August 25 - Ixodes holocyclus

This tick, the most commonly found tick along the east coast of Australia, is sometimes called the "Paralysis Tick" due to the unusual symptoms that it can produce in some people. Ixodes holocyclus lives in the wet forests, primarily, and would prefer to feed on Australia's charismatic marsupials (koala, kangaroos, etc), but will readily take its blood meal from humans if it encounters one instead. Toxins in the tick's saliva seem to disrupt neurotransmitters and can produce paralysis in humans, dogs, or other hosts and this can even be fatal if not treated because the paralysis can include muscles for pretty important things like breathing, swallowing and circulation. That said, paralysis from these tick bites is fairly rare, as it is necessary for the tick to remain attached for many days before the toxins will have these kinds of effects, so careful inspection of yourself or pets if in the area can literally be a life-saver. The good news is that there is an antiserum that can be administered if paralysis does set on. The image is a nice example, too, of how drastically different in size a tick will be before and after their blood meals.

August 24 - Thyca crystallina

Thyca crystallina is a tiny little limpet mollusc that lives on and sucks the "blood" - the hemolymph - out of blue sea stars (Linckia laevigata). The females of this species can become permanently attached to the exoskeleton of the echinoderms and just live their happily, feeding - oh and mating - with a tiny little male, one-tenth their size, that just lives in their shells and fertilizes her eggs. One might say that they are sort of a "tick of the sea" (oh, this really ought to confuse Jessica Simpson).

The image comes from this site.

August 14 - Fahrenholzia pinnata

Fahrenholzia pinnata is a species of louse that is found sucking blood on kangaroo or jumping mice in the western U.S. The name of this genus is in honor of Heinrich Fahrenholz, who was a German entomologist who studied lice. The pattern that the evolutionary trees of parasites tend to mirror those of their hosts is now called "Fahrenholz's Rule" (though was coined by Eichler, not by Fahrenholz himself). And, lice are almost always the textbook example of this rule. This is because lice spend almost their whole lives on their hosts and become adapted to clinging to their hair to avoid being groomed away. The only time they have an opportunity to transfer from one host to another is via direct contact - which, if you're a rodent, is likely to only occur between members of the same species. This phenomenon is especially true in gophers. See the post from July 16 for more information on gopher lice.

August 2 - Gnathia trimaculata

TThe parasite for today is a parasitic isopod belonging to the family Gnathiidae - the larvae of this particular species feed upon the requiem shark (Carcharinus melanopterus). There are many different species of gnathiids parasitising many different species of fish, and they have an interesting life-cycle which involve "protelian parasitism" where only the juvenile stages (called a praniza) are parasitic, while the adult stages are free-living. They go through several stages of development, alternating between feeding and non-feeding developing stages (when they are engorged with blood) before reaching sexual maturity.

They are almost like a functional equivalent of ticks for fishes - they wait in ambush for a passing host, and when one arrives, it climbs onboard, sucks blood for a few days until full, then drops off to develop into the next stage. And like ticks, they can also act as vectors which can transmit blood parasites between the fishes they feed upon.

The photo shows a pair of third-stage pranizae, scale bar is 1 mm and it came from this paper:

Coetzee, M.L., Smit, N.J., Grutter, A.S., Davies, A.J. (2009) Gnathia trimaculata n. sp. (Crustacea: Isopoda: Gnathiidae), an ectoparasite found parasitising requiem sharks from off Lizard Island, Great Barrier Reef, Australia. Systematic Parasitology 79:97-112


Contributed by Tommy Leung.

July 29 - Haematopinus quadripertusus

Haematopinus quadripertusus, commonly called the cattle tail louse, get its name because, well, because it lives on the tails of cattle. These lice will actually take their blood meals from both ends of the cow, however, and can also be found on the mouth and in the ears as well as some of the soft bits on the backside. This louse was introduced into the Southern U.S. and is now a major pest of cattle in Florida, where they can cause anemia and weight loss - not something you want if you're trying to fatten up your cattle. Lice can spread from cow to cow when they are in close contact or via rubbing on the same thing such as a post. But, the lice can also colonize completely different herds of cattle by hitching rides on flies!

Image from this site, which has additional information on these parasites.

