Over the last years, plethora of bioactive peptides have been isolated from organisms which live in sea water. Taking in account that more than two-thirds of the global surface area is covered with the oceans, marine species constitute above a half of the total biodiversity. Long-term evolution of marine organisms was advanced in the midst of pathogens, and efficient defense mechanisms were the necessary condition of their survival. Many marine peptides play a key role in host defense as evolutionary ancient components of innate immunity system [1]. They are involved in basic mechanisms of living organisms survival, including growth, defense, reproduction, and homeostasis. Protective peptides were isolated from many marine invertebrates and vertebrates. Their antibacterial, antifungal, antiviral, antitumor, antioxidative, antihypertensive, antiatherosclerotic, anticoagulant, antidiabetic, analgesic, immune-modulating, and neuroprotective properties attract increasing attention of pharmaceutical, cosmeceutical, and nutraceutical industries which focus on the design of innovative antibiotics, anticancer drugs, analgesics, medicines for neurological disorders, etc.