Sometimes they make us scream and run for the nearest makeshift weapon. And other times we marvel at their adaptions, tenacity, beauty and taste (yum yum).
In some cases the benefit they provide to humankind is obvious, and people feel a genuine sense of concern when their populations are threatened. And in other cases not so much.
I don't know about you, but I've certainly wondered what possible purpose do mosquitoes serve?
I' m like a magnet for those blood suckers. And I swell right up from their bites. And they spread horrible diseases like malaria in humans (Interesting side-note on malaria, see below *) and heartworm in dogs. And make evenings in front of the campfire or any otherwise enjoyable summer time activity, less so.
And then there is the house centipede, those creepy crawly critters with far too many legs that appear in our basements at night. When I was researching this subject, one reference told of auto-mimicry in the house centipede, and how this makes it difficult to tell their front from their back. Okay, kind of interesting perhaps. Still, I don't think that tidbit alone will alter my reaction when I see them scurrying across the floor.
So, in the interest of knowledge and understanding and impartiality, today I thought I'd take a closer look at two of my least favourite arthropods, the house centipede and the mosquito.
*I remember learning in high school about the relationship between malaria and sickle-cell anemia. That is, how some individuals with sickle-cell anemia were protected from malaria. Well, they have worked out the how and why of this relationship. Check it out:
http://www.nature.com/news/sickle-cell-mystery-solved-1.9342
MOSQUITOES
How that question is answered (in terms of it being beneficial or detrimental) depends upon who you ask.
It is true that mosquitoes comprise a large portion of the diet of some species of spiders, insects and amphibians. Still, when weighing the pros and cons of their existence, for many, the scales are heavily tipped on the con side.
And as is always the case when speaking of such scenarios, it becomes a game of ecological Jenga.
The ecosystems of the Arctic tundra are among those with the potential to experience several negative consequences were the mosquito to disappear.
In springtime, the hatchlings of a mosquito species native to this region swarm the caribou to feast on their blood. It has been suggested that the migratory path of the caribou is one taken in an effort to avoid these swarms. And thus, in the absence of the swarms, migratory paths might be altered, which in turn would impact the flora and fauna habituated to their passage.
Still, one might argue that such ecosystem disruptions as described above would eventually sort themselves out. And on the plus side, the world would have lost a major **vector of disease transmission.
But then again, the thing with Jenga is: we just can't know for certain the impact of our actions until it's too late.
**Different species of mosquitoes have been confirmed as vectors for such diseases as: yellow fever, dengue fever, chikungunya, malaria and West Nile virus.
And in case anyone was wondering, the transmission of HIV virus by mosquitoes is at worst extremely unlikely.[1]
Some interesting Mosquito facts:
The female mosquito is the one that consumes blood. Her mouth parts are constructed so that they can pierce the skin. She requires the additional nutrients from blood to produce her eggs. Both males and females feed on flower nectar. (Source: The Library of Congress)
The feeding preferences of mosquitos include those with type O blood, heavy breathers, those with a lot of skin bacteria, people with a lot of body heat, and the pregnant.[2][3]
Additionally, the preferred victim's sweat simply smells better to the mosquito than others because of the proportions of the carbon dioxide, octenol and other compounds that make up body odor.[4]
THE HOUSE CENTIPEDE
Well, it's like I said above, because at night I often see guys that look like the handsome fellow on the left, scurrying across my basement floor, and up the walls, and probably into my ears at night like Chekhov in the Wrath of Khan. And because, I think it means something when my terrier, who will slay the meatiest spider, won't go anywhere near these critters, even after I've squished it.
Interesting facts about the House Centipede: [5, 8-10]
- They are insectivores; meaning, they feed on spiders, bed bugs, termites, cockroaches, silverfish, ants, and other household arthropods. They are typically a yellowish-grey centipede with up to 15 pairs of legs.
- They administer venom through modified legs (forcipules).
- They are mostly nocturnal hunters.
- Their antennae are sensitive to both smells and tactile information.
- They use both their mandibles and their legs for holding prey. This way they can deal with several small insects at the same time.
- To capture prey, they will either jump onto it or use their legs in a technique described as "lassoing".
- They've adapted their feeding strategies to the hazard the prey might pose to them. For wasps, they retreat after applying the venom to give it time to take effect.
- When the centipede is in danger of becoming prey itself, it can detach any legs that have become trapped.
- They are generally considered harmless to humans. Bites (stings) are extremely uncommon, and the forcipules of most house centipedes are not strong enough to penetrate human skin. Stings are generally no worse than a bee's sting, with its venom causing redness and mild to severe swelling.
- They are prone to dehydration which is why they tend to live in damp or humid places.
Oh, and if you found that at all unsettling, just be glad you don't live in South America where these bad boys make their home:Scolopendra gigantean, also known as the Amazonian giant centipede, is the largest existing species of centipede in the world, reaching over 30 cm (12 in) in length. [10]
It is known to eat lizards, frogs, birds, mice, and even bats, catching them in midflight,[7] as well as rodents and spiders.
