Convergent Buoyancy System Sinks Evolutionary Paradigm

Question: What do the massive sperm whale and the microscopic copepods have in common?

They both live in the ocean, true, but that’s not what I had in mind.

Answer: Both creatures use the same buoyancy control mechanism, according to research recently published by two researchers from the British Antarctic Survey.1 This work has identified another remarkable example of convergence in the biological realm and, with it, raises questions about the validity of the evolutionary paradigm.

Sperm Whale Bouyancy
The spermaceti, a large organ in the sperm whale’s head, helps control this behemoth’s buoyancy in the water. The organ contains a vast amount of fatty materials. When the whale is at the surface, the fat exists in liquid form. The fat solidifies when cold water enters the organ and restricts blood flow.

This change increases the fat’s density and generates a downward force that allows the sperm whale to dive without much effort. When it is time to surface, increased blood flow to the spermaceti organ melts the fat, creating positive buoyancy that enables the animal to surface with ease.

Copepod Buoyancy
Copepods are tiny crustaceans that live in aqueous environments around the world.

Copepods that live near Antarctica will spend the winter deep in the ocean waters in a state of hibernation (called diapause). While in diapause, the copepod’s metabolic activity is reduced drastically. For the animal to remain at great depths without expending much energy requires a mechanism to establish and maintain neutral buoyancy.

After spending the summer and fall feeding on phytoplankton, over half a copepod’s body by volume can be occupied by fat right before winter. The work by the British Antarctic Survey scientists indicates these fat stores allow the copepods to achieve neutral buoyancy in the deep ocean. The researchers discovered a correlation between fat content of copepods and the depth at which they are found. The scientists also showed that at ocean temperatures and depths of 500 meters the fats—which are liquid at the ocean surface—undergo a transition to a solid state. When this happens the fats increase in density, thus supporting neutral buoyancy when the copepods are well below the surface.

The Challenge to the Evolutionary Paradigm
From an evolutionary standpoint, it looks as if an identical buoyancy control mechanism evolved independently in sperm whales and copepods. The very nature of the evolutionary process rests on sequences of improbable, chance events; thus, it should not generate identical outcomes multiple times. Yet it looks as if this repetition has indeed occurred over and over again.2 Widespread convergences provide important ground for skepticism toward evolutionary explanations for life’s diversity and history.

The Case for Intelligent Design
Meanwhile, repeated outcomes make sense from a design perspective. It is common for designers to reuse the same concepts. Accordingly, the use of the same buoyancy control mechanism in sperm whales and copepods could be understood to reflect the work of a Creator who employed the same design strategy in these two radically different organisms.


  1. David W. Pond and Geraint A. Tarling, “Phase Transitions of Wax Esters Adjust Buoyancy in Diapausing Calanoides acutus,” Liminology and Oceanography 56 (2011): 1310–18.
  2. Read about other examples of convergence: “Convergence Drives Evolution Batty,” “Convergence: Evidence for a Single Creator,” “Déjá-vu—Again, Part 1,” and “Déjá-vu—Again, Part 2.”

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