While doing field work yesterday (12 December 2020), we spotted some bright blue isopods in the intertidal zone. Although quite small (only ~2-3 mm long), their bright coloration really made them stand out against the reddish-brown rocks:
We didn't have a lot of time, but we took a few photos for the record:
We think this is Dynamenella sheareri, but we are keen to learn more about them, so let us know if you've seen blue isopods like this in your area!
5 comments:
They are beautiful!!
Terrestrial isopods fall prey to a virus that turns them blue/purple. I used to play with all the weeds and “bugs” in my urban yard, and the beautiful purple pillbugs were one of my childhood favorites. Many years later, as a TA for a course at BML (!), I met Ted Groscholtz (sp?), a grad student studying the terrestrial isopods. I asked him about the purple ones, and he told me about the virus. I wonder if that’s what’s going on with these marine isopods?
Hi, Marni!
Yes, we've been wondering about this a bit. Although I'm familiar with the terrestrial isopod story, it doesn't sound like iridoviruses have been seen that often in marine isopods. We just e-mailed Ted (Grosholz) last night to ask a few questions about the virus.
We had wondered if this could be a blue color form, as isopod coloration can be so variable. However, the iridovirus is an interesting possibility. It would be great if someone could confirm either way!
:) Jackie
P.S. There are some purple isopods under a log in this blog post:
https://bodegahead.blogspot.com/2020/03/at-home-under-log.html
These are identical to the ones I found in Washington back in 2002. If Niel Bruce's comment about color variability applied to this species I think it would be more common. Since that first occurrence I've looked for more populations with this coloration and yours is the second report in 18 years.
Hi, Leslie!
Thanks for your thoughts. I agree that the blue coloration seems more likely related to an iridovirus than color variability. There are enough people looking at isopods that you'd think more of these striking blue individuals would have been reported over the years if it was just a color morph. If it is an iridovirus, I wonder what causes an "outbreak"? I think we'll try to return to the site to get a better feel for how many blue individuals there are, but I was impressed with the number even from just a casual observation as we walked by while conducting other work.
Jackie
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