Final answer:
The spleen's functions involve filtering blood, removing old red blood cells, storing platelets and iron, but it does not contain crypts that trap bacteria, which is a function of other lymphatic tissues.
Step-by-step explanation:
The functions of the spleen include the removal of old or defective red blood cells, the storage area for blood platelets, and the storage area of iron, as well as filtering the blood to remove antigen-coated bacteria and other blood-borne pathogens. However, the spleen does not contain crypts that trap bacteria; this function is attributed to the tonsils and other lymphatic tissues. Thus, the correct answer is that the spleen does not 'contain crypts that trap bacteria'.