Whale carcasses provide food source for years | Polarjournal
A dead baleen whale at a depth of over 1,000 meters – a feast for scavengers in the deep sea. (Photo: OET/NOAA)

There are few animals that trigger such strong emotions as whales. Whales inspire – but whales also stir up emotions when it comes to whaling. Also, there are news and images of stranded whales, which most likely stray from their path due to environmental influences and noise. Whales can also live well over 100 years, depending on the species.

But hardly anyone thinks about what happens to a whale after its death. The vast majority of whales die in the open ocean, unnoticed by humans. Following their demise, the animals sink to the bottom of the sea. Their life ends, but their carcasses provide a valuable source of food for numerous other animals and microorganisms. Indeed, the death of whales is likely to be an important evolutionary factor in the ocean. Moreover, in Australia and other countries, stranded whales are dragged into deep water to decompose.

Whale fall in the Monterey Bay National Marine Sanctuary, a marine protected area in California. At a depth of 3,240 meters, octopuses and other marine life swarm around the sunken carcass. (Photo: OET/NOAA)

A dead whale sinks in free fall, often several thousand meters into the depths of the ocean until it finally arrives at the bottom. The phenomenon is called whale fall. However, it doesn’t take long before it gets company. Small and large fish, octopuses and other marine organisms start feasting on its carcass.

In the nutrient-poor waters of the deep sea, each whale fall provides a packed wealth of nutrients and serves as a food supply for numerous life forms.

The remains of whales and other marine organisms are an important food source for a large number of scavengers. How long it takes the animals to decompose a whale carcass weighing up to more than 100 tons is still unclear. What is for sure is that the table is richly set for the assembled scavengers for a long time.

Whale carcass at Davidson Seamount at a depth of 3’240 meters

In general, people rarely get to see a whale fall. In those depths, water pressure is very high and there is complete darkness. A good example of what happens after a whale dies is shown by footage from the October 2018 NAUTILUS expedition using a remotely operated underwater vehicle (ROV).

The U.S. researchers on the expedition were truly excited when a whale skeleton four to five meters long appeared in the spotlight cone of their submarine. The skeletal remains of the whale lying on its back are estimated to be 4 to 5 meters long.

Surrounding it were plenty of scavengers. The video shows eelpouts, squid and polychaetes, like the bone-eating Osedax worms. Overall, the video showed a high diversity of species for such depths and, even more exciting, a high density of organisms. This demonstrated to the research team that such carcasses form real oases.

Close-up of the whale fall which has been visited repeatedly with cameras by scientists from “Ocean Networks Canada” since 2009. (Photo: ONC)

Whale carcass – food source for years

The latest visit by Ocean Networks Canada researchers to a whale about 16 meters long that has not yet been specifically identified shows that it continues to provide food and habitat for fish, crabs and snails 14 years after its discovery. Specifically, the researchers were able to detect, among other things, granadier fish, which belong to the cod family, giant isopods and so-called tube worms. The latter have nested on the left jawbone of the whale and have been shown to live there since 2009.

Heiner Kubny, PolarJournal

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