The zygote, a single cell, implants its self to the uterine wall and it developes into an embyro which is a cluster of cells.
Lamprey and hagfish are jawless fish, with skeletons composed of cartilage. They do not have scales and are considered primitive fish. They are in the superclass cyclosystoma.
Ebolavirus, genus of viruses in the family Filoviridae, certain members of which are particularly fatal in humans and nonhuman primates. In humans, ebolaviruses are responsible for Ebola virus disease (EVD), an illness characterized primarily by fever, rash, vomiting, diarrhea, and hemorrhaging.