Week 2: Dungeness Crab in the Lab

Week 2 has ended and I have to say that Oregon is becoming more and more homely. Friends are being made and new experiences are occurring. Early in the week, core samples were taken in order to capture mud shrimp. A core sample, to those of you unaware of what that is, is where you take a large metal tube and press it completely into the ground and then proceed to dig all of the sediment out and sift through it while for mud shrimp. To get the core into the ground you must stand on top of it and do the “shrimp dance” which consists of wobbling motions. Once the mud shrimp were captured we measured the carapace length, sexed them, and checked for the infestation of parasites. The parasites are definitely not the most appealing creatures to look at, but they are still very interesting.

The mudflats show no mercy to those who science.

Mid-week many bucket lids were purchased (24 total). The reasoning for this is that we began to build experimental pit traps that would be size selective for the capture of small Dungeness crabs. We made two different designs, one with a larger whole and steeper funnel, and the other with a smaller hole and more gradual funneling. To set these traps, you basically just dig a hole in the ground and place the bucket in and wait for the crabs to fall in. Some people around here call them the “Dodos of the sea”. This is not due to having a resemblance with birds, but because of their ease of capture. After setting the traps we decided to place GoPro cameras onto two of the traps to capture some footage and observe the crab’s interactions with the traps. I’ve taken a brief look at the footage and there is some interesting behavior to note. I will definitely be including some of the video in my next blog entry. Several crabs were captured overnight, as well as a few Staghorn Sculpins, and a lone jellyfish. The next step will be to build 24 traps in total, and set them out in various locations. I’m really looking forward to see how things will play out with the implementation of our traps.

Young Dungeness crab captured in the pit traps

It’s been only two weeks and I already feel like I’ve learned quite a lot. Being from a freshwater background, marine and estuarine has offered a new perspective. 8 more weeks to go!

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2 thoughts on “Week 2: Dungeness Crab in the Lab

  1. You’ll get better at the shrimp dancing and mud walking!
    Do you have a picture of the traps so we can get a better sense of how they work? How did a jellyfish get in there?!

  2. Not much dancing when you’re waist-deep in mud! I’m glad to see that you’re developing a healthy respect for the intertidal mudflat habitat and it’s critters. Have you seen any other crab species? Are they easy to differentiate from Dungeness?

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