Ocean STEMulation: Whale Falls



Focusing on science, technology, engineering, and math (STEM), as they pertain to the ocean.

This year, for the very first time, scientists documented a whale fall in Antarctic waters, almost a mile below the surface. The skeletal remains of this southern Minke whale have been the source for the discovery of at least nine new species. This discovery is also providing insight into ocean processes such as larval dispersal between remote habitats and ocean nutrient cycling.
 

What is a whale fall? After a whale dies, its body may float away and wash up onshore somewhere. But other times, the carcass falls to the seafloor and sparks an oasis for life with the energy it delivers.

The deep abyssal plains–vast flat expanses of deep seafloor – are environments that are very low in nutrients. This habitat is known to be home to an amazingly diverse array of microbes, but it can’t support very much in the way of larger life forms. A carcass, however, delivers a big dose of nutrients to the system.


Photo by NOAA's Undersea Research Program via Wikimedia Commons, Public Domain. 

In the perfect example of the circle of life, a whale’s decomposing body, known as a whale fall, becomes its own specialized seafloor habitat. It can support an entire community of incredible animals - sometimes even for decades. 

A whale fall community attracts an array of deep sea animals, and the species patterns changes over time. During the first two years or so, scavengers consume the flesh – the species that show up vary depending on how deep the whale fall is but they can include critters such as hagfish, crabs, rattail fish, and sharks.


Photo by Craig Smith NOAA via Wikimedia Commons, Public Domain.

The following two years, the bones and surrounding sediments are colonized by animals that consume leftover tissues. The final stage can last a long time – perhaps even a century – while sulphur-loving bacteria break down what’s left of the whale fall.

One of the specialized animals that colonizes the bones and break them down is a worm called Osedax, or the zombie worm. Similar to the worms found around hydrothermal vents, Osedax worms have no stomach or mouth; instead they feed on the bone with the help of symbiotic bacteria.


Watch this stunningly artistic video “Whale Fall (after life of a whale),” to learn more about the stages of a whale fall community.


Whale falls have been documented in various locations and they are thought to be much more common than we now know because they are difficult to locate with current technology. Most research on them has been done with whale remains intentionally sunken by scientists.

In this video, captured by a submersible in Monterey Canyon off of the California coast, you can see a real whale fall that was created by researchers and is providing insights into this phenomenon.

In the video below, you can see footage taken by a submersible of a whale fall in Monterey Canyon off of the California coast.

Whale fall research provides insights into how the ocean recycles nutrients. It also provides clues about how remote specialized habitats, such as hydrothermal vents, are connected. It is possible that some species that are specialized to hydrothermal vents can also be found on whale falls. Such species are thought to spread as larvae drifting in the currents looking for these specific areas to settle. However, precisely how they can settle, colonize, spread, and resettle is still a great mystery!

 

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