Deep Sea Giants: 40-Foot-Long Squids Tower Over Land Animals, Scientists Explore Why

The deeper you go, the bigger they get. This is an adage that applies to much of life eking out an existence in the crushing depths of our oceans. Near the surface, tiny crabs are terrified of larger predators. In the deep, 13-foot-wide, giant spider crabs are usually the predators themselves.

Perhaps the most infamous example of this deep-sea gigantism is the giant squid, capable of attaining lengths of over 40 feet and possibly even longer should it stretch out its tremendous tentacles. Giant isopods, giant jellyfish, even giant amoebas, the list goes on.

Introduction to Deep Sea Gigantism

The deeper you venture into the ocean, the more massive the creatures become. This phenomenon is known as deep-sea gigantism.

The extreme conditions of the deep sea, including cold temperatures, high pressure, and scarce food resources, favor the evolution of larger body sizes.

Popular Deep Sea Creatures: Giant Squid

The giant squid is possibly the most well-known denizen of the deep. Reaching up to 43 feet in length, these enormous cephalopods are a rare sight, with only a handful observed in their natural habitat.

They inhabit the oceanic abyss, prowling the lightless depths up to 3,000 feet down. Their elongated bodies and 10 sprawling tentacles are perfectly suited to snatch up prey in the pitch black.

Popular Deap Sea Creatures: Giant Isopod

Resembling a nightmare pillbug, the giant isopod can grow up to 16 inches long. They scavenge the sea floor, feeding on anything edible that falls from above.

With plated armor and menacing claws, the isopod has few natural predators. They move slowly to conserve energy in their harsh environment, crawling over deep ocean sediments.

Popular Deap Sea Creatures: Giant Spider Crab

The giant spider crab makes its home in the waters around Japan and New Zealand, with a leg span of up to 13 feet.

Despite their intimidating appearance, these massive crustaceans are generally harmless to humans and feed primarily on shellfish, seaweed, and decaying matter. They molt frequently due to their rapid growth, shedding their shell up to once a month.

Popular Deap Sea Creatures: Gulper Eel

True to its name, the gulper eel can swallow prey much larger than its size, thanks to a loosely hinged jaw and expandable stomach.

They inhabit ocean depths from 1,600 to 9,800 feet, making them challenging to study. Little is known about their feeding behaviors, but they are believed to consume crustaceans, cephalopods, and occasionally even other fish.

Popular Deap Sea Creatures: Hairy Anglerfish

The hairy anglerfish is one of the oddest-looking creatures of the abyss. Females can reach up to 3 feet in length, with a bioluminescent lure used to attract mates and prey.

Perhaps strangest of all is the tiny parasitic males, which attach themselves to the female’s body, slowly fusing until only their testes remain.

Theories Behind Deep Sea Gigantism: Metabolism

According to Kleiber’s law, larger organisms require less energy relative to their body mass to function. When food sources are scarce, as in the deep ocean, efficiency is key.

The giant squid would require far fewer calories to survive than a school of smaller squid with the same total mass.

Theories Behind Deep Sea Gigantism: Temperature Regulation

Bergmann’s rule states that organisms in colder climates tend to be larger. For warm-blooded animals, increased size means less surface area from which to lose body heat.

Although deep sea creatures are cold-blooded, lower temperatures also slow their growth, allowing some species to live for over a century. Their immense size is a result of this slow growth over many years.

Theories Behind Deep Sea Gigantism: Habitat

The deep sea habitat itself may drive some species to become enormous. With little light and scarce food, it pays to maximize your reach and grab anything edible that comes your way.

Some species have evolved mouths, stomachs, and tentacles of nightmarish proportions to capitalize on any feeding opportunity.

Kleiber’s Law Explained

The law stems from observations showing that as animals get larger, their metabolic rates increase at a slower rate than their mass.

In mathematical terms, if an animal is 100 times heavier than another animal, its metabolic rate will only be about 30 times greater.

Insulation and Heat Retention

Kleiber’s law may also relate to the greater volume and surface area of larger animals, which helps them retain more body heat.

Although deep sea creatures are cold-blooded, their immense size still provides some insulation and temperature regulation in the frigid depths.

How Kleiber’s Law Applies to Deep Sea Creatures

Kleiber’s law states that an organism’s metabolic rate scales with its mass to the 3⁄4 power. In simpler terms, larger animals require less energy per unit of body weight to survive than smaller animals.

For the giant beasts inhabiting the deep ocean, this mathematical relationship means they can get by on relatively little food.

Bergmann’s Rule and Polar Gigantism

According to Bergmann’s rule, animals living in colder climates tend to be larger in size compared to animals living in warmer climates. This is an adaptation that helps them retain body heat more efficiently.

Emperor penguins, for example, are much larger than penguins found in warmer habitats. Their increased size means they lose less body heat to the frigid Antarctic environment.

The Deep Water Mysteries Continue

The mysteries of the deep ocean are vast, but by studying the extremes of life found there, we gain insight into the rules that govern all organisms.

Whether it be the frigid temperatures, crushing pressures, or perpetual darkness, adaptations seen in giant squid, hairy anglerfish, and other outsized beasts reveal possible selective pressures.