An adult petrale sole, a type of flat fish!
Hey guys! As part of my work at the NOAA lab and my masters program at CSU-Monterey Bay, I am looking at petrale sole, a right eyed flatfish that is common along the west coast of the United States from Baja California to the Bering Sea. My research involves trying to determine this fish’s fecundity, something biologists look at when trying to determine how healthy and abundant the offspring are from a species. In order to do this, we spend a lot of time looking at ovaries, the organs where eggs develop in a female fish.
While looking at some of my petrale ovaries, I came across something I hadn’t seen before. I noticed a small spiral looking thing at the very top of the ovary that resembled a worm. I asked my mentor on the project, Lyndsey, what it was. She explained that it was a NEMATODE! Nematodes are a type of round worm that can be found in all sorts of organisms. In fish, it is not uncommon to see these worms (sometimes more than 1!) attached to the ovary. Nematodes are parasites, which means they are getting nutrients from the organism they are attached to, which is called their host organism. The parasite usually has a negative effect on the host, either through making it sick or weak. Round worms are the most numerous multicellular organism on earth, and can live in a variety of different habitats.

Although the nematode was fairly small (about the size of a ladybug!), I couldn’t capture the whole thing under my foldscope. I did manage to see some pretty awesome views of the circular nature of the worm. Check out what I saw below!
The outside of the round worm.
More rings on the roundworm.
Round and round we go!
Maybe part of the head/mouth?
Nematode Parasite!