July 24 - Lepeophtheirus salmonis

Here's another species of parasitic copepod, but this one's not going to fish eyes - just feeding off the skin, mucus, and blood of its hosts. Lepeophtheirus salmonis is the salmon louse, which, as the name suggests, infects salmon and marine species of trout. These parasites can cause a great deal of morbidity in their fish hosts and may have severe consequences for both wild and farmed fish populations as very heavy infections of these parasites can kill the hosts. You can read more about these parasites on this site, which is also the source of the image.

July 17 - Lipoptena cervi

Lipoptena cervi is the deer ked or deer fly, a blood-feeding hippoboscid fly that is native to Europe and Asia, but has been introduced into the U.S. where it feeds on white-tailed deer and elk. Female flies only produce one larva at a time, but nurse it from milk glands within until it is ready to pupate. When the adult fly emerges, it seeks out a new host and takes up residence. It even goes so far as to lose its wings once it has its new mammalian permanent address. L. cervi is fairly specific to deer, but will occasionally bite dogs or humans - and it's said to be a painful bite when it does.

July 16 - Geomydoecus coronadoi

Pocket gophers are fossorial rodents belonging to the family Geomyidae. These New World rodents build complicated underground burrow systems, producing multiple mounds of excavated soil at the surface, and often wreaking havoc to agricultural crops and pastures. Pocket gopher individuals live in small, isolated populations generally living solitary lifestyles, with one gopher occupying a burrow system. All pocket gophers have external fur-lined cheek pouches that they use to carry food (hence the name “pocket”). Another thing that pocket gophers have in common is that they are parasitized by chewing lice (Phthiraptera: Ischnocera). Chewing lice are wingless insects and obligate and permanent ectoparasites; they cannot survive for long periods of time off their hosts. There are approximately 122 species and subspecies of these ectoparasitic chewing lice (belonging to the genera Geomydoecus and/or Thomomydoecus) and given the solitary lifestyle of their hosts in conjunction with their own limited dispersal abilities, gopher chewing lice are highly host specific. The close association between these wingless ectoparasites and their hosts has enabled the gopher-louse system to become a model system for studies of cospeciation. The pocket-gopher louse assemblage has been examined for almost 30 years using various types of data including distributional information, hosts associations, allozymes, and DNA sequences. Repeated statistical comparisons have shown that pocket gophers and their lice have been cospeciating over evolutionary time with lice often showing increased evolutionary rates. Current research includes additional examination of cospeciation at various taxonomic levels, and studies of parasite ecology, parasite transmission, and coadaptation enabling the gopher-louse assemblage to continues to be a model system in evolutionary biology. The species shown here is Geomydoecus coronadoi.

Post and photo contributed by Jessica Light.

July 2 - Argas persicus

Argas persicus is a species of soft-bodied tick (Argasidae) that is common on chickens and other poultry. They like to hide in the wooden parts of the coops and then crawl onto the birds to feed. They can vector a species of bacteria called Borrelia anserina, which produces avian spirochetosis. Soft-bodied ticks aren't really so soft - they just are called that since they look rather shriveled until they fill themselves up with blood.

The image comes from this site.

June 6 - Dermanyssus gallinae

Dermanyssus gallinae, or the red mite, is an ectoparasite of birds. They do not live on birds, but rather hop on them to feed on their blood at night, while they are sleeping. They can be major pests for chicken and other poultry farmers. They will occasionally take blood meals from mammals, even humans, if they work with or live near birds.

June 4 - Lernaeocera branchialis

Life is about dealing with changes, but for Lernaeocera branchialis, some of those changes are pretty profound. This parasitic copepod starts out as a free-swimming nauplius, like other crustaceans. Then, it turns into a copepodid and seeks out an intermediate host, something slow and easy to find, like a flounder. It mates with an opposite-sex copepodid on this host and then sets off to find its final host, usually a cod or haddock. It then completely metamorphosizes into a large (4 cm), red, worm-like thing with a big egg sac and "antlers". Its head remains inserted into the gills of the fish where it feeds from the blood and pumps out new eggs.

The photo is from this site.

