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Friendly/Terrifying Crayfish

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#1 Guest_EricaWieser_*

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Posted 26 August 2012 - 12:25 PM

I don't have much experience snorkeling in streams and rivers. Have any of you experienced a crayfish or shrimp crawling on you like at 2:40 in this video?

Is that common?

Right now my wading shoes are sandals with open tops and after watching this video I'm reconsidering that. Has anyone ever experienced a pinched toe from a crayfish? I haven't yet but maybe I've just been lucky so far and it's only a matter of time...

Edited by EricaWieser, 26 August 2012 - 12:27 PM.

#2 Michael Wolfe

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Posted 26 August 2012 - 01:51 PM

I dont read Japanese and didn't recognize most of the fish (I mean I saw the swordtail, but that's about it). But that guy looks looks like a Macrobrchium... a genus I have not encountered snorkeling.

But his actions almost remind me of satlwater cleaner shrimp, and I have had those come out and "clean" my hands when I was cleaning a saltwater aquarium.

And I have had a variety of minnows nibble on the hairs on my arms while snorkeling.

But I have never had a crayfish pinch me unless I picked him up... and never had one pinch my toes or legs at all.
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#3 Guest_FirstChAoS_*

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Posted 26 August 2012 - 02:24 PM

I never had a crayfish crawl over my foot but had a shrimp crawl over it in the ocean once. I do not touch crayfish as I am nervous of being pinched.

I wish the video focused more on the minnow and darter like fish, I am curious on what they are.

#4 Guest_centrarchid_*

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Posted 26 August 2012 - 03:27 PM

As a kid we had a livestock watering pond stocked with channel catfish and papershell crayfish Orconectes immunis. One year during drought (summer of 1989) catfish got restricted to a central pool in middle and crayfish had most of remaining area under water that was 6 inches or less deep. Crayfish numbered in the thousands and consumed anything you tossed in. One day when hot I got in laid quitely back in water. In just a few minutes I bet nearly 50 crayfish ranging in length from 2 to 4 inches where on me trying to bite through skin. They would grab hold with pinchers and attempt to bite with mandibles by placing their head right down on me. It was very unpleasant although it would have very difficult for them to break my skin. Skinny dipping would not have been tolerable at all.

#5 Guest_UncleWillie_*

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Posted 26 August 2012 - 03:54 PM

Never experienced that with crayfish, but I have with big freshwater shrimp (like the one in the video). In my experience, crayfish are more defensive, and shrimps tend to be more likely to 'explore'. I've had a large freshwater shrimps pick through arm and leg hair when I was in a small pool in the Seven Sisters waterfalls in Grenada. They were actually quite beautiful, deep blue and bright auburn accents. I know I have a pic floating around somewhere.

Edited by UncleWillie, 26 August 2012 - 03:55 PM.

#6 Guest_njJohn_*

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Posted 26 August 2012 - 03:58 PM

Looks like a long perch at :10.

#7 Guest_schambers_*

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Posted 26 August 2012 - 07:14 PM

A crayfish shouldn't bother you if you don't bother it. I like to fiddle around with them and they only bite or pinch me when I try to restrain them. Your mileage may vary, of course.

#8 Guest_gzeiger_*

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Posted 26 August 2012 - 07:56 PM

In my experience crayfish rarely pinch even when severely provoked.

#9 Guest_centrarchid_*

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Posted 26 August 2012 - 09:09 PM

You guys are not giving crayfish credit for what they will do when food is in short supply or they become habituated to your presence. I work with the little guys and generally they pinch only when on the defensive but when population density it high and food is limiting they become much more outgoing.

#10 Guest_Skipjack_*

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Posted 27 August 2012 - 10:02 AM

Yep! Erica, do not worry about the crays. They are much like snapping turtles, when in their element(water) they are docile. Only when you pull them out of water are they aggressive. Oh, and the pinch is not that bad anyway. If they turn up in your net, pick them up by the carapace, and you are safe. No big deal. Not much in freshwater that can actually harm you. Enjoy, and lose the fear.

