Tsunamis are known for their potential to cause huge devastation. The Boxing Day tsunami of 2004 – one of the deadliest of all time – killed over 220,000 people, injured hundreds of thousands more, and destroyed homes across several Asian countries. There are also disastrous outcomes for the animals caught up in them – particularly those who live in the affected oceans.
Tsunamis are caused when underwater geological events like earthquakes or volcanic eruptions displace the water and send waves rushing away, getting larger as they go. Waves as high as 30 metres can pummel into the shore at around 30 miles an hour.
Close to the source, bottom-dwelling species, including algae and molluscs, might be killed by the force but open ocean fishes could see little direct impact.
As the tsunami approaches land, it drags water offshore before the main waves hit. This drawback and the following strong waves could explain why several whales stranded on the Japanese Chiba prefecture in the 2025 tsunami.
When the powerful waves smash into the shoreline, turtle nests are washed away, nesting animals like Bonin Petrels are buried alive, and seabirds and mammals can drown or be swept away. After an earthquake in Japan in 2011, a baby porpoise was found stranded in a rice field over a mile inland.
An animal’s survival might depend on their choice of habitat – after Japan’s 2011 tsunami, adult abalone survived thanks to the protective kelp around them but juveniles died, dashed against the rocks. The loss of this younger generation was felt three years later when stocks suddenly dropped.
The force can also destroy fragile coral reefs, mangrove forests and seagrass meadows. Without these important ecosystems for shelter, many fish and critters are left without a home. Some corals take a year to grow just one centimetre so recovery could take decades.
Much of the wreckage from damaged towns and cities can end up back in the water and carried across the sea on currents. This can introduce harmful pollutants into the water, and the debris can also bring hitchhikers. In 2011, it was reported that nearly 300 different species were carried from Japan to the USA on tsunami debris. Invasive species harming native animals is another concerning ripple effect.
However, some creatures might be saved by the ability to sense that something bad is about to happen. Although this hasn’t been scientifically proven, eyewitnesses have reported elephants, cows, seabirds, turtles, and buffalo either acting strangely before tsunamis hit, avoiding their usual low-lying coastal habitats or travelling inland to find safe ground.
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