Dolphin Tumor Necrosis Factor Alpha (TNF-α) (also known as TNF or cachectin) is a proinflammatory cytokine that plays a key role in innate immune responses, inflammation, and host defense against pathogens in dolphins, particularly the bottlenose dolphin (Tursiops truncatus). TNF-α is a member of the tumor necrosis factor (TNF) superfamily, which includes related cytokines such as TNF-β (lymphotoxin-α), Fas ligand (FasL), CD40 ligand (CD40L), and TRAIL, molecules involved in immune signaling, apoptosis, and inflammatory regulation. In dolphins, TNF-α is produced primarily by activated macrophages, monocytes, dendritic cells, and T lymphocytes in response to infection, tissue injury, or inflammatory stimuli. TNF-α exerts its effects by binding to TNF receptors TNFR1 (p55) and TNFR2 (p75), activating intracellular signaling pathways including NF-κB, MAPK, and caspase-mediated pathways, which regulate cytokine production, immune cell activation, apoptosis, and inflammatory responses. In marine mammals, TNF-α contributes to immune defense against bacterial, viral, and parasitic infections, while also helping coordinate inflammatory responses necessary for pathogen clearance. However, excessive TNF-α production may contribute to systemic inflammation or tissue damage during severe infections or environmental stress. Because dolphins are considered sentinel species for marine ecosystem health, characterization of dolphin TNF-α supports research on marine mammal immunology, host responses to infectious disease, and the effects of environmental contaminants or stressors on immune function, providing insight into immune regulation in marine mammals.