Sharks evolved from early chondrichthyans during Devonian Period. Modern sharks (selachimorphs) appeared in Early Jurassic (200 million years ago). Sharks belong to clade Selachimorpha, sister group to rays. More than 500 species split across thirteen orders
Fennec fox is most popular, known for exceptional hearing. Fire bellied toad is least popular, appearing in multiple colors
Snakes are quiet, clean, and require minimum 75°F night temperature. Lizards are easy to care for and suitable for beginners. Birds provide companionship without requiring cuddling. Hamsters need regular cleaning but can be trained with patience. Fish offer anxiety relief through aquarium care
Dogs are friendly and intelligent with over 350 breeds worldwide. Newfoundland dogs are water-resistant and excellent lifeguards. Cats are friendly but territorial, with 37 species including tigers. Tigers can reach 13 ft and weigh up to 300 kg. Horses are fastest domestic animals with over 250 breeds
Insects have a global population of 10 quintillion individuals. Fish comprise 3.5 trillion individuals across 32,000 species. Birds are estimated at 50 billion individuals across 10,000 species. Reptiles have over 10,000 species globally. Sea anemones have over 1,000 known species
Oceans contain 97% of Earth's water and home to 230,000 known species. Only 5% of oceans have been explored, potentially over two million species. Most ocean animals live on ocean floor at different depths