The nucleus is missing in a mature RBC
Cephalochordates reproduce by releasing their eggs and sperm into the water, where they are fertilized externally. The fertilized eggs develop into free-swimming larvae that drift in the water for up to 200 days, feeding on plankton and other suspended matter, before settling down as adults.
<span>The state in which the body's systems are functioning smoothly and in equilibrium </span>is called homeostasis.
<span>Homeostasis is the tendency to maintain a balanced (relatively constant) internal environment and it can also be defined as the stable state of an organism. Homeostasis is maintained at many levels, not just the level of the whole body (blood sugar levels, pH, fluid balance…). Each of these is controlled by one or more homeostatic mechanisms (feedbacks for example).</span>