Into the deep!
When I left last we one more site to sample from, which was done at night with the help of flood lights on the deck. Once again the bongo and neuston nets were deployed. This last stop of the night stood out from the others since we deployed a bongo net this time reaching a depth of 500 meters. This sample was taken in the middle of the mesopelagic zone which spans vertically from 200 to 1000 meters. This zone is sometimes referred to as the “twilight zone”, because some light still penetrates. Fellow Floridian, Kendall Lord, has been a big help identifying the deeper living fish. He is graduate student and research assistant at Nova Southeastern University. He works with Dr. Tracey Sutton, his advisor and the DEEPEND Consortium Director. Kendall is working on his Masters degree in Marine Science. His thesis will cover the history of research in the bathypelagic zone (> 1000 meters below the surface). He’s using research starting with the 1870’s with reports from the HMS Challenger all the way up to the Census of Marine Life from 2000-2010.
One of the first organisms pulled out was a purple jellyfish that Kendall informed me was a Periphylla periphylla, the helmet jellyfish.
We also found a bristlemouth fish (Cyclothone sp.), the most abundant vertebrate on Earth! Some of these little guys are serial hermaphrodites, specifically protandrous, meaning they are males first and then turn into females. Clownfish change their sex in the same way.
Many of the zooplankton collected were either clear, red, or black. This is part of their camouflage to help them hide from predators. The red shrimp pictured below stands out amongst the other organisms on deck, seemingly a contradiction. The reason some organisms in the deep are red in color is because it doesn’t penetrate as deeply as the other colors. Those bright red shrimp actually appear black in the mesopelagic zone where we are sampling. The clear organism that you can see only part of in the picture above is a larval eel, or leptocephali.
Perhaps the most exciting organism collected was a heteropod. In hand it appeared to be a gelatinous blob. When placed into a small tank for observation we were able to observe the mollusk’s unique swimming behavior that earns it the nickname “sea butterfly”. You can see video here. This unique gastropod is quite the predator! We later witnessed it feeding on the eel larvae which was easily 10 times its size.
After collecting the samples we went into one of the labs to take pictures and sort the organisms into Whirl-Paks. The fish in the picture below is a hatchetfish.
We began again this morning around 6:30 am. The weather is fully cooperating and the plan is to get through 12 sampling sites today.