Quick Answer. Five short blasts from a boat on the water signal that the pilot of the boat doubts the action of another nearby craft trying to avoid a collision, according to the New South Wales Roads & Maritime Services. These signals also mean the pilot of the ship has concerns about the proximity, course and speed of a nearby boat.
Aspect of two species that are equivalent as a consequence of, that is, aspects that are homologous. Shared characters can either either be unique to a taxon (and therefore represent a shared derived character) or instead may be shared with other, related taxa (and therefore represent a shared ancestral character). In either case, shared characters are. The distinction is in how far back one has to go to reach the ancestor in which the shared character first arose. Only if one need not leave a specific clade to reach that ancestor is the character described as a shared derived character.
Node: the last point at which the two new lineages shared a common ancestor. Derived character: a trait that arose in the most recent common ancestor and was passed along to its descendants. Smaller clades are nested within larger clades.Whether or not a character is derived depends on the level of grouping. Example: Hair is a derived character for the clade Mammalia but four limbs is NOT a derived character for the clade Mammalia. If it were then only mammals would have that trait. clade must be a monophyletic group (includes a single common ancestor and all of its descendants). NOTE: Some of the taxa in the Linnaean classification system were paraphyletic meaning the group includes a common ancestor but excludes one or more groups of descendants.