hypothesis on the origin M. Brock Fenton, “Wounds and the Origin of Blood-Feeding in Bats, Biological Journal of the Linnean Society 47 (1992): 161–71.
As Stephen J. Gould explained Stephen Jay Gould, Wonderful Life: The Burgess Shale and the Nature of History (New York: W.W. Norton, 1989).
As an alternative to previous speculation William A. Schutt Jr., “The Chiropteran Hindlimb Morphology and the Origin of Blood Feeding in Bats, in Bat Biology and Conservation, ed. T. H. Kunz and P. Racey, 157–68. Washington, D.C.: Smithsonian Institute Press, 1998).
3: SNAPPLE, ANYONE?
Had he dissected a specimen Thomas H. Huxley, “On the Structure of the Stomach in Desmodus Rufus,” Proceedings of the Zoological Society of London 35 (1865), 386–90.
In an experiment using barium-laced cow blood G. Clay Mitchell and James R. Tigner, “The Route of Ingested Blood in the Vampire Bat,” Journal of Mammalogy 51, no. 4 (1970): 814–17.
According to a 1962 paper William A. Wimsatt and Anthony Geurriere, “Observations on the Feeding Capacities and Excretory Functions of Captive Vampire Bats,” Journal of Mammalogy 43 (1962): 17–26.
George Goodwin and Art Greenhall took George Goodwin and Arthur M. Greenhall, “A Review of the Bats of Trinidad and Tobago,” Bulletin of the American Museum of Natural History 122 (1961): 187–301.
In 1969, Cornell vampire bat expert William N. McFarland and William A. Wimsatt, “Renal Function and Its Relationship to the Ecology of the Vampire Bat, Desmodus rotundus,” Comparative Biochemistry and Physiology 28 (1970): 985–1006.
Isolated from a clover mold Robert and Michèle Root-Bernstein, Honey, Mud, Maggots, and Other Medical Marvels (New York: Houghton Mifflin, 1997), 95.
After capturing the bats in mist nets Rexford Lord, “Control of Vampire Bats,” in Natural History of Vampire Bats, ed. A. M. Greenhall and U. Schmidt, 217–20. (Boca Raton, Fl.: CRC Press, 1988).
A related, but less-cost-efficient, method Ibid., 219.
Although we didn’t realize it Bill Hayes, Five Quarts: A Personal and Natural History of Blood (New York: Random House, 2005), 172–73.
Some researchers use an alternative method Janet M. Dickson and D. G. Green, “The Vampire Bat (Desmodus rotundus): Improved Methods of Laboratory Care and Handling,” Laboratory Animals 4 (1970): 40.
During the three years that we maintained William A. Schutt Jr., Farouk Muradali, Mondol, Keith Joseph, and Kim Brockmann, “The Behavior and Maintenance of Captive White-Winged Vampire Bats,” Diaemus youngi (Phyllostomidae: Desmodontinae). Journal of Mammalogy 80, no. 1 (1999): 71–81.
Another way that Diaemus differs Arthur M. Greenhall, “Feeding Behavior,” in Natural History of Vampire Bats, 123–35.
In 1984, zoologist Gerry Wilkinson Gerald S. Wilkinson, “Reciprocal Food Sharing in the Vampire Bat,” Nature 308 (1984): 181.
So named for the frill Karl Koopman, “Systematics and Distribution,” in Natural History of Vampire Bats, 7–17.
If you examine the hind limb bones William A. Schutt Jr., “Chiropteran Hindlimb Morphology and the Origin of Blood Feeding in Bats,” in Bat Biology and Conservation, ed. T. H. Kunz and P. Racey, 157–68. (Washington, D.C.: Smithsonian Institute Press, 1998).
Researchers in the 1970s Dona Howell and J. Pylka, “Why Bats Hang Upside-Down: A Biomechanical Hypothesis,” Journal of Theoretical Biology 69 (1977): 625–31.
Many bats have a structure called a calcar William A. Schutt Jr. and Nancy B. Simmons, “Morphology and Homology of the Chiropteran Calcar,” Journal of Mammalian Evolution 5, no. 1 (1998): 1–32.
Basically, what I’d proposed was similar William A. Schutt Jr. and J. Scott Altenbach, “A Sixth Digit in Diphylla ecaudata, the Hairy-Legged Vampire Bat,” Mammalia 61, no. 2 (1997): 280–85.
Rather than feeding from below the branch J. Moojen, “Sanguivorismo de Diphylla ecaudata Spix em Gallus domesticus (L.),” O Campo 10 (1939): 70.
4: EIGHTY OUNCES
“It has been my unvaried rule” “The Death of George Washington, 1799,” Eye Witness to History, 2001, http://www.eyewitnesstohistory.com.
Soon after, the incision was made George Washington: Eyewitness Account of His Death,” 2003, http://www.doctorzebra.com/prez/z_x01death_lear_g.htm.
