Leeches

I used to take care of a colony of leeches for an exhibit.  Recently the topic resurfaced and I decided to wax poetic about these nifty creatures.

Alright this is going to be a really disgusting post for some people, so reader discretion is advised.

There are freshwater, terrestrial, and marine leeches, meaning, we cannot escape from this vampire. Like earthworms, leeches are hermaphrodites (an animal or plant that has reproductive organs normally associated with both male and female sexes). Some, but not all, leeches are hematophagous, meaning having a strong taste for blood.

Humans have coexisted with this parasite for ages. Now that we have moved away from the jungle, they followed us to dwell in our drainage system, man-made lakes and artificial forest. It's a common sight to see a leech slowly making its way in the drain sometimes, feeding on unwary dogs and cats that pass by. This creature even found its way into the hospital now, where doctors utilize its blooding sucking ability to withdraw clotted or contaminated blood from patients. Leech produces a special enzyme when it bites, which prevents blood from clotting, and thus it can suck on continuously until it is full. A string-thin leech would feed furiously until becoming as thick as our thumb.

Once latched onto its victim, a leech will not release its bite easily. One recommended method of removal is using a fingernail to break the seal of the oral sucker at the anterior end of the leech, repeating with the posterior end, then flicking the leech away. As the fingernail is pushed along the person's skin against the leech, the suction of sucker's seal is broken, at which point the leech should detach its jaws.

A common but medically inadvisable technique to remove a leech is to apply a flame, a lit cigarette, salt, soap, or a caustic chemical such as alcohol, vinegar, lemon juice, insect repellent, heat rub, or certain carbonated drinks. These cause the leech to regurgitate its stomach contents into the wound and quickly detach. However, the vomit may carry disease, and thus increase the risk of infection.

Simply pulling a leech off by grasping it can also cause regurgitation, and adds risks of further tearing the wound, and leaving parts of the leech's jaw in the wound, which can also increase the risk of infection.

An externally attached leech will detach and fall off on its own when it is satiated on blood, usually in about 20 minutes (but will stay there for as long as it can).Internal attachments, such as nasal passage or vaginal attachments, are more likely to require medical intervention.

There are several cases of internal attachment happening in remote areas of the world. Three years ago, a nine-year-old girl was admitted to La Merced hospital in Peru with a headache that had lasted for two weeks and a strange “sliding sensation” in her nose. Her parents quickly discovered the source of the problem – a sizeable black worm lodged up her right nostril. They quickly sought medical help and it came in the form of Dr Renzo Arauco-Brown, who removed a seven-centimetre leech from the girl’s nose. Two more cases were found in 1997.  Both had been removed from the nostrils of young boys in 1997. Like the most recent case, these children had also been bathing in local lakes and streams, which is almost certainly how they picked up their vampire.

While most leeches are found on the skin, some also specializes in feeding on mucous membranes, such as those found in the nose, eye, vagina, anus and urethra.

As you can see, this animal will try anything in order to feed on our blood. And so, medical practitioners have come up with a way to satisfy the leeches' need, while clearing ailment off the patients. The use of leeches in medicine dates as far back as 2,500 years ago when they were used for bloodletting in ancient Egypt. All ancient civilizations practiced bloodletting including Indian and Greek civilizations. Hence, medical practitioners today have a strong reason to use this ancient method to cure sicknesses, but not for me please~ I still prefer the conventional injection-medicine method.

Isopods found in the most unusual places.

Yes you read that right.

Isopods are small marine crustaceans and not commonly a topic of blogs or household conversation.

Recently there has been a meme around the internet of an isopod on a fishes mouth. In fact, it was often presented as a guessing game and all sorts of guesses were baby fish, cleaner shrimp and all rather benevolent causes.

I knew this was not a baby fish. I didn't recognized the species initially, and the first thought that came to me was that those two were the undigested prey of the fish. But the marine biologist in me wasn't happy with the answer. Were they really the undigested prey of the fish? They looked nasty, with segmented body and evil little eyes. They have seven pairs of claws underneath their belly. SEVEN! What kind of animal that needs fourteen limbs?

So I dragged out the old Invertebrate Zoology text book for information for these animals, and ta-da! They were actually the parasitic crustacean called tongue-eating louse, Cymothoa exigua.

This animal enters fish through the gills, and attaches itself to the base of the fish's tongue. It suck the blood from the tongue, causing the tongue to slowly waste away-a condition called antropy. So it's basically eating away the fish's tongue. The louse will then attach itself to the muscle of the tongue, and the fish can use the parasite just like a normal tongue.

Image: threadless.com

The female is typically larger, and attaches itself on the tongue, while the smaller male usually attaches itself behind the female. The two creatures I found inside the fish, one of them was male and the other female.

Image: themanyfacesofspaces.com

Wikipedia says that the parasite is found mostly in the North and South American seas, until one was found in the United Kingdom in 2005, which means there are these parasites in the Atlantic as well.

