What makes people so special? Tool use, self-consciousness, language, and culture are high on the list, but in fact all of these characteristics can be found elsewhere in the animal kingdom. Humans and apes are close relatives, so it is perhaps not surprising that chimpanzees use tools or that gorillas (大猩猩) have a sense of fair play, even rejecting carrots (which they normally accept) when they see their neighbors getting grapes. But the qualities that we often think of as uniquely human exist not just on land, but in the ocean as well.

Among the invertebrates, octopuses (八爪鱼) are known for their intelligence, even exhibiting evidence of playfulness, tool use, and personality. But these skilled predators live alone and consequently lack culture. Dolphins, on the other hand, are large-brained, long-living, social- group-based predators, and it is here that we find the greatest similarity to human-like culture and awareness.

Culture depends on the ability of animals to pass on things they have learned to others. Many animals have culture in this sense, but what sets dolphins apart is what they pass on. Some bottlenose dolphins hold sponges in their mouths that they use as tools to sweep for fish hiding on the ocean floor. This ability is handed down through generations (especially in females), with some families — grandmother, mother, and daughter — all feeding in this highly specialized way.

Another characteristic that dolphins share with humans is their ability to recognize themselves in a mirror. When facing a mirror, most animals behave as though they are interacting with another individual. Even in humans, the ability to recognize that the image in a mirror is oneself does not occur before the age of 18 months. Dolphins not only recognize themselves, but if a black mark is put on the body of a dolphin, it will spend extra time at the mirror to look at the mark.

Despite the difficulties, the California coastal ecosystem is improving, largely thanks to the huge appetite sea otters (海獭) have for crabs. In a creative study, scientists revealed the return of otters to their former habitat in a Central California river mouth has slowed the decrease of the area’s river banks by up to 90%. “It would cost tens of millions of dollars for humans to rebuild these stream banks and restore these rivers. The otters are stabilizing them for free, in exchange for an all-you-can-eat crab feast,” said biology professor Brian Silliman, Ph. D. at Duke University.

Like many California river mouths, Elkhorn once was a habitat for otters, which need to eat around 20 to 25 pounds of food every day, with crabs being one of their favorite meals. But after fur traders hunted the local otter population nearly to extinction, the number of crabs exploded over the next century. Crabs dig into salt river soil, and over time can cause a salt river to wear away and collapse. Today, years after the otters returned, rivers and stream banks became more stable.

Angelini, one of the study’s authors, said that tool is an encouraging sign for her team as they face similar threats to Florida’s coastlines from sea level rise, storms, and extra nutrients overflowing into coastal waters. “All these seem unsurmountable,” Angelini said. “However, this study shows that, if we truly understand the ecosystem and know what tools to use, we can see significant benefits to the health and stability of these systems.”

The research team conducted large-scale surveys across 13 tidal (潮汐的) streams, as well as small-scale field experiments at five locations around the river mouth over a six-year period. Otters were not included in some lest sites but allowed to be used in others, using a caging system designed by Angelini.

“And all these years later, we now see these amazing results. It’s an inspiring story about the benefits of conservation and persistent, long-term research,” Angelini said.

Biology researcher Sayaka Mitoh loves studying Japanese sea slugs. Her research at Nara Women’s University sounds like something from out of scary movies. While studying these small, cute creatures in the lab one day, she saw something strange. A sea slug had cut off its own head but kept on living and moving. Then a couple more sea slugs did the same!

So, Mitoh and another researcher Yoichi Yusa tried it themselves. They cut off the heads of 16 sea slugs. Six of the creatures started regeneration. Three of them survived. One of the three even lost and regrew its body twice. And two different kinds of Japanese sea slugs went through the regeneration process.

Other creatures can lose body parts when needed. For example, some lizards drop their tails to get away from danger and regrow them later. This is a biological event called autotomy (自切).

“We think that this is the most extreme case of autotomy,” Yusa said. He added that some animals can autotomize their legs or tails but no other can drop their whole body.

One kind of sea slug can grow to 15 centimeters long. Scientists had long thought that a creature of that size could not survive without a heart to pump blood and nutrients to the brain.

When these sea slugs eat a certain type of algae (藻类), Yusa said, they can photosynthesize (光合作用) their food from sunlight and oxygen, just like a plant, for about 10 days. He guessed that after autotomy, the head sort of acts like a plant. It turns green and gets its energy from oxygen and sunlight. Mitoh and Yusa said that sea slugs probably developed this ability as a way of fighting off parasites (寄生虫).

Nicholas Curtis is a biology professor at Ave Maria University. What is especially interesting, he said, is that these sea slugs are more complex than other creatures that are known to regenerate. This discovery could help scientists better understand how to regenerate, or regrow, human tissue in the future.