We all know about blood sucking bats, but did you know that of all the many types of bats, only three actually drink blood? Technically this is know as haematology, the practice of feeding on blood. And blood is actually a great food source – it’s rich in proteins and lipids, is very nutritious and, so long as you don’t over do it on one individual, you’ve got yourself an unlimited cow to milk as it were.
Mosquitoes are another well known vampire, with the females needing to drink blood in order to make eggs. It’s also common knowledge that they are responsible for the spread of malaria but what you might not know is that they, or other blood sucking flies, have been spreading it for 100 million years. Mosquitoes can also transmit sleeping sickness, typhus, river blindness and other diseases making them one of the deadliest animals in the world. In 2015, malaria alone caused 438,000 deaths and cases of dengue have increased rapidly over the last 30 years.
As an aside, the mosquito is not therefore evil and nor should it be made extinct. All animals fill niches in nature and have co-evolved to fulfil a purpose or role that isn’t always clear to us. In this case, they provide food for birds, fish, frogs and so on and are also pollinators.
Also in the fly family, we find sand flies, bat flies, black flies and midges which all enjoy a drink of blood. There are also fleas, bedbugs and ticks as well as so called “kissing bugs”, or Triatomine Bugs, which apparently get their name because they like to bite people’s faces…
We also have vampire moths who use their antenna to pierce the skin of their unlucky host and some types of butterflies are partial to a sip of blood. They can’t inflict injuries themselves so it’s more a case of coming across some spilt blood and indulging. Sticking with small critters, some worms and arthropods like blood, as do some nematodes, such as Ancylostomids which feed on blood from the gut. And leeches are well known for their blood sucking behaviour and are utilised in medicine such as to prevent blood from clotting.
Living underwater doesn’t protect you from vampires… Torpedo snails like the blood of electric rays, making small cuts and then using their proboscis to draw blood from the wound. If this doesn’t work, they will insert their proboscis into they ray’s mouth, gills or anus…
Another threat comes from the Lamprey; an eel like creature which seems perfectly designed for the blood sucking way of life… They are basically a tube with teeth… They don’t have a jaw, instead having a suction cup style mouth which contains circles of sinister teeth. These teeth are stabbed into the fish and anti clotting chemicals are secreted. This tends to result in the host dying, either from blood loss or infection, at which point the lamprey will detach and move on.
The Candiru is a parasitic cat fish that are best known for allegedly being able to travel up a stream of urine and into a man’s penis. Regardless of whether that is true or not, these tiny fish do deserve a mighty reputation. They enter the gills of larger fish to suck their blood and generally make their lives a misery. Once full of blood, they leave and burrow into the river bed to digest their meal.
And finally birds… The Hood Mockingbird likes open wounds, such as those they may find on sea lions or researchers but don’t rely just on blood. However, they do increase this behaviour during the dry season suggesting it may be motivated by the need for fluid or moisture.
Vampire finches are a bit more brutal, preferring to peck at other birds, specifically blue footed boobies, until they bleed. The boobies don’t object as much as you might expect and it’s thought the finches might once have cleaned parasites from the birds and developed a taste for blood along the way.
Oxpeckers are another blood loving bird that eats ticks and insects as well as flesh and blood from wounds on large mammals. Whether this is a mutually beneficial relationship or not seems to be a topic of debate. The oxpeckers may be helping with tick removal and grooming of spots that the mammal may not be able to reach. With regards to the blood consumption, it has been argued that it may help to keep wounds clean and prevent infection and infestation.
The practice of consuming blood has co-evolved in different species, suggesting there is an evolutionary advantage for some creatures to engage in it. And when you stop to think about it, some humans also take part in haematology… Just think about black puddings…