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.
1 A homoplasy is a shared trait found among different taxa but inferred to have been independently derived and not to have occurred in their common ancestor (i.e., a trait considered to be the same emerged in different taxa independently of each other). 2  An example of this is homeothermy in birds and mammals.hether or not a trait is considered derived depends on the group in question. For example, among the (crown group) tetrapods, having five fingers is the primitive trait-as their last common ancestor bore a five-digit hand.