Leech
On May 6, 2012 we were back at the pond in the woods, catching small aquatic things[1]. One of which was this:
It’s a Leech!. OK, it’s not an arthropod, but it is an invertebrate, and we caught it while looking for arthropods. And you all want to see this one anyway, right?
This particular leech varied from a bit under an inch long, to almost three inches. That’s because they are very extensible.
It could also flatten itself out and swim quite quickly by undulating through the water, or walk along surfaces like an inchworm by using the suction cups on either end of the body.
While it was pretty agile in the water, it was also able to get around out of the water, where the inching motion still worked fine.
Leeches don’t have a head as such, but one end is definitely the mouth. In this specimen, that was the narrower end that it kept waving around looking for a good attachment.
Unfortunately, I couldn’t get it to fasten the mouth end onto a flat surface to photograph the three blades that it would use to make an incision on its host. I did get a picture of its rear sucker, though, which is just a suction cup used to hold onto things. It holds on pretty tightly, too.
Leeches are basically bloodsucking earthworms[2]. They latch onto a host, cut incisions in the skin, and then suck blood for up to a couple of hours before they get satiated and drop off. I’ve never actually had one attach to me, but my mother once told me how, when they were little girls, she and her sisters used to go wading in a leech-filled stream, and would watch the leeches attach to their legs and plump up. Then they’d pull the leeches off, and presumably do away with them. Normally, a leech will try to fill up with a huge quantity of blood, and then after they drop off they’ll hide in the bottom sediments for somewhere around six months to digest it and turn it into either more leech, or baby leeches.
Aquatic leeches like this are popular fishing bait[3]. Unlike earthworms, they don’t get soggy and listless in the water, and so they are attractive to fish. And they do work well. Some years ago, when Sandy and I drove the “Circle Tour” around Lake Superior, she used leeches to catch a monster walleye in a small lake in Ontario. They’re easy to get out of the container, too – just stick in your thumb, and when they grab on, pull them back out. It takes a couple of minutes for them to get secure enough to go for a bite, so as long as you handle them fairly briskly you won’t get bitten.
There are actually a lot of kinds of leeches, and not all of them suck blood – some are predators or scavengers. They don’t all live in the water, either. In moist environments, they will hang out in the trees, and drop on you. This isn’t strictly a tropical thing, either. I’ve seen terrestrial leeches myself, in a swampy area of Tasmania (which is about as far south as Northern Michigan is north. Kind of on the cool side, in other words).
And once a leech attaches to you, there’s nothing really special you need to do to get them off (ignore the leech-removal scene in “The African Queen”, you don’t need salt. And ignore the people who suggest using a burning cigarette, too). Just peel them off and disinfect the wound. Their mouths are basically suction cups, so it is easier to peel up one edge first to break the suction than to pull them straight off, but other than that, no sweat. Or you can just wait a couple of hours, and they’ll drop off on their own.
Historically, leeches were used as a convenient method for bloodletting. Back when doctors thought that removing some of a patient’s blood was a general cure for most everything, it was easy for them to just throw on a few leeches and let them go nuts. Even now, there are some medical applications for leeches. It seems that when surgeons reattach a severed limb, there are often problems with blood accumulating in the limb because the veins to take blood out aren’t as effective as the arteries carrying blood in. So they can just put a couple of leeches on the spots where blood gets trapped to maintain circulation until the veins can finish healing. Leeches don’t carry disease, and can be raised to be quite sterile, so this actually works pretty well.
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[1] For a net, we were using a method I saw recommended by The Dragonfly Woman a while back: get a mesh kitchen strainer, and duct-tape it to the end of a long stick (broom handle or similar). This is way cheaper than the aquatic nets sold commercially, and works fine.
[2] Well, sort of. They aren’t all that closely related to earthworms – they are about as close as beetles are to butterflies.
[3] At first I had some disturbing suspicions about how one went about catching leeches, that involved dangling one’s legs over the side of a boat or something. But it turns out that you can make any of several kinds of leech traps that don’t involve using yourself for bait. This guy uses accordion-folded aluminum sheets, baited with ground, salted beef liver. His aluminum sheet looks like a printing plate from his local newspaper (usually you can just go to your local paper and buy a bundle of these for the price of aluminum scrap), but I expect that a piece of aluminum roof flashing would work just as well. Aluminum foil is probably too thin, though. Or, you can use a perforated bucket with a piece of bloody meat in it. And some people claim that the meat isn’t even necessary, and you can just sink a head of lettuce or cabbage.
