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The deep sea is an extremely hostile environment that covers 2/3 of the planet – there are extremely low temperatures, very high pressures, no light and very little food. This lack of food means there aren’t huge numbers of animals living in the deep sea, like those seen at coral reefs. Here is typical picture of the seafloor. However, occasionally large packages of food arrive on the deep-sea floor – like the bodies of whales, dolphins and large trees . These provide a huge input of food and also shelter for deep-sea animals. Animals rush to the carcass (some traveling great distances) causing a huge accumulation of life around the dead whale (whale fall) or tree (tree fall) that isn’t usually seen in the deep sea.

Whale falls, due to their enormous size, tend to go through several stages of decomposition. The first is known as the mobile-scavenger stage – this is when large animals, like sharks, rattail fish, hagfish, lobsters, crabs and amphipods, come to eat the flesh of the dead whale Here is a drawing of the mobile-scavenger stage. When the bones are mostly clean of flesh, the second stage begins: the enrichment-opportunist stage. A completely different set of fauna that are usually much smaller in size come to live off any pieces of flesh or poo left around the carcass – e.g, amphipods, snails, worms, isopods, small fish. Here is a photo of this stage from a whale fall found off California. The last stage is known as the sulphophilic stage. This stage can last up to 100 years (a long time!) and is extremely unique. Whale bones have huge amounts of fats and oils in them. Anaerobic bacteria use this fat releasing sulphides as a by-product. These sulphides form the basis of the food chain during this 3rd stage as different bacteria use these sulphides for energy. This is like plants getting energy from sunlight and forming the base of the food chain on land (photosynthesis); these bacteria use the sulphides for energy and form the basis of the food chain in this deep-water environment (chemosynthesis). The animals at the 3rd stage of the whale fall either have these chemosynthetic bacteria living within them (endosymbionts) or they feed directly on the bacteria growing on the bones. During this stage, the fauna is very specific – mussels, clams, isopods, amphipods etc. Here is a drawing of the 3rd stage stage.

These rare chemosynthetic ecosystems can live totally independent of sunlight. Up until about 40 years ago, scientists thought this was impossible! Other types of these ecosystems in the deep sea include cold seeps and hydrothermal vents. Here is a picture of some hydrothermal vents found in the Antarctic deep-sea at 1.5km depth. Do you see the huge abundance of life found at these special habitats when compared to the typical deep sea. Some scientists think that whale falls can provide stepping-stones for animals and their larvae to disperse the great distances on the seafloor between these hydrothermal vents as there are similar environmental conditions at both. This makes them very important to fauna in the deep sea.

One of the most interesting groups of animals found during the third stage of a whale fall, is known as Osedax (bone-eating) worm. The entire group was only discovered less than ten years ago! They are unique because they use roots to burrow down into the whale bones where they then release enzymes to get break down and eat the bone.

The deep sea is the last unexplored frontier on our planet – there is still so much left for us to discover – a lot of which may help the human race. For example: Because the deep sea is very cold and the animals which live there are accustomed, the bacteria found in the 3rd stage of the whale fall, which breakdown the fats in whale bones have been collected by scientists and are now used in washing powder which allows us to wash our clothes at cold temperatures to save energy in the fight against climate change.

A main part of my PhD project is I want to learn as much as I can about life living at these tree falls and whale falls, especially recording the different animals found in these habitats as they usually re not found anywhere else on earth. Every time anew food fall is found, there are species new to science on it. This shows how little is known about these habitats. It is thought that because many whale-fall fauna don’t live anywhere else, whaling may have led to the extinction of hundreds of these deep-sea animals as there are now less whale bodies for them to live on. This is another reason why it is important to survey what lives at whale falls and stop whaling! I also want to look at how the animals use these food resources and estimate how important they are to the entire deep-sea ecosystem. Here is a picture of me in the lab picking animals off some wood collected from 2km depth on the SouthWest Indian Ridge off South Africa!

There is no such thing as a typical day for me. Being a deep-sea biologist means that a large portion of my year is spent on ships like the RRS James Cook at sea. Because deep-sea biology takes place in water deeper than 500 m, humans cannot scuba dive there due to the high pressures. This means that at sea we use Remotely Operated Vehicles (ROVs) like this British ROV Isis to dive down into the deep sea and do our dirty work for us! These ROVs can send us live images and HD video, and also collect specimens, water samples and seafloor cores from the deep seafloor. On the ship, we work in 8 or 12-hour shifts to make sure the ship is constantly in use. We even work on Christmas Day! Going to sea is extremely tiring as samples need to be processed and preserved ASAP but fantastically exciting (unless you get really seasick!). My next expedition is to the Antarctic in December to look at some unique habitats like these hydrothermal vents and a whale fall.

When back on land at the Natural History Museum in London, I can usually be found in the molecular lab working on the DNA from the deep-sea animals collected at sea to determine if they are species new to science (which a lot of the time they are!). I also spend a lot of time at microscopes looking at small specimens and also at my desk, writing up all the results I get.

One of the strangest types of day that I can have is when a dead whale washes up on a UK beach. As this is where we get the majority of our whale bones for experiments, it means that we have to act quickly to get to the whale to cut it up before it is taken away. The last whale we cut up was a sperm whale which washed up in Kent and was filmed by the Channel 4 program ‘Inside Natures Giants”.  Here is a picture of the whale.