Sand Dollars put out their gametes once a year when an environmental cue triggers them to start spawning. Once a few of them put out gametes, the others in the area will usually all start too. After several trials where we were unable to induce animals to release any usable eggs, it seems this behavior worked out poorly for us and that all of the animals we collected originally spawned out when we were not in the lab. So, more sand dollars were ordered from down east Maine (which is apparently Northern Maine).
When the animals arrived we were slightly nervous that the stress of being collected and shipped may have caused them to spawn or that they may have already spawned in the wild. These fears were quickly eliminated though. As we unpacked the animals and placed them into tanks, 20 out of the 26 we received immediately started spawning. So many potential gametes to be used for experiments were floating right there in front of me, just taunting me and almost causing a panic attack. There were orders of magnitude more eggs than would be necessary to conduct my entire project, but unfortunately we did not have the time or space to use hardly any of them and the eggs go bad a few hours after they are released. We were able to isolate several animals and set up an experiment that went extremely well, but because the animals spawned at a time that we would not have picked, we had to stay in the lab until 2:30 in the morning checking on the results. We also were able to stop some of the females from putting out all of their eggs by putting them in the fridge.
It seems we either get no data or so much at once we can’t use it all. We did get some very exciting data but we may have trouble conducting more spawnings with the animals we just received. We already tried to spawn some of the ones that we had put in the refrigerator but things did not go as well as hoped. They did still have eggs when we induced spawning, but the eggs wouldn’t fertilize well so more will have to be ordered more for future trials. I really like working with sand dollars and echinoderms, but sometimes it can be frustrating. I wish they would just do what I want them to. I think we will be able to have more success before the end of the summer though and we got some encouraging data last week, so I’m still in good spirits. Can’t wait to get more animals next week! This time we will be more prepared for the possibility of a giant spawning event upon their arrival.