Identify the feature not unique to vertebrates.

a) vertebrae

b) backbone

c) skull

d) skeleton

Skeleton is the answer

Explanation:

Vertebrates have a skeleton made of bone and cartilage inside the body. Some invertebrates have an internal skeleton, but it is not made of bone.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c

. ph changes the ability of them he enzyme to dissolve in water.