These Wild Dolphins Use Sea Sponges as Diving Masks

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Quick Take

• Some Indo-Pacific bottlenose dolphins in Shark Bay, Western Australia use sea sponges as tools to protect their snouts while hunting hidden prey, a behavior known as “sponging.”

• Sponging occurs only in a small portion of the population and is concentrated in specific habitats, suggesting it spreads through social learning rather than instinct.

• Dolphins select and wear sponges while probing rough seafloor areas, gaining access to prey but facing trade-offs such as reduced close-range echolocation sensitivity.

• Researchers view sponging as an important example of cultural transmission and tool use in marine mammals, highlighting dolphin cognition and the need to protect Shark Bay’s unique ecosystem.

Picture a dolphin diving toward the seafloor with something odd on its nose. It is not a shell or a fish. It is a sea sponge. The dolphin isn’t playing; it’s using the sponge as a diving mask: a clear example of tool use in a marine species.

In Shark Bay, Western Australia, some Indo-Pacific bottlenose dolphins use sponges as tools while they hunt. Researchers call the behavior “sponging.” The sponge acts like a soft shield as the dolphin probes sand and rubble for prey that hides out of sight. Only a small portion of the local population does this, and the behavior stays concentrated in certain parts of the bay. That pattern matters because it suggests the habit spreads through learning within social groups. Sponging is one of the best-known cases of tool use in a wild marine mammal. It also offers a window into how animals share skills across generations.

Indo-Pacific Bottlenose Dolphins in Shark Bay

The dolphins known for sponging in Shark Bay are Indo-Pacific bottlenose dolphins (Tursiops aduncus). This species lives mainly in warm, shallow coastal waters across parts of the Indian Ocean and the western Pacific. In Australia, they use bays, channels, and nearshore habitats where the seafloor offers many hiding places for fish. Indo-Pacific bottlenose dolphins have streamlined gray bodies and a curved dorsal fin.

Their snout, called a rostrum, is shorter than the snout of some other bottlenose dolphins. They usually travel in pods that change size and membership over time. These dolphins are highly social. They communicate with whistles and clicks, and they also use body signals such as leaps, tail slaps, and gentle contact. Their flexible behavior helps them adjust to changing conditions. It also makes it easier for new foraging habits, like sponging, to start and persist in a population.

Shark Bay’s Seafloor Sets the Stage

Shark Bay sits on the western coast of Australia and includes broad shallow waters, seagrass meadows, sandy flats, and rocky areas. That mix creates many microhabitats. Some spots have soft sand where prey can burrow. Other areas contain shells and rubble where fish can wedge themselves out of reach. Long-term research in Shark Bay has tracked individual dolphins and their family ties for decades. This type of monitoring helps scientists link behaviors to specific animals instead of guessing from brief sightings.

In Shark Bay, sponging does not show up at random across the whole region. It occurs mainly in certain channels and substrates where probing the bottom can pay off. That geographic pattern makes it easier to study how the behavior is learned and who uses it. It also hints that local ecology shapes whether sponging is worth the effort.

What “Sponging” Looks Like Underwater

Sponging begins with a dolphin selecting a marine sponge from the seafloor. The dolphin breaks it free and fits it over the tip of its rostrum. The sponge covers the snout like a thick glove. With that protection in place, the dolphin dives and pushes its nose into sand, gravel, or shell fragments. It sweeps side to side and probes crevices to flush out prey. When the dolphin detects movement, it may drop the sponge, grab the fish, and then pick the sponge up again.

Some dolphins use the same sponge across multiple dives, at least until it breaks apart. The technique allows dolphins to search places that can be risky for an unprotected rostrum. Sharp shells, abrasive rock, and stinging organisms can cause pain or injury. The sponge reduces that damage. In return, the dolphin gains access to prey that other dolphins may skip.

Why a Sponge Helps in Rough Habitat

A dolphin’s rostrum looks tough, but it is sensitive. It contains nerves that help the dolphin sense contact, vibration, and subtle movement. That sensitivity helps during hunting, yet it can also raise the cost of digging through harsh substrate. Sponging works because the sponge is soft and compressible. It absorbs impacts and creates a buffer between the dolphin’s skin and sharp surfaces. It can also reduce contact with spines or stinging animals that lie buried.

