The ocean is Earth’s largest and least-explored frontier. This curiosity about the unknown depths was captured by the mystery of the “Bloop,” a sound so loud it fueled speculation of a monster far larger than any known animal. While the truth behind this infamous sound is less sensational than the legend, the deep sea is still home to documented giants that dwarf nearly every other life form on Earth. We do not need to invent monsters when the real ones, from massive vertebrates to colossal invertebrates, are already swimming in the abyss.
The Bloop’s Legacy: Separating Speculation from Science
The “Bloop” became a global sensation after it was recorded in 1997 by hydrophones, or underwater microphones, placed throughout the Pacific Ocean. This ultra-low-frequency sound was powerful enough to be detected by sensors over 3,000 miles apart, suggesting an immense source for the noise. The acoustic signature was described as rising rapidly in frequency, which initially led researchers to consider a biological origin, perhaps a creature far larger than the largest whales.
The volume required for the sound to travel such a distance led to years of speculation. However, scientists from the National Oceanic and Atmospheric Administration (NOAA) later definitively identified the source of the Bloop. The true origin was not a hidden monster but a massive icequake, the sound generated by a large iceberg cracking and breaking away from an Antarctic glacier. The scientific consensus confirms that the sound’s characteristics match those of non-tectonic cryoseisms.
The Ocean’s Reigning Heavyweights: Vertebrate Giants
The definitive answer to what is bigger than the Bloop’s imagined creature is the blue whale (Balaenoptera musculus). It is the largest animal known to have ever existed on Earth, surpassing even the largest dinosaurs. Adult blue whales can reach lengths of up to 100 feet and weigh as much as 200 metric tons. This size is comparable to a passenger jet or about 25 to 30 adult elephants.
The heart of a blue whale is the largest in the animal kingdom, weighing around 400 pounds, roughly the size of a small car. Their main artery is so large a human could crawl through it, and their tongue alone can weigh as much as an elephant. Females tend to be slightly larger than males.
A newborn calf is already larger than most adult animals, entering the world at about 23 feet long and weighing 5,000 to 6,000 pounds. The blue whale is classified as a baleen whale, feeding on tiny krill through a specialized filter-feeding system, consuming up to 40 million krill per day. The whale shark (Rhincodon typus), another filter-feeding giant, holds the title for the largest fish, reaching lengths of up to 60 feet.
Deep-Sea Monsters: The Phenomenon of Abyssal Gigantism
The deepest parts of the ocean host a different kind of giant, often among the invertebrates, a phenomenon called abyssal gigantism. This is the tendency for deep-sea species to be significantly larger than their shallow-water relatives. The extreme environmental pressures of the deep sea drive this growth, including high hydrostatic pressure and low, stable temperatures that slow metabolic rates.
A slower metabolism allows animals to live longer and allocate more resources to growth over an extended lifespan, which is necessary in an environment where food is scarce. Larger body size also provides an advantage for energy storage, allowing these creatures to survive long periods between feeding opportunities. The most famous examples of deep-sea gigantism are the colossal squid (Mesonychoteuthis hamiltoni) and the giant squid (Architeuthis dux).
The giant squid holds the record for total length, with some individuals measured up to 43 feet from the tip of the mantle to the end of the longest tentacles. Conversely, the colossal squid is considered the heaviest invertebrate, with the largest specimens weighing up to 1,100 pounds, nearly double the weight of the giant squid. The colossal squid also possesses the largest eyes in the animal kingdom, with an estimated diameter of 12 to 16 inches, an adaptation that helps capture the faint light in the pitch-black abyss.