Bioluminescence Cruise: Vertical Migration: Blog 3

Hello my name is Richard Hartland, I have spent many years traveling around this amazing planet we all call home. I fell in love with nature as a small boy in Scotland and I decided to spend the rest of my life trying to learn all I could to hopefully help us understand our place in this world and what makes it tick.

I am currently a graduate student in Dr. Tammy Frank's deep-sea biology lab at Nova Southeastern University, Fort Lauderdale. Here I am studying the assemblage of Sergestid shrimps in the Gulf of Mexico so that we can better know them.

I want to tell you about a pretty simple concept to understand called vertical migration. When an animal, crustacean, fish or other, moves either up or down in a column of water for a "purpose" and then returns to its prior depth we call this vertical migration. The most common form is diel vertical migration and this occurs when day turns to night and vice versa over a 24 hour period. Animals typically migrate into shallower waters at night and then go back to the depths of the ocean during the day. They can migrate hundreds and hundreds of feet each night.

Any size animal can be a vertical migrator, from the smallest to the largest creatures in the ocean. The distances they migrate can vary wildly between these different species, however their reasons for doing so are often similar. They more common reasons to perform this migration are as follows. Feeding is often performed in the warmer, shallower waters and then the animal's retreat to the cooler deeper waters where they can digest their meals more effectively. Predator avoidance is much easy at nighttime in these shallower waters as there is no light from the sun to give away that they are there. Sunlight itself can be harmful to these creatures and so when it is dark they are able to patrol the surface waters without fear of damage from ultraviolet light. Finally, these animals can use the strong surface currents to help disperse their young to aid the spreading of a species to prevent them over exploiting an area.

I have provided some pictures of vertical migrating shrimp below...Enjoy!

Pictures include examples of mid-water, mesopelagic shrimp from the family Oplophoridae

Photos provided by TYChan