Many of our group are self-described fish geeks and use this taxa group in our modeling research. So we've decided to force our love of fishes onto the readers of this blog with a weekly value-added segment known as Fish Fridays!  Fish are a fantastically interesting and large group that include many classes of organisms, and it was pointed out to me by Dan just last week that for fishes to be a monophyletic group, humans would be fishes as well! So we should have plenty to talk about. This segment is intended to provide brief and fun natural history stories about all things fishy, and so it might not always deal with species in space themes.

For this first Fish Friday, I've decided to geek-out on a relationship between freshwater fish and mussels that I've been thinking about a lot lately. It's a bit of a focus on mussels instead of fish, but it's just such a cool relationship and story of fish mimicry that I couldn't resist. 

As we study freshwater fishes, we have to constantly adapt research approaches to incorporate the distributional constraints that a river network places on these organisms, and with this in mind, we might as well be working with freshwater mussels as their ecology and distributions are fundamentally tied to fishes. This stems from the reproductive ecology of freshwater mussels.

In freshwater, female mussels produce eggs that develop into a larval stage called a glochidium, which temporarily parasitize fish, attaching themselves to the fish's fins or gills. In some species, release occurs when a fish attempts to attack the mussel's minnow or other mantle flaps shaped like prey; an cool example of mimicry. 

Mussel larva, glochidia, are generally known to be species-specific and will attach to any fish gill, but only live if they find the correct fish host. Though from what I gather there is still a ton not known about specific mussel-host relationships.  The glochidia, once attached to the correct host's gills, will live there for a number of weeks before breaking free and dropping to begin an independent and sessil life. This reproductive ecology of mussels tie them directly to the distribution patterns of their host fish, and thus research in distribution of fishes lends well to studying mussels.  I leave you with a video that explains this all using largemouth bass and the genus of Lampsilis mussels.  I think the one featured in the video is a pocketbook mussel, thought I'm not sure.

Ben Labay is a "fish-geek" and research associate for the Texas Natural History Collections at UT Austin

See his fish art at: www.inkedanimal.com