Aug 04, 2026 12:02:00

It has been revealed that dolphins that use sponges to find food have undergone genetic changes.

by Holterscan

Some bottlenose dolphins living in Shark Bay off the coast of Western Australia engage in a foraging behavior called 'sponging,' where they attach sponge-like marine organisms to their snouts and search for food on the seabed. It has now been revealed that this sponging has a unique effect on the dolphins' genes.

A culturally transmitted foraging technique in Indo-Pacific bottlenose dolphins can be predicted by DNA-methylation levels | Philosophical Transactions of the Royal Society B | The Royal Society
https://royalsocietypublishing.org/rstb/article/381/1955/20250017/482594/A-culturally-transmitted-foraging-technique-in

Sponge Foraging in Dolphins Does Something Unique to Their Genes : ScienceAlert
https://www.sciencealert.com/some-dolphins-use-tools-and-it-does-something-unique-to-their-genes

Some bottlenose dolphins living in Shark Bay perform a technique called 'sponging,' where they cover their snouts with sponges to search for fish and other prey on the seabed. Sponging is thought to have several advantages, including protecting the snout from friction against rocks and sand on the seabed and allowing them to search a wider area at once than they could with their snout alone.

Sponging in bottlenose dolphins has been a known behavior for over 25 years and is believed to be a technique passed down from mother to calf. However, it is not easy for dolphins to learn because covering their snouts with sponges impairs their echolocation abilities. The following video shows a dolphin with a sponge attached to its snout.

Dolphins in Australia seen using sponges to protect their snouts as they look for fish on seabed - YouTube


Sponging dolphins spend more time foraging and often hunt alone, but it has also been observed that they form closer bonds with other sponging dolphins . However, it seems that some individuals, despite living in the same ocean area and being closely related to sponging individuals, never learn to sponge.

Therefore, a research team led by Michael Klutzen, an evolutionary biologist at the University of Zurich in Switzerland, conducted a study to investigate the epigenetic changes that occur in dolphins that perform sponging.

Epigenetics refers to the mechanism by which the function of genes is controlled while the DNA sequence itself remains unchanged. The field of study that investigates epigenetics is called epigenetics. A well-known example of epigenetic change is DNA methylation , in which a methyl group is added to a DNA molecule.

DNA methylation is generally described as changing the 'on/off' state of genes, but according to the science media outlet ScienceAlert, it's more like a 'dimmer switch' that provides gradual control. DNA methylation patterns are known to change depending on age, diet, stress, and environmental conditions, and may reflect differences in lifestyle.

The research team analyzed skin samples from 96 dolphins collected over more than 20 years to investigate what kind of DNA methylation occurs in dolphins that perform sponging. Of the 96 dolphins, 23 had the habit of sponging, while the remaining 73 did not.

We investigated approximately 30,000 potential DNA methylation sites throughout the dolphin genome and tested whether a machine learning model could distinguish between individuals that underwent sponging and those that did not. We found that it could distinguish between the two with moderate accuracy.

After correcting for tens of thousands of statistical comparisons, no single methylation site stood out, and the predictive signal was dispersed across many small differences. The final model was reported to be built based on methylation patterns at 21 DNA sites, rather than on a single prominent gene marker. This result suggests that complex behaviors are controlled not by a single gene or molecular pathway, but by multiple pathways.

Sponging-like foraging behaviors may influence diet, social life, energy consumption, and environmental coping, potentially leading to patterns in DNA methylation. However,

studies on nematodes suggest that epigenetic changes can also be passed down through generations.

Therefore, the question remains unanswered as to whether sponging alters the methylation pattern, whether the existing methylation pattern influences sponging, or whether both methylation patterns and sponging are shaped by common factors. Furthermore, this study analyzed DNA from the skin, which may not fully reflect the changes occurring in the brain and other organs.

by Vince Smith

Evolutionary biologists have long gained a deeper understanding of how culture can shape genes across generations, with the spread oflactose tolerance among dairy farmers being one example. ScienceAlert stated, 'This study, along with other studies examining epigenetic changes, suggests that there may be ways in which the body can more quickly communicate survival strategies and improvements in nutritional status by leveraging the biological messaging of the epigenome.'