Lion's mane jellyfish: Top 10 largest underwater animals with long tentacles, resembling a lion's mane. Found in calm waters, often entangled with debris.
Blue whales: Mysticeti Parvorder, largest known animals. Gray or dark on top, lighter underneath, with bluish tinge. Baleen whales, filter small crustaceans.
Sperm whales: Enormous toothed animals. Up to 18m long. Females reach size class less often. Worldwide in deep waters, solitary but social. Loud communication with clicks/whistles.
Whale sharks: Largest fish, up to 39ft long. Harmless to humans, feed on plankton. Gray with white spots, broad heads. Filter feeders, important for marine health.
Basking shark: Huge filter feeder, up to 29m long. Harmless, misunderstood as predator. Vital for marine balance, keeps fish populations in check.
Giant squid: Enigmatic, colossal creatures of the deep. Length up to 43ft, weight up to 606lbs. Rarely seen, mysteries yet to be unveiled.
Pacific Giant Octopus: Largest in family, spans Japan to California. Up to 16ft long, 600lbs. Intelligent hunters, aquarium favorites.