COVID-19 is a contagious disease caused by the coronavirus SARS-CoV-2. In January 2020, the disease spread worldwide, resulting in the COVID-19 pandemic. The symptoms of COVID‑19 can vary but often include fever,[7] fatigue, cough, breathing difficulties, loss of smell, and loss of taste.[8][9][10] Symptoms may begin one to fourteen days after exposure to the virus. At least a third of people who are infected do not develop noticeable symptoms.[11][12] Of those who develop symptoms noticeable enough to be classified as patients, most (81%) develop mild to moderate symptoms (up to mild pneumonia), while 14% develop severe symptoms (dyspnea, hypoxia, or more than 50% lung involvement on imaging), and 5% develop critical symptoms (respiratory failure, shock, or multiorgan dysfunction).[13] Older people have a higher risk of developing severe symptoms. Some complications result in death. Some people continue to experience a range of effects (long COVID) for months or years after infection, and damage to organs has been observed.[14] Multi-year studies on the long-term effects are ongoing.[15] COVID‑19 transmission occurs when infectious particles are breathed in or come into contact with the eyes, nose, or mouth. The risk is highest when people are in close proximity, but small airborne particles containing the

Whales: Giants of the Ocean Whales are among the largest and most remarkable animals on Earth. These marine mammals live in oceans around the world, from warm tropical waters to the cold seas surrounding the poles. Life Beneath the Surface Although whales spend their lives in water, they breathe air through blowholes located on top of their heads. They must regularly return to the surface to breathe before diving again in search of food or traveling through the ocean. Whales are warm-blooded, give birth to live young, and nurse their calves with milk. A thick layer of fat called blubber helps protect them from cold water and stores energy during long migrations. Two Main Groups Whales are generally divided into baleen whales and toothed whales. Baleen whales filter small animals from the water using flexible plates inside their mouths. This group includes blue whales, humpback whales, and gray whales. Toothed whales use teeth to catch fish, squid, and other prey. Many of them also use echolocation, producing sounds and listening for returning echoes to understand their surroundings. Sperm whales, belugas, and orcas belong to this group. The Blue Whale The blue whale is the largest known animal to have ever

Whales: Giants of the Ocean Whales are among the largest and most remarkable animals on Earth. These marine mammals live in oceans around the world, from warm tropical waters to the cold seas surrounding the poles. Life Beneath the Surface Although whales spend their lives in water, they breathe air through blowholes located on top of their heads. They must regularly return to the surface to breathe before diving again in search of food or traveling through the ocean. Whales are warm-blooded, give birth to live young, and nurse their calves with milk. A thick layer of fat called blubber helps protect them from cold water and stores energy during long migrations. Two Main Groups Whales are generally divided into baleen whales and toothed whales. Baleen whales filter small animals from the water using flexible plates inside their mouths. This group includes blue whales, humpback whales, and gray whales. Toothed whales use teeth to catch fish, squid, and other prey. Many of them also use echolocation, producing sounds and listening for returning echoes to understand their surroundings. Sperm whales, belugas, and orcas belong to this group. The Blue Whale The blue whale is the largest known animal to have ever

Whales: Giants of the Ocean Whales are among the largest and most remarkable animals on Earth. These marine mammals live in oceans around the world, from warm tropical waters to the cold seas surrounding the poles. Life Beneath the Surface Although whales spend their lives in water, they breathe air through blowholes located on top of their heads. They must regularly return to the surface to breathe before diving again in search of food or traveling through the ocean. Whales are warm-blooded, give birth to live young, and nurse their calves with milk. A thick layer of fat called blubber helps protect them from cold water and stores energy during long migrations. Two Main Groups Whales are generally divided into baleen whales and toothed whales. Baleen whales filter small animals from the water using flexible plates inside their mouths. This group includes blue whales, humpback whales, and gray whales. Toothed whales use teeth to catch fish, squid, and other prey. Many of them also use echolocation, producing sounds and listening for returning echoes to understand their surroundings. Sperm whales, belugas, and orcas belong to this group. The Blue Whale The blue whale is the largest known animal to have ever

Whales: Giants of the Ocean Whales are among the largest and most remarkable animals on Earth. These marine mammals live in oceans around the world, from warm tropical waters to the cold seas surrounding the poles. Life Beneath the Surface Although whales spend their lives in water, they breathe air through blowholes located on top of their heads. They must regularly return to the surface to breathe before diving again in search of food or traveling through the ocean. Whales are warm-blooded, give birth to live young, and nurse their calves with milk. A thick layer of fat called blubber helps protect them from cold water and stores energy during long migrations. Two Main Groups Whales are generally divided into baleen whales and toothed whales. Baleen whales filter small animals from the water using flexible plates inside their mouths. This group includes blue whales, humpback whales, and gray whales. Toothed whales use teeth to catch fish, squid, and other prey. Many of them also use echolocation, producing sounds and listening for returning echoes to understand their surroundings. Sperm whales, belugas, and orcas belong to this group. The Blue Whale The blue whale is the largest known animal to have ever