Sanguivores: Nature's Blood Drinkers
12 of the Most Interesting
Let's face it, there are a lot of ways to eat and be eaten in the animal kingdom. Feeding ranges from the sponge-like mouth parts of flies to the flat molar-like chompers of clam-eating fish like black drum. If an animal or plant exists in the world, then something feeds in or on it. This is true of animals that drink blood, also called sanguivores (sang-wa-vors). Another word for this is hermatophagy (pronounced her- mat-oh-fay-gee). Any time you see the term "--phagy" at the end of a word it means "eating". Herma comes from the Greek word "haima" or "blood" and phagein or "to eat." For today's post I want to share with you the world of sanguivores or blood drinkers. There are more than you think, and even though you may already be squirming in your seat at the though, keep an open mind. Blood is little more than water with easily digestible proteins, lipids (fats), and nutrients. To humans blood is super taboo, and gross, we see blood as "disgusting" because we're taught that it's full of diseases and should only be seen in horror films. However, in nature blood is something not to be wasted or ignored. It's the "water of life" for some animals. Here are 12 of the most interesting.
Most people think of vampire bats or ticks when they think of sanguivores, however; there are a lot of interesting animals that live by drinking blood. There are thousands of species of insects that ingest blood, along with species of fish, butterflies, and mammals. Each one is adapted to peck, scrape, or suck blood. They all have special digestive systems that allow them to ingest and digest blood too. Scientists are especially interested in leeches, bats, and mosquitoes because they use anti-coagulants in their saliva (and anesthesia) to prevent blood clotting, which allows for free blood flow from their prey. Let's look at some of these interesting species:
- Assassin Bugs (Kissing Bugs)
- Blood Drinking Spider
- Vampire Moths
- Blood Sucking Catfish
- Vampire Flying Frogs
- Vampire Finches
- Hood Mockingbirds
- Vampire Bats
This group of insects is number one on the blood-sucker list. They are ubiquitous in most temperate areas (over 2,700 species) and known to transfer diseases through their saliva, ranging from West Nile virus to malaria. Remember that only the females drink blood, males are gentle wall-flowers that usually drink nectar. Female mosquitoes detect prey through the emission of carbon dioxide, body heat, movement and smell. They have a multi-tool of 6 needles that penetrate the skin. Check out this great video:
You're going to notice a trend with the sanguivores, they all have sharp pointy teeth or snouts, ticks are no exception to this rule. The bite of a tick is very different than that of a mosquito because ticks bite and hang on, feeding for as long as possible, before dropping off. Mosquitoes pierce, suck, and fly off. This is why a tick's snout (also called a proboscis) has backward hooked barbs to hold on to flesh while it feeds. You can read all about what happens when a tick bites you on the page from National Geographic.
3. ASSASSIN BUGS (Kissing Bugs)
The family Reduviidae are a large group of insects in the order Hemiptera (true bugs). There are a lot of different types of assassin bugs, ranging from those that use termite carcasses to lure other termites for food to those that even use ant carcasses for armor. However, the most notorious of this family, found in much of the South Eastern United states, are the kissing bugs. There are 11 species in the US with the most being found in Texas, Arizona and New Mexico. They have sharp pointy snouts, like mosquitoes, and they have protozoans in their guts (single celled animals) that cause Chagas disease, which attacks a human's heart. Kissing bugs are nocturnal, feeding around the eyes or mouth at night, thus the name "kissing bugs." It's thought that Darwin may have died from Chagas disease. You can read more on this page from Texas A&M.
4. BLOOD DRINKING SPIDER
For those of us in North American we don't have to worry about this small jumping spider, Evarcha culicivora, it lives in East Africa. It doesn't really bite people, instead it eats mosquitoes, specifically preferring female mosquitoes that have just engorged on mammalian blood (human or otherwise). You can read all about it's hunting technique and preferences here or here.
I love this photo from the Vector Ecology Blog:
5. VAMPIRE MOTHS
Vampire moths belong to the genus Calyptra, and there are about 17 species in the family Erebidae. Eight of the species are recorded drinking the blood of mammals, and this includes humans, though unlike mosquitoes only the males drink blood. They're in Africa, South East Asia, India, Japan, Russia and Southern Europe. Some of the moths in this family just pierce and drink fruit juices, the others are the famed "blood drinkers." They have a sharp proboscis that they use to feed, similar to mosquitoes, but they rock back and fort as they "drill and fill" on blood. You can read all about them here.
Lamprey are often called "lamprey eels" but they're really jawless fish with big suckers for mouths. Most are filter and bottom feeders, but one species in particular, called the "sea lamprey" is anadramous (an-add-ra-mus), spending its early years in fresh water then migrating to the ocean (much like real eels). When the adults make it to the ocean they then attach their mouths, filled with razor-sharp teeth, to the sides of fish and prey. Their teeth look like a picture of something from the dune scene of Star Wars. They suck their prey dry, and it often succumbs to blood loss. Fortunately they mostly avoid humans. They look like the leeches of the sea to me.
