The Marine Mammal Center weaning. At the center, they receive specialized veterinary care; diagnosed, treated, rehabilitated, and ideally, released back into the wild. Animals in need of assistance are usually identified by a member of the public who has contacted the center. These animals represent the following major species: California sea lion, northern elephant seal, Pacific harbor seal, northern fur seal, and the southern sea otter. On a few occasions, the Marine Mammal Center has taken in Guadeloupe fur seals, Steller sea lions, and bottlenose/Pacific white-sided dolphins. The only non-mammals that the center takes in are sea turtles. The research team consists of veterinarians
Mammal determination system]] different from that of most other mammals. In particular, the [[sex chromosome]]s of a platypus are more like those of a chicken than those of a therian mammal. Viviparous mammals are in the subclass Theria; those living today are in the marsupial and placental infraclasses. Marsupials have a short [[gestation]] period, typically shorter than its [[estrous cycle]] and gives birth to an undeveloped newborn that then undergoes further development; in many species, this takes place within a pouch-like sac, the [[Pouch (marsupial)|marsupium]], located in the front of the mother's [[abdomen]]. This is the [[Symplesiomorphy|plesiomorphic]] condition among viviparous mammals;