III. The Central Question
The central question then is, "What adaptations permit life in the deep sea?".
The basic question has two parts. There are certain adaptive characteristics
of organisms that we can refer to as tolerance adaptations. These are adaptations that give organisms a toe-hold in a particular habitat. We can find these
sorts of adaptations in terrestrial, fresh water, and marine organisms.
In the deep sea, we find that there are a number of characteristics of animals
and bacteria--obviously there are no plants--that allow them to deal with
the different stresses that I mentioned a few moments ago: the pressure,
the extremes of temperature and the low levels of oxygen. These are tolerance
adaptations that give the organisms resistance to the hostile nature of
the environment.
Now, another type of adaptation is what is termed a capacity adaptation.
These adaptations refer to differences in species that set the right rates
of activity for their environment. Again, this is a type of adaptation that
we can find in all sorts of environments. In the deep sea, we'll find that
the rates of life, whether this means locomotory activity, rates of growth,
whatever, are going to be strongly influenced by the nature of the food
supply, the darkness and the low levels of oxygen.
I would like to start by looking at tolerance adaptations to see what allows
organisms to withstand some of the physical conditions of the deep sea.
Then, I will look at how the rates of activity of the deep sea are adjusted
according to the biological, physical, and chemical characteristics of the
environment.
Now, in our laboratory, above a spectrophotometer where we do our high
pressure enzyme work, is this sign that a former student, Paul Yancey, made.
If there were road signs in the deep sea, you would see this sign because
it's indicative of the fact that as you move downwards in the water column,
pressure rises by one atmosphere for each 10 meters increase in depth and
begins to impose severe problems for organisms.
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