| A | B |
|---|
| Vertebrae | Segments of bone or some other hard substance that are arranged into a backbone |
| Notochord | A rod of tough, flexible material that runs the length of a creature's body, providing the majority of its support |
| Endoskeleton | A skeleton on the inside of a creature's body, typically composed of bone or cartilage |
| Bone marrow | A soft tissue inside the bone that produces blood cells |
| Axial skeleton | The portion of the skeleton that supports and protects the head, neck, and trunk |
| Appendicular skeleton | The portion of the skeleton that attaches to the axial skeleton and has the limbs attached to it |
| Closed circulatory system | A circulatory system in which the oxygen-carrying blood cells never leave the blood vessels |
| Arteries | Blood vessels that carry blood away from the heart |
| Capillaries | Tiny, thin-walled blood vessels that allow the exchange of gases and nutrients between the blood and the cells of the body |
| Veins | Blood vessels that carry blood back to the heart |
| Olfactory lobes | The lobes of the brain that receive signals from the receptors in the nose |
| Cerebrum | The lobes of the brain that integrate sensory information and coordinate the creature's response to that information |
| Optic lobes | The lobes of the brain that receive signals from the receptors in the eyes |
| Cerebellum | The lobe that controls involuntary actions and refines muscle movement |
| Medulla oblongata | The lobes that coordinate vital functions, such as those of the circulatory and respiratory systems, and transport signals from the brain to the spinal chord |
| Internal fertilization | The process by which the male places sperm inside the female's body, where the eggs are fertilized |
| External fertilization | The process by which the female lays eggs and the male fertilizes them once they are outside of the female |
| Oviparous development | Development that occurs in an egg that is hatched outside the female's body |
| Ovoviviparous development | Development that occurs in an egg that is hatched inside the female's body |
| Viviparous development | Development that occurs inside the female, allowing the offspring to gain nutrients and vital substances from the mother through a placenta |
| Anadromous | A life cycle in which creatures are hatched in fresh water, migrate to salt water as adults, and then go back to fresh water in order to reproduce |
| Bile | A mixture of salts and phospholipids that aids in the breakdown of fat |
| Atrium | A heart chamber that receives blood |
| Ventricle | A heart chamber from which blood in pumped out |
| Ectothermic | Lacking an internal mechanism for regulating body heat |
| Hibernation | A state of extremely low metabolism and respiration, accompanied by lower-than-normal body temperatures |