7. BLOOD SUCKING CATFISH
Most of us in North America would consider catfish to be fairy grandfatherly looking with their long whiskers, fat belly, and penchant for eating anything. However, there's a sub-species in South America (Bolivia, Brazil, Peru, Columbia, Ecuador), that is know for sucking blood. They are called pygidiids. These catfish are long and narrow, with thin jaws, this is why they're called toothpick or vampire fish. They are clearish and small, hard to see in the brackish waters where they feed. There are urban legends about them swimming up human urethreas, but that's just an old wives tale. You can read more about them in the National Library of Medicine's report.
8. VAMPIRE FLYING FROGS
If you're looking for a frog that sucks on to the side of your neck and leaves great padded hickeys then you're thinking about the wrong creature here. The vampire frog, Rhacophorus vampyrus, lives in the rain forests of Vietnam. The adults are dull brown and live in the trunks and tops of trees in the forest, gliding around with webs between their toes. They lay their eggs in puddles of water in flowers, plants, and trees up high. The adults eat insects, but the tadpoles are the horror. They have two sets of dark black fangs. It's thought that these fangs are used to rip into the unfertilized eggs of their siblings so that they can suck the contents dry. You can read all about them here.
9. VAMPIRE FINCHES (Tweety they're not)
Vampire finches are not the idyllic Tweety Birds you think of. They are brown, plain looking, and have a great thick beak that is razor sharp. The vampire ground finch Geospiza septentrionalis lives in the Galapagos Islands and is considered endangered. It lives on the eggs and blood of other nesting shorebirds like blue and red footed boobies. When it is thirsty it uses its great thick beak to peck at the base of the tail or wings of the birds to cause bleeding. What is really strange is that the birds tolerate it. They don't react. It's thought that maybe the vampire finches were once beneficial, and pecked the ticks and parasites off the boobies, but not anymore. They can also kill booby chicks and other native birds. Check out this video.
10. HOOD MOCKING BIRDS
Of course I"m partial to this little gem because its Latin name is Mimus macdonaldi, and despite the fact that its name sounds like it should be "hooded" and not "hood" it's still a mocking bird. The hood mocking bird is native to Ecuador, Espanola, and the Galapagos. It's not very striking and like other mocking birds its mostly an omnivore, with one exception. Like the vampire finch, it will occasionally drink blood from wounded birds (sometimes causing the wounding). It's not the mocking bird's first choice but it's a choice. North American mocking birds are tame by comparison.
Alright, the name of this bird alone causes "twitters," but it's a serious sanguivore. There are two species of oxpeckers in the family Buphagidae (Boo-faga-day...even their Latin name is crazy). Most of the time when you see pictures of oxpeckers they are riding around in their native range of sub-Saharan Africa on rhinos, giraffes, and other grazing animals. It was once thought that the birds were mutualistic, getting a free snack of ticks from the grazers and the grazers had less parasites. Turns out, after several studies, that the oxpeckers aren't necessarily so beneficial, and they may even be classified as parasites. Oxpeckers specifically choose to eat ticks that are already engorged on blood, ignoring the homely skinny ones until they fatten up, like a bad version of Hansel and Gretel on a rhino's back. Oxpeckers value the juicy ticks for their nutritional properties, being filled with more blood. It's also been shown that the oxpeckers will even open up wounds on their hosts, from parasites that they've removed, to feed on the host's blood. There's a reason that the yellow-billed ones have red beaks, they're true vampires. You can read more here if you're interested.
12. VAMPIRE BATS
Vampire bats are the low hanging fruit of the vampire world because everybody knows about them, though they probably know little about the real animals, members of the leaf-nose bat family. Vampire bats are not in North America. They're native to Mexico, Central and South America. Adults weigh around 2 ounces or 22 pennies. They are small, and they don't typically "drink" human blood. Yes, they are sanguivores, but instead of drinking blood by piercing skin with their teeth and "sucking" they are really "scratchers n' lappers." They crawl on the ground toward their prey, usually chickens or livestock, scratch the animal with their teeth, and then lap the blood with a very nicely numbing anti-coagulant saliva. They have that split bottom lip to act like a lippy-sippy straw to help them drink. There's some neat research out of Texas Tech University about how they feed and their adaptation for drinking blood, click here to learn more. Interestingly, when one bat in a colony isn't successful in finding enough blood to see them through the night, another bat in their family/colony will share (don't ask how, you don't want to know) theirs. The following video has neat animation, but it's a bit dramatic and graphic, be forewarned:
So, I've given you the top 12 most interesting (to me) sanguivores I can think of. There are many more, and their stories are just as unusual. This piece wouldn't be complete though without at least one Monty Python reference. Run away!!!!