They dont release any oil
they "preen" their feathers with their beaks not put oil on them
Density is a derived unit because it's not reported as a pure unit. (A pure unit would be something like kilograms or meters.) In contrast, the units for density are kg/m3. Density is the ratio of mass to volume; mass has the unit 'kilograms' (kg) and the unit for volume is cubic meters (m3).
Density is an intensive property, which means the amount of the material is irrelevant. The density of a substance is constant.
Living things has emerged into three domains called Archaea, bacteria, and eukaryotes. Evident that support the idea that multi cellular that is eukaryotic cell evolved from the prokaryotic cell are the descendents of the separate prokaryotic cells that together form a union which are inter dependent.
For example: The mitochondria which is referred to the energy source of the cell is considered as the great-great-great-granddaughter of a bacterium cell which is free living. This free living bacterium bacterial cell was consumed by an other cell and this remained as the stable guest in the cell. This mitochondria provided chemical energy to the cell and also protected the nutrient rich environment. which surrounds it. This process of one organism residing in the other organism completely is called endosymbiosis.
<span>A sperm cell has half of the chromosomes than other animal cells I think</span>
