SAMi and Truman help make cast for spider crab at Point Defiance Zoo
Spider crab

In May of 2021 Yuki, one of the large Spider Crabs at Point Defiance Zoo and Aquarium (PDZA), started to molt.  As the crab molted, it got stuck, something felt funny, so it dropped a limb! Spider Crabs drop limbs as a survival and protection mechanism. 

3D scan of a crab dactyl

3D scan of a crab dactyl

First fitting of the crab cast

First fitting of the cast

Yuki dropped a few limbs and one of their walking legs was bent. Due to the bent walking leg, PDZA staff applied a flexible plastic to help brace and take pressure off that leg. Another side effect was that the crab started to place more pressure on his chelae. With the chelae getting worn down, the PDZA staff had to come up with some alternative to keep this from getting worse.  The PDZA staff continually monitored the crab and started brainstorming treatment plans.  Mark Murray, a PDZA Aquarist, mentioned this to Matt Lonsdale, a SAMi Fisheries, Marine Bio, and AP Bio Teacher. Ideas flew as the two worked together to come up with a solution. 

A short while later Mark, Matt and Martin Splinter’s Truman MS Robotics Club collaborated to 3D scan the crab’s dactyl. The resulting scan was shared with Troy Hashagen, SAMI’s Computer Science teacher. Troy worked with students in his Adventures and Applications class to digitally design and then 3D print a cast.

Further steps in the iterative process for the crab's cast

Further steps in the iterative process for the cast

When the right time came in the treatment cycle, Mark and the team attached the cast.  It worked but could be improved leading to feedback. Troy worked to modify and resize the design, leading to a design cycle with multiple iterations.

SAMi and Truman are grateful for this opportunity to collaborate and help students see the application of their learning.  SAMI, Truman MS and PDZA continue to build opportunities for students and staff to work together.