Some Animals Migrate Every Day. Here’s Why.

You’ve likely heard of seasonal migration, where certain animals move from one location to another depending on external factors like weather. However, did you know there’s a form of migration that occurs daily? Diel vertical migration (DVM), also triggered by environmental changes like temperature and light, is a common practice for many marine organisms. 

What Is Diel Vertical Migration?

Diel vertical migration is a daily, synchronized movement performed by certain marine organisms. These creatures include many zooplankton species, dinoflagellates, small fish, various shrimp, and jellyfish.

These animals typically migrate in an up-and-down pattern, hence the name “vertical” migration. They commonly move toward the water’s surface at night, then descend to deeper waters during the day.

According to an article published in the journal Global Biogeochemical Cycles, this form of daily movement helps organisms avoid predators, UV damage, and other threats, particularly during daylight. In fact, diel vertical migration is typically triggered by changes to light and temperature, as well as other environmental factors. 

Additionally, DVM helps organisms secure their food sources. At night, many migrate toward the water’s nutrient-rich surface to feed on algae. 

Pros of Diel Vertical Migration

DVM helps marine organisms achieve the following:

• Predator avoidance: As organisms retreat to deeper waters during the day, they may reduce their risk from visually hunting predators that are more active in well-lit, shallow waters.
• Food security: By migrating to the water’s nutrient-rich surface at night, organisms can access abundant food and nutrients.
• Protection from UV: As marine animals migrate away from the water’s surface and out of direct sunlight, they avoid harsh UV exposure, which could otherwise harm the organism and its DNA, sometimes even leading to death.
• Contribution to carbon sequestration: According to a paper published in the journal Biogeosciences, this daily migration helps transport organic carbon from the water’s surface to the deeper portions of the ocean. 
• Access to colder water: The National Oceanic and Atmospheric Administration notes that some organisms migrate to deeper, colder waters during the day in order to grow larger and produce more eggs.

Cons of Diel Vertical Migration

DVM is typically a beneficial practice for marine organisms. However, there can be some downsides, including:

• Predator run-ins: While marine organisms practice diel vertical migration to avoid predators, some will expose themselves to such threats during their daily movement. Many predators will capitalize on migrating prey and go in for the kill.
• Energy consumption: Diel vertical migration requires a significant amount of energy, which can exhaust the migrating organisms. This exhaustion might make it harder for them to search for food or escape predators.

Despite its few drawbacks, diel vertical migration is worth the risk for most marine organisms that practice it.