May 22 - Placobdella parasitica

Today's parasite, the leech Placobdella parasitica is an excellent parent. Not only can it perform both motherly and fatherly duties simultaneously (it's a hermaphrodite), it also takes good care of its young. These leeches spend most of their lives on turtles, particularly snapping turtles, where they will feed on the blood primarily around the leg pits and tail (where the turtle's formidable jaws can't reach them.) They brood their young on their ventral surface protecting them there until they are big enough to feed on their own, which sometimes means transporting them to their first meal. Despite the caring nature of the leeches post reproduction, the conception of those young is actually quite violent. Leeches will stab small spermatophores into each other in a process known as traumatic insemination. Yipes.

Photo by Mark Siddall.

April 28 - Melophagus ovinus

What do you call a fly that doesn't fly? In this case, you call it a sheep ked. Melophagus ovinus is a very common ectoparasite of sheep. The adults feed off the blood of the sheep, hiding easily in the wool. The females will give "birth" to well-developed larvae, which actually feed off "milk" that is secreted by specialized glands of their mother. They then pupate, cementing the pupal case to the wool. The pupal stage will last for about a month and this stage is unfortunately resistant to any insecticides, making keds difficult to eradicate if the population is firmly established. Keds are distressing to the sheep and as they attempt to itch them, they will rub off or thin out their wool. thus pose economic threats to shepherds who find themselves struck with these pesky insects.

April 17 - Haematomyzus elephantis

The same species of louse, known as Haematomyzus elephantis, is found on both Asian and African elephants. Although it seems like a bizarre coincidence that this parasite should have a long “proboscis” like its host, the length of its mouthparts is an adaptation to penetrate the thick skin of the elephant. And although the ”proboscis” might also look like a giant straw to suck blood, these are not sucking lice (Anoplura) but chewing lice (Mallophaga), which feed on the epidermis. They are so highly evolved that an entire suborder (Rhynchophthirina) was created for only 3 species (the other 2 are found on warthogs).

Contributed by Mike Kinsella.

April 5 - Cimex lectularius

Ask any New Yorker what their greatest fear is and what do you think it will be? Runaway subway? Nah. Shoddy cranes? Well, maybe. But, my guess is that most will say bed bugs. These insects hatch from eggs into nymphs which are quite small and hard to see, but go through repeated moltings until they are about 5 mm in length and darker brown. They live in mattresses, bedding, and furniture and emerge at night to take a blood meal from a sleeping human, which they are attracted to because of the body heat and carbon dioxide. To get the blood, they insert their proboscis, and pump saliva and anticoagulants into the wound (shown in purple in the colorized micrograph). With the other part of their mouthparts (in red), they suck blood up. In recent times, bedbugs have become something of an epidemic, both in New York and globally as well. This is likely due to a decrease use in pesticides (for fighting cockroaches) and the fact the travelers spread them so easily in bedding (do *not* bring your favorite pillow to hotels!), luggage, or sometimes clothing or pets. They are extremely hard to get rid of because they are so good at hiding in very small, tight spots. Recently, dogs have been trained to sniff them out in apartments and hotels, which is helping with their extermination.

There is lots more info on bedbugs, including their historical association with humans and the best methods for detecting them and getting rid of them on their Wikipedia page.

Ok, I'm itchy now.

Image is from the CDC Public Health Image Library.

March 23 - Argulus foliaceus

Argulus foliaceus, also known as the common fish louse or the carp louse, is actually not a louse or even an insect at all, but a crustacean. Within the class Maxillopoda, the subclass Branchiura consists of about 150 species of freshwater and marine fish ectoparasites. The genus Argulus is found throughout the world. Argulus foliaceus is native to Europe, but is also common on aquarium and pond fish worldwide. Although the louse shows some host preference, especially for carp, it is usually considered a generalist and is found on a variety of fish species. The oval-shaped, flat adults attach to fish hosts using hooked suckers. They inject digestive enzymes into the host and feed on blood and tissue fluids. Symptoms of lice infestation include abnormal swimming, rubbing, and deteriorating physical condition. Because of tissue damage caused by the parasite, secondary bacterial and fungal infections frequently occur. Adult females leave their hosts and lay eggs on vegetation or other submerged objects. Adults can live free of hosts for two to three weeks, but newly hatched larvae only survive a couple of days if they do not find a host. Treating an infested aquarium may require several approaches, so prevention is best. Always visually inspect and quarantine new fish. Lice may be removed from fish manually with forceps. Fish should be transferred to an alternate aquarium while chemical treatments are used to kill remaining adults, larvae, and eggs.