In desperation, Dr. Dick Oscar Reiss, Medicine and the American Revolution (Jefferson, N.C.: McFarland and Co., 1998), 234–35.
Other suggestions included rubbing Ibid., 235.
For example, some ancient Egyptians Henry E. Sigerist, A History of Medicine, vol. 1: Primitive and Archaic Medicine (New York: Oxford University Press, 1951), 247.
The word blood shows up Douglas Starr, Blood: An Epic History of Medicine and Commerce (New York: Knopf, 1998), xiv.
Since the ancient Hebrews believed Kenneth Walker, The Story of Blood (New York: Philosophical Library, 1962), 20–22.
Galen and his contemporaries used a metal scalpel Bill Hayes, Five Quarts: A Personal and Natural History of Blood (New York: Random House, 2005): 172–73.
In 1462 a bloodletting calendar Starr, Blood: An Epic History of Medicine and Commerce, 19.
Even drowning victims were bled Wendy Moore, The Knife Man (New York: Broadway Books, 2005), 187–88.
5: THE RED STUFF
Hemoglobin is so effective at carrying O2 Kenneth Walker, The Story of Blood (New York: Philosophical Library, 1962), 39.
There are so many erythrocytes Ibid., 37.
A year later, encouraged by Lower’s results Bill Hayes, Five Quarts: A Personal and Natural History of Blood (New York: Random House, 2005), 52.
Then he received about six ounces Douglas Starr, Blood: An Epic History of Medicine and Commerce (New York: Knopf, 1998), 3–16.
Aneurysms can occur for any Robert and Michèle Root-Bernstein, Honey, Mud, Maggots, and Other Medical Marvels (New York: Houghton Mifflin, 1997), 78–79.
Bloodletting was also used Ibid., 80.
In his book Blood: An Epic History of Medicine and Commerce Ibid., 15–16.
Porphyria (from the Greek word for “purple”) Matthew Bunson, The Vampire Encyclopedia (New York: Gramercy, 1993), 210.
In the 1960s two authors I. Macalpine and R. Hunter, “The Insanity of George III: A Classic Case of Porphyria,” British Medical Journal 1 (1966): 65–67.
The examination of several strands BBC News, King George III: Mad or Misunderstood, http://news.bbc.co.uk/go/pr/fr/-/hi/health/388903.stm, 2004.
Recently, researchers have found evidence Andrew Bowser, “DG Dispatch—DDW: Blood-letting Improves Hepatitis C Patient Response to Interferon,” May 19, 1999, http://pslgroup.com/dg/fead6.htm.
Studies have shown that insulin resistance J. M. Fernandez-Real, G. Penarroja, A. Castro, F. Garcia-Bragado, I. Hernandez-Aguado, and W. Ricart, “Blood Letting in High-Ferritin Type 2 Diabe
tes: Effects on Insulin Sensitivity and Beta-Cell Function,” Diabetes 51, no. 4 (2002): 1000–4.
6: A BEAUTIFUL FRIENDSHIP
One Trinidadian genus has Roy T. Sawyer, Leech Biology and Behavior, vol. 1: Anatomy, Physiology, and Behaviour (Oxford, England: Clarendon Press, 1986), 368.
Leeches are commonly fed upon James H. Thorp and Alan P. Covich, eds., Ecology and Classification of North American Freshwater Invertebrates (New York: Academic Press, 1991), 428.
Among these are several members Roy T. Sawyer, Leech Biology and Behavior, vol. 2: Feeding Biology, Ecology, and Systematics (Oxford, England: Clarendon Press, 1986), 430–32.
Although the hard outer covering Thorp and Covich, Ecology and Classification of North American Freshwater Invertebrates, 451–52.
Additionally, leeches were the preferred method Robert and Michèle Root-Bernstein, Honey, Mud, Maggots, and Other Medical Marvels (New York: Houghton Mifflin, 1997), 90.
Medicinal leech use reached its zenith Ibid.
Fashion-conscious ladies “Hirudo medicinalis, Leech History, http://www.leeches-medicinalis.com/history.htm, 2006.
The Leech-gatherers take them J. G. Wood, Animate Creation: A Popular Edition of Our Living World: a Natural History, vol. 3 (New York: Selmar Hess, 1885), 598.
Like many freshwater leeches Sawyer, Leech Biology and Behavior, vol. 2: Feeding Biology, Ecology, and Systematics, 626–27.
This behavior is similar to that reported M. R. Heupel, C. A. Simpfendorfer, and R. E. Hueter, “Running Before the Storm: Blacktip Sharks Respond to Falling Barometric Pressure Associated with Tropical Storm Gabrielle,” Journal of Fish Biology 63, no. 5 (2003): 1357–63.
Leeches were also commonly used to treat strokes A. Mark Clarfield, “Stalin’s Death (or ‘Death of a Tyrant’),” Annals of Long-Term Care 13, no. 3 (March 2005): 52–54.
Summoned, some contend, up to thirteen hours Edvard Radzinsky, Stalin (New York: Doubleday, 1996), 574.
