Along with the brown bear, it is one of only two of the eight modern bear species not considered globally threatened with extinction by the IUCN. American black bears often mark trees using their teeth and claws as a form of communication with other bears, a behavior common to many species of bears.
Planetary nebulae are astronomical objects made up primarily of gaseous materials. They are extended in size and fuzzy in appearance, and generally show some degree of symmetry. The nebula is illuminated by a central star, which sometimes is too faint to be seen.
Planetary nebulae are not related to planets, other than that their shape may sometimes look like a planet. A reflection nebula reflects the light that is cast upon its' dust, from nearby stars. They are often blue in colour. A good example of a reflection nebula is the nebula that formed the Pleiades cluster.