The term is simply a convenient name for organic compounds that are hydrophobic (water-hating) and insoluble in water but soluble in organic solvents such as acetone, alcohol, chloroform, benzene and ether. Lipids have a greasy or oily consistency. Lipids are composed of C, H and O. However, they have relatively less oxygen in proportion to C and H than do carbohydrates. Oxygen atoms are characteristic of hydrophilic (water-loving) functional group so lipids with little oxygen are much less soluble in water than most carbohydrates. They serve as concentrated storage materials, as structural components of cell membrane and cell organelles.Thus, lipid in penguin's feet is too keep them warm in cold whether.