Marilia sp.

Mark Melton

Active Member
These are from the Russian River in California. They are found in clean areas of sand interspersed with large cobble. Larvae are found in the sand burrowing around and on the cobbles as pupae. They range in size from 5 mm-11 mm in length as larvae and 7-11 mm as pupae.

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Larvae and case

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Empty larval cases

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Larvae inside case



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Pupal cases

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Pupae

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Pupae


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Pupae


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Pupae

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Empty pupal cases

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Full pupal cases


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Pupae gotten from cases above
 

cabezon

Sculpin Enterprises
WFF Supporter
There are very interesting changes in grain size along the length of the larval cases in those first few photographs (and far less so for the pupal). I wonder if the grain size changes as the larvae grow. That is, most of the larval cases reflect long-term residence. Or, the change in grain size, from finer to coarser, reflects a habitat shift from calmer, lower-current locations dominated by finer sediments to higher-velocity locations with coarser sediments. In the first picture, the habitat shift was dramatic, but in others, the change in grain size (and presumably habitat) was more gradual.
Steve
 

Mark Melton

Active Member
I think that the grain size changes as the larvae grow. They seem to stay in the same area as they get older. Remember they seem to burrow into the sandy areas and these are few and far apart. Also they are most abundant during times when the water doesn't reach anything approaching flood stage. As far as the pupal cases are concerned possibly the posterior end wears away or breaks off as the larva grow.
 

Zak

WFF Supporter
That's so cool. Great photos! I'm not sure nature's art can be improved upon, but this guy is trying:

 

Mark Melton

Active Member
That's so cool. Great photos! I'm not sure nature's art can be improved upon, but this guy is trying:

Yeah, I saw that article before. Pretty cool what he came up with. Like you I'm not sure nature's art can be improved on, but it can be modified and made more expensive.
 
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