Starfish larvae use100000 hairs to stir the vortex.

Researchers at Stanford University have found that starfish larvae have evolved a mechanism that can not only stir water to bring food closer, but also push organisms forward to better foraging sites. In the prakash laboratory of Stanford University, before starfish grow into many armed and basically static adults, they sail on the sea as tiny larvae (about 1mm long, or about the size of rice grains) and propel themselves with 100. Scientists have recently discovered that there are 65,438+0,000 tiny hairs called cilia around their bodies.

But those hard-working cilia don't just help the larvae paddle forward.

Using high-speed cameras, the researchers found that swimming larvae are also using cilia to generate micro-eddies, which capture nearby algae to prey and push them to hungry swimmers. Scientists wrote in a new study that this efficient hunting behavior was previously unknown to starfish larvae, indicating that the application of cilia in marine invertebrates is far more complicated than previously thought. [What is spinning? Starfish larvae stir algae dinner | Video]

Free-swimming starfish larvae don't look like adults-they have tiny, transparent bodies, which are just the beginning of germination, and then they become arms. The author of this study decided to observe these very young forms more carefully in order to better understand the unusual bodies of starfish larvae and how they use them-"How physics shapes life", co-author Manu prakash, assistant professor of bioengineering at Stanford University in California, said in a statement.

The magnifying glass of the rotating periodic microscope has revealed the arrangement of thousands of cilia of starfish larvae, which help the larvae move forward, backward or change direction in a series of synchronous movements.

But the researchers found that the movement of another kind of cilia is beautiful, but puzzling.

When a group of cilia swim in the opposite direction to the larvae, a small vortex will be formed. The author of this study can observe the movement of water by implanting particles in it. These particles are illuminated on a black background, and then they capture the movement of water with a high-speed camera. Under the tracking of luminescent particles, many eddies can be seen around the larvae' bodies.

But what is the purpose of vortex motion? It takes a lot of energy to stir these eddies, and scientists want to know what good it is for larvae.

Further observation shows that when larvae are in places where there are a lot of algae, they will stir the vortex, generate electricity, and transport algae to hungry creatures, even at a distance several times the length of larvae. Once the food supply is exhausted, the larvae will swim away.

But there is a price to pay for producing efficient food conveyor belts. The researchers pointed out that the larva stirs its cilia to attract algae to approach, and it swims more slowly and disperses in the water, making it easier to be taken away by predators.

Although the water whirlpools hypnotized by larvae look fascinating-this video recently won the first prize in the Nikon Small World Dynamic Microscope Competition-researchers have found that they also have very special uses. According to the research of lead author William gilpin, a postdoctoral fellow in prakash Laboratory of Stanford University, their findings also show that cilia common in other tiny invertebrates may help them survive in a similar way.

"Evolution seeks to satisfy basic constraints," Gilpin said. The first effective solution often wins.

This discovery was published online in the journal Nature Physics on February 19.

This is an original article about life science.