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.
Derived trait. In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary loss.Here the lack of a structure is a derived trait.or example, among the tetrapods, having five fingers is the primitive trait-as their last common ancestor bore a five-digit hand. However, amongst the vertebrates, five fingers is a derived trait, as the last common ancestor to the vertebrates did not even bear fingers.