Sturgeons are 28 species of fish in family Acipenseridae. First appeared in Late Cretaceous, evolved from Early Jurassic fish. Family contains four genera: Acipenser, Huso, Scaphirhynchus, and Pseudoscaphirhynchus. Two species may be extinct in wild, one may be entirely extinct
Fish evolved from filter feeders 535-0 Ma ago. First jawed fish appeared in Silurian, "Age of Fishes". Bony fish evolved after end-Devonian extinction. Teleosts (96% of fish) are bony fishes with protruding jaws
Fish fins are movable appendages that generate thrust and help swim. Most fins are unpaired (dorsal, anal, caudal) and paired (pectoral, pelvic). Fins are supported only by muscles, not directly connected to back bone
Elephants are the largest living land animals with three recognized species. They have a prehensile trunk, tusks, large ear flaps, and pillar-like legs. Their brain is the largest of all terrestrial mammals. They evolved from proboscideans during the Miocene period
Africa has eight major physical regions with diverse wildlife. Each African country has its own national animal. Continent has some of world's most extraordinary biodiversity
Pets need nutritious food and clean water access daily. Safe housing space varies by pet type: dogs need 15cm extra length. Regular exercise and stimulation are crucial for all pets. Regular vet visits and vaccinations are necessary