Increase in carbon dioxide in your red blood cells which causes a drop in PH causes your breathing to speed up. If you hold your breath, rising carbon dioxide blood gas changes first leading to the urge to breathe. Carbon dioxide enters blood at the abdominal organs, hindlimbs, capillaries of the head.
Answer:
Invertebrates can have bilateral or radial symmetry, or they can be asymmetrical. Bilateral symmetry means that the animal is arranged in the same way on both sides. Radial symmetry means the body parts are arranged in a circle around a central point.