Which brings me to another topic, ticks.  I hate them. Disgusting little creatures and they will be the subject of another blog entry. But these isopods remind me of tick on fish.  yeck.



info: http://www.dnr.sc.gov/marine/sertc/Isopod%20Crustaceans.pdf

The Curious Case of Mosquitoes

Life really sucks if you're a mosquito. Apart from the ability to master flight, there's no good in being a parasite--your dinner can turn around and smack you dead if you're not fast enough, and your food can cause your little body to overheat. 

Oh yeah, and some neighbors will hunt you down and suck the blood right out from your belly.

According to a study in the journal Current Biology, Chloé Lahondère and Claudio R. Lazzari found out that these little vampires excrete and hang on to a single bead of blood to reduce the heating effect via evaporation.

High temperatures can have deleterious effects on insects' physiology. But some insects are dependent on warm-blooded host. And since they do not sweat like us, there must be some kind of cooling strategy to keep them from dying.

The scientists conducted a real-time infrared thermographic analysis of mosquitoes' body temperature during feeding on both warm blood and sugar solution. They found that anopheline mosquitoes can decrease their body temperature during blood feeding thanks to evaporative cooling of fluid droplets, which are excreted and maintained at the end of the abdomen. The mosquitoes that excrete a drop of blood have lower body temperatures than those that don't.

Image: cosmosmagazine.com

But life isn't just about keeping cool at the dining table. Engorged mosquitoes have to be wary of their hungry neighbors too, because they will attempt to steal your food, right out from your belly.

A technician from the Department of Entomology, University of Georgia reported that she saw a mosquito taking blood from another engorged one.

So the scientists prepared two groups of Aedes mosquitoes; one group allowed to dine on a chicken, while another starved. Right after the feeding, the starved ones were put together with the engorged mosquitoes, which remained motionless. The scientists reported that the starved individuals were attracted to the engorged mosquitoes and attempted to feed. Some eventually succeeded in taking blood from their burdened neighbors.

Aedes aegypti feeding on an engorged Aedes aegypti. Image: "Mosquitoes Feeding On Engorged Moquitoes", A. Burns Weathersby, Hyong-Sun Ah, John W. McCall.

I ain't sure about you, but I prefer to stay human.

So as we head into summer BBQ season remember your flying friends and all the trouble they go through for a quick meal. Then smack them down.

info:

http://www.scientificamerican.com/podcast/episode.cfm?id=mosquitos-use-drop-of-blood-to-keep-11-12-15

http://citebank.org/sites/default/files/MN_V31_N1_P110-111.pdf

How The Zebra Got Its Stripes?

So the other day I was driving my kids around and they asked how did the zebra gets its stripes.

The explanation I saw from documentaries stated that zebra evolved its stripes to confuse the lion.

Lions are color blind,as are many cats,  so a group of rampaging zebras can be extremely confusing and headache-inducing. With the tall African savannah grasses, one can easily see that the stripes, combined with the tall grasses could easily break up the lines of a zebra and be confusing to predators.  Sounds right, so I figured that wrapped up that little science lesson.  But I got home and did some research on the subject.

I found an entirely plausible other reason for the strips. Gabor Horvath and colleagues from Hungary and Sweden have come up with another explanation: zebra's stripes ward off blood-sucking parasites.

Image: animals.howstuffworks.com

Like us, animals hate parasites too, and one parasite, the female horseflies (tanabids) can deliver one hell of a bite. Like female mosquitoes, they feed on mammal blood for reproduction, and they carry diseases too.Locally mosquitos transmit the dinofilaria (Heartworm) parasite to dogs and cats, so it makes sense from an evolutionary viewpoint to develop a natural "Frontline" so to speak.

Image: en.wikipedia.org

They lay their eggs on stones or vegetation close to water, guided by the horizontally polarized light reflected from the water surface. And these evil vampires are also guided to their meals via horizontally polarized light reflected from animal skin.

Image: whatis.techtarget.com

To test this, the team traveled to a horsefly-infested farm in Budapest and set up three horse model; a white, a dark, and a striped model. Interestingly, the striped model was the least attractive to horseflies. The team also varied the width, density, and angle of the stripes, and found out that narrower stripes attracted fewer tanabids.

The team pointed out that developing zebra embryos start out with a dark skin, only to develop white stripes afterwards. It's possible that evolution has favored the development of zebra stripes to confuse color-blind predators, as well as ward off blood-thirsty vampires.

Should we do the same to ward off mosquitoes? Who knows, perhaps I will develop a line of striped clothing for hikers and make a fortune warding off blood sucking insects. At the very least it may save you from a Lion attack.


info: 
Polarotactic tabanids find striped patterns with brightness and/or polarization modulation least attractive: an advantage of zebra stripes, Ádám Egri et. al, J Exp Biol 215,  March 1, 2012  736-745.