(Source: Wikipedia)
During the Carboniferous Period (~300 mi. yrs. ago), insects were quite a bit larger than they are today, with some giant dragonfly-like forms reaching wingspans of 55 to 70 cm. [11]
This gigantism may have been due to higher atmospheric oxygen levels that allowed increased respiratory efficiency relative to today. The atmospheric content of oxygen also reached their highest levels in history during the period, 35%[6] compared with 21% today. [11]
The lack of flying vertebrates could have been another factor contributing to their size. (You know, 'cause it gets crowded up there.)
And lastly, in a demonstration that Arthropods are not without a sense of irony: http://time.com/3018265/george-harrison-memorial-tree-beetles/
UPDATES / RELATED
Giant Redheaded Centipede Photo Goes Viral, Horrifies the Internet / Live Science / July 10, 2015
How To Keep Mosquitoes Away: Consumer Reports Reviews Bug Sprays, Says DEET Is Not The Winner / Medical Daily / May 13, 2015
REFERENCES
[1] "Can I get HIV from mosquitoes?". CDC. October 20, 2006.
[2] Shirai Y, Funada H, Seki T, Morohashi M, Kamimura K (July 2004). "Landing preference of Aedes albopictus (Diptera: Culicidae) on human skin among ABO blood groups, secretors or nonsecretors, and ABH antigens". Journal of Medical Entomology 41 (4): 796–9. doi:10.1603/0022-2585-41.4.796. PMID 15311477.
[3] Bill Chappell (July 12, 2013). "5 Stars: A Mosquito's Idea Of A Delicious Human".
[4] Hallem EA, Nicole Fox A, Zwiebel LJ, Carlson JR (2004). "Olfaction: Mosquito receptor for human-sweat odorant". Nature 427 (6971): 212–213. doi:10.1038/427212a.[5] J.G.E. Lewis (2007), The Biology of Centipedes. Cambridge: Cambridge University Press. ISBN 0-521-23413-1 pp. 185–186.
[6] Beerling, David (2007). The emerald planet: how plants changed Earth's history. Oxford University press. p. 47. ISBN 9780192806024.
[7] Molinari, Jesús; Gutiérrez, Eliécer E.; de Ascenção, Antonio A.; Nassar, Jafet M.; Arends, Alexis; Márquez, Robert J. (2005). "Predation by giant centipedes, Scolopendra gigantea, on three species of bats in a Venezuelan cave" (PDF). Caribbean Journal of Science 4 (2): 340–346.
[8] Eric R. Eaton (2007). Kaufman Field Guide to Insects of North America. HMCo Field Guides. p. 26. ISBN 0-618-15310-1.
[9] Jeffrey K. Barnes (2003). "House Centipede".
[10] http://en.wikipedia.org/wiki/Centipede[11] http://en.wikipedia.org/wiki/Carboniferous
http://www.insects.org/
http://en.wikipedia.org/wiki/Scutigera_coleoptrata
http://www.loc.gov/rr/scitech/mysteries/mosquitoes.html
http://www.nature.com/news/2010/100721/full/466432a.html
http://eol.org/collections/38915
http://www.nature.com/news/sickle-cell-mystery-solved-1.9342
http://en.wikipedia.org/wiki/Mosquito
http://en.wikipedia.org/wiki/Insect
http://www.si.edu/Encyclopedia_SI/nmnh/buginfo/bugnos.htm
http://sciencecastle.com/sc/index.php/animalspecies/showclasses
http://en.wikipedia.org/wiki/Arthropod
IMAGE CREDITS
(In order of appearance)
"Arthropoda" by Kolihapeltis 01 Pengo.jpg: Peter HalaszStylonurus BW.jpg: Nobu TamuraSCORPIO MAURUS PALMATUS.jpg: Guy HaimovitchBlue crab on market in Piraeus - Callinectes sapidus Rathbun 20020819-317.jpg: WpoppFemale centipede with eggs.jpg: Marshal HedinJohn Kratz - Swallowtail (by-sa).jpg: John Kratzderivative work: Xvazquez, Amada44 - Kolihapeltis 01 Pengo.jpgStylonurus BW.jpgSCORPIO MAURUS PALMATUS.jpgBlue crab on market in Piraeus - Callinectes sapidus Rathbun 20020819-317.jpgFemale centipede with eggs.jpgJohn Kratz - Swallowtail (by-sa).jpg. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Arthropoda.jpg#mediaviewer/File:Arthropoda.jpg
"Anopheles stephensi" by Jim Gathany - This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL), with identification number #5814.Note: Not all PHIL images are public domain; be sure to check copyright status and credit authors and content providers.English | Slovenščina | +/−. Licensed under Public domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Anopheles_stephensi.jpeg#mediaviewer/File:Anopheles_stephensi.jpeg
"Scutigera coleoptrata" by Bruce Marlin - Own work http://www.cirrusimage.com/centipedes_millipedes.htm. Licensed under Creative Commons Attribution 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Scutigera_coleoptrata.JPG#mediaviewer/File:Scutigera_coleoptrata.JPG
"Centipede, Trinidad". Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Centipede,_Trinidad.jpg#mediaviewer/File:Centipede,_Trinidad.jpg
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