Chondrichthyes
Nota de aplicación
A class of very ancient vertebrates including sharks, rays, skates, and chimaeras, that are characterized by having a cartilaginous skeleton, and typically a notochord present in the young that is gradually replaced by cartilage, a relatively large brain weight relative to body size, red blood cells produced in the spleen and special tissue around the gonads rather than in bone marrow, unique Leydig's organ and epigonal organ that may be part of …