The ocean covers more than 70 percent of our planet and remains largely unknown and unexplored. However, within its deep trenches and sunlit coral reefs lie creatures of unimaginable scale and power. Whether you’re wondering which beast dominates the deepest waters or what kind of creature has enough venom to cast 26 in minutes, these records reveal the wonders hidden in the watery depths. Ocean Record Breakers The largest animal in the ocean… and the world! Blue whale (credit: SCIEPRO/Getty) Nine of the ten largest animals in the world are whales, and the tenth is the whale shark, the largest fish in the world (and often mistaken for a whale). The largest of the group is the blue whale, which can grow up to 33 meters in length. Females can weigh 180,000 kg, while males are around 150,000 kg. The largest shark in the ocean The enormous whale shark is the largest species of shark (and fish) in the world, reaching up to 20 m in length. Despite its enormous size, the whale shark is a gentle giant that consumes plankton through its filter-feeding method. It is, of course, one of the largest animals in the ocean. Deadliest Sea Snake in the Ocean Beaked Sea Snake (Credit: ePhotocorp/Getty) The deadliest sea snake category is a little difficult to judge. The Dubois sea snake has the most toxic venom of all snakes, but it is the beaked sea snake that causes the most human deaths year after year. Up to 90 percent of human deaths from sea snakes are due to this particular species. Their victims are usually fishermen, who come into contact with the snakes when they collect their nets. They have an aggressive nature and can attack when perceived threatened. The largest coral colony in the ocean The largest coral ever recorded was discovered by scientists in 2024. The megacoral, a collection of many creatures that together form a single organism (rather than a coral reef), was found in the Solomon Islands in the southwestern Pacific Ocean. It measures a staggering 34m wide and 32m long. Experts believe that this mega coral, which can be seen from space, is about 300 years old. Longest invertebrate in the ocean The rarely seen giant squid is the longest invertebrate on Earth, with tentacles extending up to 13 m in length. But when it comes to weight, another squid takes the top prize. The Heaviest Invertebrate in the Ocean Although the colossal squid is shorter than the giant squid, it weighs much more. While the heaviest giant squid on record weighed 220 kilograms, the heaviest colossal squid weighed around 495 kg. The largest mouth in the ocean Bowhead whale family swimming together (credit: Stanislav Stelmakhovich/Getty) The bowhead whale’s mouth measures five meters long, a third of its total body length, making it the largest mouth in the animal kingdom. As a result, it has a vocal repertoire rivaled by only a few species of songbirds. One study found that the bowhead whale develops a new set of songs each season. Unlike the humpback whale song, which has a more formal structure, the bowhead whale song is much freer and non-repetitive. Deepest point in the ocean The deepest known point in the ocean is the Challenger Deep in the Mariana Trench of the western Pacific Ocean. It is believed to reach depths of nearly 11 kilometers (7 miles) below the ocean surface. The largest toothed whale in the ocean Group of sperm whales in a social group, Indian Ocean, Mauritius (credit: wildestanimal/Getty) Sperm whales are the largest of all sperm whales; In fact, they are so large that they are often grouped together with large whales, measuring up to 20 m. A sperm whale weighs the same as nine elephants and is the largest active hunter on the planet, hunting prey in the deep ocean, including giant squid, sharks and other marine mammals. The loudest animal in the ocean The loudest animal in the world makes its sounds underwater: the blue whale. It emits booming calls, known as “songs,” that are loud enough to cause permanent damage to human eardrums, recorded at over 180 decibels (dB). The deadliest animal in the ocean Box jellyfish in Western Australia (credit: Brett Monroe Garner/Getty) The Australian box jellyfish, also known as the sea wasp, is believed to be the most dangerous jellyfish in the world and carries lethal toxins that have a rapid effect, causing paralysis and cardiac arrest in as little as five minutes. There are 50 different species of box jellyfish, and only eight are capable of killing humans, with the Australian box jellyfish believed to be the deadliest. In fact, they are considered the most dangerous animal in the ocean and are believed to cause between 40 and 100 deaths each year, although this number may be much higher due to undocumented deaths. The largest coral reef in the ocean The Great Barrier Reef is the largest coral reef system in the world, covering approximately 133,000 square miles off the coast of Queensland, Australia. Unfortunately, the reef has declined significantly in terms of live coral cover in recent decades, as a result of repeated heatwaves and mass bleaching. Long-term studies show that the reef has lost more than half of its coral populations since the mid-1990s. The largest heart in the ocean The heart of a blue whale is the largest in the animal kingdom; the largest on record weighs 440 pounds, the weight of three adult humans. The deadliest octopus in the ocean While all octopuses are venomous, the venom of some particular species is more toxic than others. The most poisonous octopus of all is considered to be the blue-ringed octopus. Although only about the size of a golf ball, the blue-ringed octopus contains enough venom in its body to kill 26 adult humans in a matter of minutes. Furthermore, there is no known antidote. The fastest swimmer in the ocean Sailfish off the coast of Isla Mujeres, Mexico (credit: Alastair Pollock Photography/Getty) There are two at the top of the podium for the fastest fish award: the sailfish and the bluefin tuna. At a fishing event in Florida in the early 1900s, a hooked Indo-Pacific sailfish reportedly pulled out 91 meters of line in three seconds, equivalent to a speed of 110 km/h (68 mph). However, bluefin tuna can accelerate faster, having been recorded reaching speeds of 232 km/h (144 mph) in two seconds, compared to 126 km/h (78 mph) for sailfish. The largest brain in the ocean The largest brain on Earth lives in the ocean: it is the sperm whale. The average brain weight of an adult male sperm whale is 7.8 kg, compared to 1.4 kg for a human. In fact, a sperm whale’s head makes up one-third of its total body length. The largest crustacean in the ocean Giant Japanese spider crab (credit: Ken Usami/Getty) The Japanese spider crab has a leg span of 3.69 m (yes, that’s longer than a king-size bed) but, surprisingly, it’s not the heaviest crustacean. Heaviest crustacean in the ocean While the Japanese spider crab takes the crown for largest marine crustacean, the American lobster is the heaviest. The heaviest specimen was discovered off the coast of Nova Scotia, Canada, in 1977, weighing 20.14 kg. Sharpest teeth in the ocean The conodont, an extinct eel-like marine vertebrate, had the sharpest teeth ever recorded in the animal kingdom, with microscopic teeth tapering to a tiny, incredibly sharp tip. The largest jellyfish in the ocean The lion’s mane jellyfish was long thought to be the largest jellyfish in the world, but biologists now believe that the Nomura jellyfish is the largest. Weighing up to 200 kg, the bell of the Nomura jellyfish measures up to 2 meters in diameter.
