Graduate student slaying the dragons at sea

Post by Ashley Marranzino

Hi everyone!

My name is Ashley Marranzino. I am an incoming PhD student working with Dr. Tracey Sutton. I am excited to be joining the fantastic team aboard the R/V Point Sur for my first DEEPEND cruise!

For this cruise I work predominately with “team fish” and help to weight, measure, and preserve every single fish specimen we collect after they have been identified. A range of scientists use the specimens we collect during DEEPEND cruises, so we make sure certain species are preserved appropriately for future analyses on topics like genetics, morphology, and diet.

Ashley Marranzino, April Cook, and Drew Mertzlufft process the fish specimens after every tow. Photo taken by Dr. Isabelle Romero

I am also in charge of recording all of the size and preservation information for each specimen in our database. This ensures that we can track everything we catch and that the specimens and data we collect at sea can be effectively used and dispersed to different scientists after the cruise.

After we finish sorting through and processing our catch, I have also been collecting data for my own research looking at the sensory biology and ecology of deep-sea dragonfishes.

The threadfin dragonfish, Echiostoma barbatum, is covered in bioluminescent organs called “photophores”. Image by Dr. Isabelle Romero.

Bioluminescent (light-producing) organs cover the head and body of these midwater predators. Scientists hypothesize that some of these organs are used to find food (like the elaborate chin barbels on many species that likely lure in prey) while others are used to camouflage the fish by producing light similar to that filtering through the waters above (called “countershading”). But we still do not know the function of other bioluminescent structures in dragonfishes. Since we cannot keep dragonfishes alive in aquaria or easily watch them in their natural environment, I am trying to infer the function of the bioluminescent organs by examining their structure and placement on the body.

Image by H Judkins

 I am excited to get back into the lab and continue examining some of the beautiful dragonfish specimens we have collected this trip!