Contributed by Elizabeth McCarthy, Bucknell University.
Photo from this site.

March 16 – Cyclopodia horsfieldi

Huh? A flightless fly? These highly specialized bat flies (Diptera: Hippoboscoidea) feed exclusively on the blood of bats and live their lives clinging mightily to the fur of their volant hosts. Although considered true flies, these derived creatures have lost their wings entirely and evolved specialized structures for ‘swimming’ through or ‘running’ across the fur of their hosts. They have a bizarre life-history, bat flies do not lay eggs, but rather eggs develop internally within the females nourished by uterine “milk” and a single prepupa (3rd instar larva) is deposited on the roost substrate. When young flies emerge, they crawl on to the nearest bat and live out the rest of their life on their host. Interestingly, bat flies are generally quite host-specific but Cyclopodia horsfieldi is known to occur on three species of “flying fox”, or Old-World fruit bats (Pteropus), found in Southeast Asia. If bats aren’t your cup of tea, then an experience with the World’s largest bats teaming with a bunch of wingless blood-sucking flies is sure to induce nightmares!

Contributed by Kevin Olival.

March 13 – Ixodes scapularis

Ixodes scapularis, the blacklegged or deer tick, is a hard-bodied (ixodid) tick that is common across the eastern and Midwestern U.S. These ticks have become recognized as important vectors of several emerging diseases, most notably Lyme Disease, but also Babesia and Anaplasma. Like many other ticks (see Dermacentor variabilis, for example), the life cycle of I. scapularis involves three stages: a larva, a nymph, and an adult. Larval and nymphal I. scapularis often take their blood meals from deermice, but the adults favor larger mammals, particularly white-tailed deer. Humans (and domestic animals) can become infected when they are accidental hosts to nymphal or adult ticks that became infected when they acquired the bacterial or protozoan parasites from their first or second hosts.

March 6 - Ctenocephalides felis

The cat flea, Ctenocephalides felis, is by no means restricted to just cats. In fact, it is quite happy taking blood meals from just about any warm-blooded mammal, though it is in fact, most commonly found on cats and dogs. Adult fleas take blood meals from their mammalian hosts and then lay their eggs on the host’s fur. The eggs don’t usually stick there, though and will fall out with the fur into the bedding or other environment. Larvae hatch out of the eggs and then will begin to eat just about anything organic lying around – commonly their parents’ feces, which are of course made of dried blood (shown in photo). The larvae will eventually spin a cocoon and pupate and then the adult pops out and looks for a mammal so it can start feeding. Generally, C. felis does not cause many problems, other than the annoyance of feeling them jump around and bite and the allergic reactions that occur in some animals and people. They do transmit a worm, however. We will meet that parasite tomorrow.

February 11 - Pediculus humanus humanus

In honor of "Fashion Week" in New York this week, six of the posts this coming week will involve parasites that relate to fashion in some way.

Today's: Body lice - I thought it would be fitting to start with these little creatures, which are a little "bonus" that we acquired when humans began to wear clothes.

Body lice, Pediculus humanus humanus (also called clothing lice) are believed to have evolved from head lice, likely invading the body region only recently with the advent of clothing use in modern humans. These wingless insects are found on the body and in clothing and prefer to attach their eggs to clothing rather than body hair. Compared to head lice, body lice are less prevalent parasites, associated mainly with those living in poor conditions in colder climates. Body lice are, however, potentially more harmful because they are known vectors of at least three bacterial pathogens in humans: Rickettsia prowazekii (epidemic or louse-borne typhus), Borrelia recurrentis (louse-borne relapsing fever) and Bartonella quintana (trench fever). Body lice, and the diseases they carry, can be transmitted fairly easily and quickly, especially in crowded situations such as war. In fact, body lice are known to have been prevalent amongst soldiers in Napoleon’s Grand Army and it’s possible that the diseases they carried may have played a role in the French retreat from Russia.

Contributed by Jessica Light.
Image from the CDC Public Health Image Library.