Deep Sea Gigantism | Why the Ocean Breeds Giants

updated 13 Jun 2023

Deep sea gigantism refers to the phenomenon of marine animals in the deep ocean growing to unusually large sizes compared to their shallow-water counterparts. It is a well-documented phenomenon observed in various groups of organisms, including invertebrates and fish.

Deep Sea Gigantism

The exact causes of deep sea gigantism are not fully understood, but several factors have been proposed to contribute to this phenomenon:

  1. Reduced predation pressure: In the deep sea, predators are generally scarce compared to the shallow waters. With fewer predators, larger body sizes may provide an advantage in capturing prey or defending against occasional predators.

  2. Increased resource availability: The deep ocean is characterized by relatively low food availability. This scarcity of resources may lead to competition among organisms. Growing larger allows these organisms to have a higher feeding efficiency and exploit scarce resources more effectively.

  3. Lower metabolic rates: Deep-sea organisms often have slower metabolic rates compared to their shallow-water counterparts. Lower metabolic rates can result in slower growth rates and delayed maturation, allowing organisms to grow larger over extended periods of time.

  4. Cold and stable environment: The deep ocean is characterized by cold temperatures and stable environmental conditions. These factors can contribute to slow growth rates and longer lifespans, providing more time for organisms to reach larger sizes.

Kleiber's Rule

Examples of deep sea gigantism include giant isopods, which can reach lengths of over 30 centimeters, colossal squid, which are known to grow up to 14 meters in length, and the giant oarfish, which can reach lengths of up to 11 meters. These are just a few examples, and there are many other species that exhibit deep sea gigantism.

It's important to note that deep sea gigantism is not observed in all deep-sea organisms. Many species in the deep ocean are small or have similar sizes to their shallow-water relatives. The phenomenon is more common in certain taxonomic groups and specific ecological niches.

Overall, deep sea gigantism is a fascinating aspect of marine biology that highlights the unique adaptations of organisms to the extreme and challenging conditions of the deep ocean.