The Ossicle Sorter and How to Digest Your Very Own Brittle Star Arms

"Ossicles" literally means "tiny bones" and is something of an understatement when it comes to brittle star skeletal matter. However, the ossicles of this bioluminescent marine organism may possess very novel refractive properties. In order to analyze this refractive potential, samples of three different types of ossicles of three different species of brittle stars must be collected. This is done by digesting brittle star arms.

How to Digest Your Very Own Brittle Star Arms

First, you take an Ophiopsila californica brittle star and soak it in anesthetic. Then you carefully cut off the arms at the edge of the body disc, making sure not to harm the main disc in the process so that the brittle star can fully recover (regrow all of its arms for further...removal). Then take the arms and chop them up into lots of pieces to create the a lot of surface area. Measure approximately .2 grams of arm for this recipe and put it in a medium-sized vial with a round tip. Then measure .025 grams of the flesh-digesting enzyme Protease (or .1% of solution) into a glass beaker and mix with 2.5 milliliters of Artificial Sea Water. [Warning: Protease does digest flesh and cannot tell the difference between different types of flesh and will most likely attempt to eat your flesh if given the chance....in short: wear gloves.]

After you've dissolved the Protease in ASW, pour into the vial with the cut-up arms, seal with a stopper and Parafilm just to be safe, shake it up a little, then attach the vial to a rotator and place in an oven at 26 to 28 degrees Celsius (it's not that hot). Let it rotate and digest for at least 8 hours. Make sure you check on it since the solution will get darker and darker as more flesh is digested. You can also put the vial under a light microscope to catch a glimpse of how clean the ossicles are, which should look like white powder when the arms are fully digested. When it is fully digested and the ossicles are as clean as they will get, let the mixture settle and drain the supernatant. Then carefully rinse with MilliQ (de-ionized) water several times to ensure all the Protease solution is gone, but make sure not to lose any ossicles. Once you have just the ossicles, put them into an Eppendorf tube (uncapped) and leave them to dry in an oven on high heat overnight.

From my lab notes

The quite beat-up rotator. The vials are attached by slipping them under the rubber bands.

A nice, big lab oven set at the level I usually put it at to achieve the ideal 26 to 28 degrees Celsius temperature.
(The red light to the right indicates it is heating.)

The thermometer thinks the temperature is approximately 26 degrees Celsius, or around 79 degrees Fahrenheit. 

Once they're dry, you're ready for the most fun part of the process: sorting the ossicles!