An October Willamette sanguivore

[Tanya Lasswell]

Hi all,

I'm pretty new to the WV, and very much enjoying this list!

While I'm a botanist first and foremost, I am delighting in the wonderful diversity here. One of my *very* weak spots of knowledge, however, is in the realm of leeches. After encountering land leeches dropping from trees in southern Thailand (and then a colleague was rather abruptly divorced by a leech systematist), I really didn't have much interest in seeking them out again. (*shudder*)

But, my family is always happy to bring me unusual bits of diversity. Yesterday, they brought me this video they'd made of a leech at Sunset Park and Natural Area, between Corvallis and Philomath. While I did my best with the leech keys available online, I admit that my ID is really mostly a guess (Find in page -> "transparent" and "green" was far more useful than using a key, at least for me).

If the lovely little jade-colored bloodsucker is indeed in the genus Theromyzon, it may be a duck leech, or at least a waterfowl leech. While it is thankfully uninterested in humans, it does have the rather uncomfortable-sounding habit of frequenting the nares (nostrils) of said birds, which makes it only slightly more agreeable. But, I found the Wikipedia article on one European species, T. tessulatum, rather intriguing, and it encouraged me at least to consider a little more empathy and respect for these hematophagous parasites, and perhaps investigate further:

 

"When parasitizing ducks and other waterfowl, T. tessulatum invades their mouths and respiratory passages. At other times, it is free-living in freshwater habitats. The adult broods its egg capsules on its under surface, where there may be as many as two hundred eggs. When the young are ready to emerge, the adult uses its sensilla organs to detect vibrations in the water and will move towards any disturbance that might be caused by a potential host. Suitable hosts are those with body temperatures of between 37 and 40 °C (99 and 104 °F). Although generally nocturnal and negatively phototactic (avoiding light), when the brooding adult is ready to release its young, it may swim in open water in the middle of the day. If it finds a suitable host, it attaches itself with its sucker to the nasal passages, the respiratory tract or inside the mouth. This leech is unique in that the adult attaches to the host but does not itself feed on it; instead, the young that it was brooding transfer to the host to take their first blood meal."

If you happen to own "Ecology and Classification of North American Freshwater Invertebrates", then you will have access to much more information than the Google Book result will give you about Theromyzon and other leech genera. I may have to borrow this book from the library, if for no other reason than to offer a cozy dinnertime or fireside reading of the leech section for my loving family.

Happy October!

Tanya

[Bill Gerth]

Hi Tanya,

I don't know what that leech is off the top of my head, but I am pretty good at keying out invertebrates and I have a key that should work. If you'd like me to try to ID those, I'd be happy to give it a go. Do your family members still have some live specimens or would they be willing to grab some more?

Just let me know if you'd like to hand some of those over...

Cheers,

Yours,

Bill

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[Tanya Lasswell]

Thank you, Bill! We would love to hand some over. 

Did they keep them? No. But, my 8-year-old said it would be easy enough to look out for again, but was not interested in using the aquarium net to search specifically for leeches. As the by-catch of small fish like the last time, though, that would be ok. We will head over there again sometime this week, I'd guess.

I'm always interested in knowing more, even if I am hopeless with a key myself! If you end up with an ID (before we find more and deliver them to you, of course), I use iNaturalist fairly frequently - the leech observation is here, along with other invertebrates I seem like photographing with a cell phone (and of course know next to nothing about).

Warmly,

Tanya

[Randy and Pamela Comeleo]

It is easiest to remove the leech off the top of your head before trying to identify it.  That way, you don't need mirrors.

Randy

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From: "Bill Gerth" <b_g...@comcast.net>
To: "Tanya Lasswell" <tanya.l...@gmail.com>, "mid-valley-nature" <mid-vall...@googlegroups.com>
Sent: Sunday, October 10, 2021 1:11:34 PM
Subject: Re: [MidValleyNature:6205] An October Willamette sanguivore

To view this discussion on the web visit https://groups.google.com/d/msgid/mid-valley-nature/1351834514.284818.1633896694491%40connect.xfinity.com.

[Bill Gerth]

Hahaha!

Thanks, Randy. 😉😅