Eucheuma cottonii (Kappaphycus alvarezii): This commercially important red seaweed is cultivated in tropical waters and is the leading source of kappa-carrageenan, a natural polysaccharide with gelling, thickening, and stabilizing properties. It is available in raw dried, chips, and alkali-treated chips, catering to various applications in food, pet food, cosmetics, and pharmaceuticals.