What is the primary function of the lymphatic system in animals?

The primary function of the lymphatic system in animals is to help defend the body against infections and diseases. This system consists of a network of lymphatic vessels, lymph nodes, and lymphoid tissues that play a crucial role in the immune response.

When the body is exposed to pathogens like bacteria and viruses, the lymphatic system works to identify and respond to these foreign invaders. Lymph nodes filter lymph fluid, trapping harmful microorganisms and facilitating the activation of immune cells, such as lymphocytes and macrophages, to fight off infections. Additionally, the lymphatic system is involved in the production and circulation of antibodies, which are critical for immunity.

The other options focus on functions that do not align with the primary role of the lymphatic system. For instance, transporting oxygen in the blood is a function of the circulatory system, particularly carried out by red blood cells. Supporting the respiratory system involves organs like the lungs, which manage gas exchange, rather than the lymphatic system. Aiding in digestion is primarily the role of the gastrointestinal tract and supporting organs rather than the lymphatic system, although it does play a secondary role in fat absorption from the digestive tract through absorption of dietary fats into lymphatic vessels known as lacteals.