#11 mattknepley

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Posted 27 August 2012 - 11:33 AM

I've never been pinched by a crayfish, unless I was seriously daring the crayfish to do it. I dared a lot of crayfish as a kid. #-o I'm much less arthropod-confrontational as an adult...
Matt Knepley
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#12 Guest_schambers_*

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Posted 27 August 2012 - 05:04 PM

I do remember when I learned that crayfish bite as well as pinch. I don't remember how I was holding it, but it couldn't get at me with its pincers when, CHOMP, it bit me. I was more offended than hurt, though, and I was totally provoking it. #-o

#13 Guest_centrarchid_*

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Posted 27 August 2012 - 06:23 PM

If you want to have crayfish actually bite you for the experience, then maintain them at high densities in a raceway where intermolt crayfish totally cover bottom several animals deep. Keep light levels low and water quality high. Stick one of your appendages in and wait a minute or two. Enjoy.

#14 Guest_dredcon_*

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Posted 27 August 2012 - 07:25 PM

I usually get them before they get me.

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#15 Guest_mywan_*

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Posted 28 August 2012 - 04:47 AM

Even as a kid I would try to get crayfish to pinch my finger on purpose. Even when get them to pinch they will not stay there long enough to even get a picture of it hanging from your finger. The last thing anybody needs to worry about is getting pinched, even in the unlikely event you can actually get one to pinch you.

#16 Guest_IsaacSzabo_*

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Posted 28 August 2012 - 06:29 AM

I have to disagree with mywan a little here. In my experience, at least some crayfish species have a reflex reaction to clamp down on anything they feel between their pincers when they are agitated. I certainly have had no problem getting them to clamp down and hang on to a small twig or other object, and I've seen it with fingers too. I saw one guy carelessly put his finger within the pincer of a large crayfish. The crayfish clamped down, and the guy had to fling it off with a lot of force. It cracked his fingernail and drew a little blood.

One thing to note is that crustaceans have slow-twitch muscles in their pincers, so they can clamp down and maintain that pressure indefinitely without using much energy. I've seen a woman get pinched on the hand by a blue crab. She could not get it off nor could anyone else by trying to pull the pincer open. Someone had to wedge an object between the pincer and use some leverage to finally loosen its grip.

I do certainly agree with mywan and others that there's absolutely no need to worry about getting pinched by crayfish when in the water. I've never seen them pinch unprovoked - only defensively when people were handling them. Also, I do think closed-toe water shoes are a good idea to protect your toes from the real dangers in the water - rocks and sticks.

#17 Guest_IsaacSzabo_*

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Posted 28 August 2012 - 08:51 AM

Also, the crayfish that broke my friends fingernail is a species with especially large and muscular pincers (Ringed Crayfish):

Posted Image

Crayfish with smaller pincers would not be able to do as much damage.

#18 Guest_centrarchid_*

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Posted 28 August 2012 - 09:13 AM

Ringed crayfish pinch harder than any of the species they are sympatric with. They seem to pinch really hard when water is cold. A medium sized ringed can cause more discomfort than even a large long pinchered crayfish.

#19 Guest_Usil_*

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Posted 28 August 2012 - 09:34 AM

I would say cleaning was his intention. I saw his little cleaner feet grabbing at particles on the skin just like thy do on rocks and wood.


#20 Guest_IsaacSzabo_*

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Posted 28 August 2012 - 10:50 AM

Ringed crayfish pinch harder than any of the species they are sympatric with. They seem to pinch really hard when water is cold. A medium sized ringed can cause more discomfort than even a large long pinchered crayfish.

That's interesting. This did occur in a coldwater spring. It makes sense to me that longpincereds cannot pinch as hard since their pincers, though long, are quite narrow and would not provide much leverage. Anyway, it sounds like my experience of the amount of damage a crayfish can do with its pincers is not typical for most species.

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