That protection changes how a dolphin can use its body during foraging. Without a sponge, a dolphin may avoid pushing its rostrum deep into rubble or shell beds. With a sponge, the dolphin can probe longer and with more force. Over time, fewer scrapes may mean fewer infections or less tissue damage. The sponge does not make the dolphin invulnerable, but it lowers the risk enough to make a difficult hunting niche possible.

Echolocation Trade-Offs and How Dolphins Adjust

Dolphins use echolocation to explore the world. They produce clicks and interpret the returning echoes. This helps them detect prey, map nearby objects, and navigate in low visibility. When a sponge covers the rostrum, it can change how sound moves near the tip of the snout. The signals can become muffled or less precise in the exact area the dolphin is probing. That creates a trade-off.

The sponge protects the rostrum, but it can also reduce sensory detail at close range. Sponging dolphins appear to compensate through behavior. They make repeated dives in small zones and use careful head movements near the bottom. They may rely more on repeated probing and close inspection once prey is disturbed. That adjustment takes practice. It also helps explain why sponging is not widespread. A tool that protects the body but complicates sensing can be hard to master. The dolphins that learn it gain access to prey that may be harder for others to reach.

Learning the Skill Through Social Teaching

Sponging is not an instinct that every calf performs automatically. Instead, it spreads through learning. In Shark Bay, researchers have found strong evidence that sponging is primarily passed down from mothers to offspring, though some males and non-maternal social learning have also been documented. Calves spend years close to their mothers, and that long childhood creates many chances to observe.

A young dolphin can watch how its mother selects a sponge, how she positions it, and how she searches the ocean floor. Calves also practice. Early attempts can look clumsy. The sponge may slip off, or the calf may drop it too soon. Over time, the calf improves and starts to use the tool more smoothly. This kind of learning is called cultural transmission. It means information spreads through social contact rather than through genes alone. Cultural transmission can create local traditions. In Shark Bay, it helps explain why sponging clusters in certain family lines and stays concentrated in particular habitats.

Why Most Spongers Are Female

In Shark Bay, most identified spongers are female, although recent studies have also documented male spongers. Scientists propose several reasons. Female dolphins often remain in more stable home ranges compared with males, which can make a specialized local technique more useful. Sponging also takes time. It involves slow, detailed hunting rather than quick chases. Male dolphins may spend more time traveling and building alliances with other males.

Those social demands can reduce the time available to refine a difficult foraging method. Another factor is learning style. If the behavior passes mainly from mother to calf, and daughters stay closer to their mother’s range, daughters may have more opportunity to learn and keep using the technique in the same habitat. Sons may disperse more or shift their focus to other strategies. Together, these factors help explain why the behavior remains more common among females in this population.

Costs, Benefits, and a Narrow Niche

Sponging has clear benefits, such as reduced competition. A sponger can access prey hidden in substrates that other dolphins may avoid. That can matter in habitats where food is patchy. Sponging may also provide a more reliable option when other prey types are scarce.

This behavior also carries real costs. Sponging can be slow and energy demanding. A dolphin may spend long periods probing and making repeated dives. The sponge can also reduce sensory sharpness at close range, which may require extra effort to locate prey. Learning the technique can take years, so a calf needs time and repeated exposure. These costs help explain why only a small part of the population becomes spongers. The behavior seems to work best in specific environments within Shark Bay. If the habitat changes, the balance could shift. The fact that the behavior persists suggests that, for those dolphins, the payoff remains high enough to justify the effort.

A Cultural Lens on Ocean Life

The image of a dolphin wearing a sponge is more than a surprising sight. It highlights a key point about animal behavior. The ocean contains not only species but also learned traditions. In Shark Bay, sponging persists because dolphins live long lives, raise calves over many years, and maintain strong social bonds. Those conditions allow information to pass from one generation to the next.

Sponging also shows how ecology and culture interact. A tool becomes useful in a specific habitat, and social learning helps the technique spread within certain lines. Over time, the behavior becomes part of the local “way of life.” Paying attention to these patterns changes how people think about marine animals. Dolphins are not only reacting to their environment in the moment. They also draw on learned knowledge that can shape how they forage, where they spend time, and how they survive. When researchers study behaviors like sponging, they gain insight into how animal societies store information and adapt to complex environments.

The post These Wild Dolphins Use Sea Sponges as Diving Masks appeared first on A-Z Animals.