Plants have much lower levels of fats than animals do. Why is this?

Plants have much lower levels of fats than animals do. Why is this?

Plants are generally not placed at a disadvantage in using starch as a principal energy storage
macromolecule, because of their sedentary lifestyle. In situations where efficient (and therefore lightweight)
storage of calories is advantageous in plants, triglycerides may be found. Seeds, which must store a maximum
of calories in a limited space, are often rich in fats and oils. Oil-rich seeds, such as those from the cotton
plant, are valuable commercial sources of oil.
Animals, because of their increased locomotion relative to plants, benefit from lighter-weight sources
of energy and, hence, have evolved mechanisms to produce and store higher levels of fats than plants do.
An illustration of the importance of fat storage in advanced vertebrate animal forms is their gradual
development of a special organ, the adipose tissue mass. Among fish, fat is stored in an irregular fashion
within muscle. Amphibians possess fat bodies, and reptiles have a rudimentary adipose organ. In birds
and mammals, however, a metabolically competent adipose organ exists that is not merely a storage depot
for lipid but is actively involved in the synthesis of lipid from carbohydrate. In mammals, the fat tissue is
exquisitely sensitive to a variety of hormones and may even be used diagnostically to test for the activity
of such hormones. Insulin, the major hormonal influence in the conversion of carbohydrate to fat, is
assayed by measuring its effect on the uptake of glucose by adipose tissue.