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We had leeches in the lake at Lac la Biche where my dad worked as a doctor and I would take the boys on summer holidays to visit grandpa and grandma and we’d collect leeches but really I had no close up examinations of them as you have so kindly provided in this post.
Who knew that leeches were this flexible (perfect yoga specimens)? If Catherine (my yoga instructor) had a few leeches in her class than the whining students she has (me) she would be in heaven. Just today she asked us to do that curvature of the spine that your leech in photograph # 3 is performing (albeit over a rolled up yoga mat) and I had to uncoil myself without dying.
The surface of the leech in photograph # 4 is pretty neat. It looks so corrugated –almost like a sea urchin cover (whatever a sea urchin cover is).
I like the photograph (# 6) where the leech is curious (or is he simply testing the air for blood?)
The fact that you were willing to give your body for science (i.e. provide a host for the leech to feed on) is very humanitarian of you (you will do anything to forward the aims of science research wouldn’t you? I don’t think I would provide myself as a host for any other species other than the blood sucking boys I already have).
I also loved that heart warming story of your mother and leeches in her childhood. It is obvious to me that you inherited your extreme lack of entomophobia from her. I especially like the cool way your mum explained to you the business of being host to these little rubbery vampires:
Leeches are basically bloodsucking earthworms[2]. They latch onto a host, cut incisions in the skin, and then suck blood for up to a couple of hours before they get satiated and drop off. I’ve never actually had one attach to me, but my mother once told me how, when they were little girls, she and her sisters used to go wading in a leech-filled stream, and would watch the leeches attach to their legs and plump up. Then they’d pull the leeches off, and presumably do away with them. Normally, a leech will try to fill up with a huge quantity of blood, and then after they drop off they’ll hide in the bottom sediments for somewhere around six months to digest it and turn it into either more leech, or baby leeches.
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If I had had a mother who had told me stories of leeches feasting on her body as a child I doubt that I would be as chicken about bugs today as I am. Also I have passed on this aversion to buggy things to younger boy who also cannot abide a bug in the vicinity (we both wait for older boy and my husband to do the manly thing of removal).
I had no idea that there were more leeches than the ones we saw at Lac la Biche which (from a distance—in a bucket) looked like big black commas in the water. I never touched the darn things.The boys usually got tired of them and dumped them back in the lake and so, without your informative post I would have remained ignorant of the variation in leech populations or that you could use them for fishing (although who would want to eat a fish with a leech in its belly is beyond me and now that I know that the whitefish in Lac la Biche are scarfing down these creepy things I will never touch one of those fish again.
Your advice about how to remove leeches is utterly unnecessary because who would go into a lake filled with leeches? All I did a Lac la Biche (upon learning there were leeches inside the algal bloom covered lake) was to delicately dip my toes in the water while my husband bravely rowed the boys out to sea in a rubber dinghy (that was immune to leeches and their biting tools). While they rowed out into leech-infested waters, I stayed safely on shore fighting of jumping bugs of all kinds, mosquitoes, sand birds of long beaks and the occasional bear eating fish near to shore or Saskatoons (hmm…maybe it was safer in the dinghy).
In any case, I am sure you don’t want to hear any more about my summer holidays with the boys in leech infested Alberta lake country so I will end my overlong comment with insincere apologies for the endless ruminations into memory.
I like your blog because I get to write about the boys and their childhood (which now that I think about it — all the memories seem to be tightly annealed to bugs of all kinds and sorts that I do not like.)
One thing in the world I hate: leeches. Filthy little devils.
Jumbo leeches are less than $20 apiece. Mention you saw it here on Backyard Arthropod and get a free leech tote bag!
Not to mention the significant price break if you buy 50 or more! The Leeches USA page that KT links to above is oddly fascinating. One thing they don’t mention, is how they grow them under sterile conditions. Do they have an artificial diet? They have a note that, after using them to remove pooled blood from surgical patients, the leeches should not be re-used, to avoid spreading contamination between patients (they recommend dunking the leeches in isopropyl alcohol to kill them, followed by incineration). So they obviously aren’t feeding them on human blood to raise them up.
. . . or are they?