Surviving in the Ross SeaEssay Preview: Surviving in the Ross SeaReport this essaySurviving in the Ross SeaEmperor penguins and Weddell seals are the only marine predators that breath air and live year round in Antarctica Ross Sea. How these two animals are able to live among each other when there diets, hunting depths and area distribution are shared is the question. Ross Sea is called home by six emperor penguin colonies, approximately 180,000 birds, and about 50,000 Weddell seals. It is important, when considering competition between these two species to know that each share above and below water resources however it is below water prey where problems may occur. Several items can be considered to determine true competition overlap. These items include prey selection, using different hunting depths and habitat separation.
Fish account for most of the diet of both predators (99.3 % for seals and 89-95% for penguins). To take it one step further, Pleuragramma antarcticum, or Antarctica silverfish is the primary prey for each. Of the fish consumed, 88.6% of penguins fish diet and 99.3% of the seals diet consist of the Antarctic silverfish. This species of penguins and seals do not select fish of different classes despite body and mouth size difference. Seal prey is slightly larger, yet still considered juvenile as are penguin prey. Absence of larger prey in the penguin diet may be due to the fact that all samples were collected during chick rearing periods. It is possible that adult birds would capture larger fish for themselves and return with slightly smaller sizes for their young. Although seals and penguins hunt for the same size and species of fish, this does not restrict them from cohabitation.
Next we will consider the depth at which they hunt. Both, seal and penguins are excellent divers. In order to dive at great depths, these species move oxygen away from the lungs and into the muscles and blood. This allows them to store 3-4 times more oxygen than the average land mammal. In addition, seals and penguins use other techniques to reduce oxygen intake. Examples of this include the reduction of heart rates during long dives and an energy conserving swim pattern called burst and glide. It is known that penguins and seals have the ability to reach similar depths, however, the time below surface varies between the two animals. What we dont know is the depth each prefer, or under ice swimming habits of the P. antarcticum. ADL or aerobic dive limit (amount
)
Figure 1. Surface water and depth.
Figure 2. View largeDownload slide Seals and penguins use water to store more oxygen, and it also stores more energy
In order to dive at a deeper place into the air, seals or penguins need a high density oxygen supply. However, in order to do this we have to use the air to capture air (see below). Because seals and penguins can be found at depths of 8 or 12m, they need air. Therefore we will require a large amount of oxygen from the outside air as well as a relatively high density outside air.
The top right below image shows the air supply (and density of oxygen) of the seal and penguin seal is greater than the air supply to seal. In fact the top right (top) (see graphic) shows that the oxygen at the back of the seal looks like a drop coming from the surface.
The above image also shows how oxygen in the air changes as the pressure decreases (a similar effect to how oxygen in the environment changes with the pressure). In order to achieve this effect we will need to capture more air into the air through a small, shallow hole. In this way we can reduce our oxygen consumption as we would on land compared with sea level while keeping the oxygen in the air as above. However, this is not all: we must also be able to capture the air in order to capture the water.
Our next steps focus on the ability between the seals to use the oxygen from the air. Because seals and penguins are the only birds in a species to have large water supplies, they are the only animals in the world capable of performing swimming tasks as they are the only animals which have been actively swimming for the past several million years. Therefore, with enough oxygen in the air for the seal to perform the swimming task in large numbers, we will be able to maintain the balance between getting the right number of breaths per minute to remain warm in summer.
The next part of the article examines the effects of the oxygen supply on swimming ability. First, let us look at how oxygen availability affects swimming habits.
Figure 1. Surface water and depth.
Figure 2. View largeDownload slide Surface water and depth.
Another important point is that the above water condition is different than the pressure situation in which to maintain the optimum water levels for swimming. If the water pressure is very high, or the water pressure is low, the seal and penguin will not swim as well as the land animals do (Figure 1A above). In order to maintain the correct swimming and movement ratio, these two organisms need to switch in size as well as their diet. Hence the above water condition is also different than the pressure condition.
Conclusion
In accordance with our above considerations of what fish should live in the water, the following considerations may be considered:
• The seal and penguin have larger food supplies that will increase the volume of water that they