Crab Spider Season!

Salmon

Arachnopeon
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Mar 25, 2017
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With April flowers blooming... I've been seeing a lot of crab spiders sitting waiting for small pollinators on large flowers. So far I've seen white and yellow varieties (sp. unknown, possibly genus Misumena) and I've been wondering... are there biotypes of crab spiders adapted to specific flower species from state to state? I know pink spiders and green spiders occur in some species, but are there crab spiders for nearly every color of flower in their native range?
 

MetalMan2004

Arachnodemon
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My uneducated guess is yes to those questions. I have no clue though. I've seen a couple of crab spiders lately as well.
 

RTTB

Arachnoprince
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I am not a spider expert but I think they are crab spiders I see on the Oleander blooms at my house. The spiders take on that pinkish reddish color matching the flower/bloom.
 

Salmon

Arachnopeon
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Crab spiders can actually change color:

https://www.wired.com/2009/11/spider-color-changing-mystery/

However, that same article, interestingly, noted that t.here was no change in capture efficiency between spiders whose color matched the flower they were on vs. those which did not.
that's incredible! I had been wondering if that was the case. That's very strange though... I wonder why the color doesn't seem to matter?

Edit: the article goes on to say that the color is more about hiding from predators than prey, so it might have something to do with ultraviolet patterns on flowers that only pollinators can see.
 

schmiggle

Arachnoprince
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I thought the article said that it didn't help much with predator camouflage either...

I think this will remain a mystery for a while.
 

Salmonsaladsandwich

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The article said there was only one instance of a bird eating a spider. That's not exactly a large data set. Even if he didn't see spiders instantly being devoured when moved to a flower of the wrong color, I find it highly doubtful that camouflage makes no difference in spider survival. It doesn't "shatter the myth of crypsis by color in crab spiders", it merely shows that crab spider camouflage is a passive predator- avoidance adaptation rather than an aggressive prey deception ploy.

And the article doesn't mention other factors that could come into play. Goldenrod spiders don't always sit on top of flowers- sometimes, they hide underneath them instead and lunge at prey from below. Individuals that are sitting in top of flowers sometimes scurry out of sight when approached. Was there any difference in the behavior of spiders transferred to flowers of the wrong color?
 

schmiggle

Arachnoprince
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The article said there was only one instance of a bird eating a spider. That's not exactly a large data set. Even if he didn't see spiders instantly being devoured when moved to a flower of the wrong color, I find it highly doubtful that camouflage makes no difference in spider survival. It doesn't "shatter the myth of crypsis by color in crab spiders", it merely shows that crab spider camouflage is a passive predator- avoidance adaptation rather than an aggressive prey deception ploy.
I think the whole point was that there was little predation either way. However, you do make a good point that their major predators might not be birds at all.
 

Salmonsaladsandwich

Arachnobaron
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I think the whole point was that there was little predation either way. However, you do make a good point that their major predators might not be birds at all.
As far as we know, predation wasn't observed because the researcher's presence was scaring birds or other predators away.

I do know that one major predator of goldenrod spiders is mud dauber wasps. Their nests are often full of them.
 

Salmon

Arachnopeon
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It is definitely doubtful that a spider that is the exact same color as a flower would be so for no reason. Have there been any studies on how they change color? Is it similar to cephelopods? I can't think of any arthropod that changes color in a similar way off the top of my head.
 

schmiggle

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Umbers et al. 2014, a paper about color change across arthropoda, says that the mechanism in misumena involves oxidizing or reducing a cuticle pigment--I think the oxidized color is yellow. Other species have different mechanisms, but there is a wide range of arthropod species that change color. It's particularly common among crab spiders and orb weavers, it seems, at least with regards to arachnids.

Either oxidation or reduction of pigments has to be energy intensive, and possibly both are. In addition, color change can take up to 25 days. I will eat my hat if there's no adaptive mechanism behind it. However, that paper also noted that the evidence for crypsis in crab spiders is equivocal at best--the color change in misumena makes no difference in their conspicuousness to birds and bees, because both groups see in the UV spectrum. They also note that certain crab spiders actually change to become more conspicuous, which allows them to lure prey. So I suspect there is a complex adaptive significance to this color change.
 

Salmon

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Umbers et al. 2014, a paper about color change across arthropoda, says that the mechanism in misumena involves oxidizing or reducing a cuticle pigment--I think the oxidized color is yellow. Other species have different mechanisms, but there is a wide range of arthropod species that change color. It's particularly common among crab spiders and orb weavers, it seems, at least with regards to arachnids.

Either oxidation or reduction of pigments has to be energy intensive, and possibly both are. In addition, color change can take up to 25 days. I will eat my hat if there's no adaptive mechanism behind it. However, that paper also noted that the evidence for crypsis in crab spiders is equivocal at best--the color change in misumena makes no difference in their conspicuousness to birds and bees, because both groups see in the UV spectrum. They also note that certain crab spiders actually change to become more conspicuous, which allows them to lure prey. So I suspect there is a complex adaptive significance to this color change.
Oh I'd love to see the color change on an orb weaver. They usually come in such spectacular patterns.
 

The Snark

Dumpster Fire of the Gods
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Hasn't anyone else cruised the rose gardens as a kid, looking for crab spiders? Find it on one color rose and relocate it to a different color rose. Over a period of a few days they change color.
 

Ratmosphere

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One time I was skateboarding and a flower crab spider landed on my head. I grabbed it off and it just looked at me. I think it was a Misumenoides formosipes.
 

Salmon

Arachnopeon
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Hasn't anyone else cruised the rose gardens as a kid, looking for crab spiders? Find it on one color rose and relocate it to a different color rose. Over a period of a few days they change color.
That sounds like a really fun lab experiment to do with students...
 
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