This tadpole shrimp is coming for your rice.

Hungry hordes of them find their way into the  rice fields of California’s Central Valley   and go to town munching on the young seedlings.

But where did they come from,  with the ocean so far away?

A couple of weeks ago, this  was just a dry dusty field.

Turns out they were here all along.

They’re time travelers waiting for months,  years, even decades in the sun-baked soil.

Each spring, when rice farmers flood  their fields and scatter their seeds they   inadvertently create the perfect conditions  for billions of tadpole shrimp to awaken.

The egg’s rugged outer shell called the chorion   cracks open and the larva wiggles  its way out of a translucent sac.

Tadpole shrimp aren’t really  tadpoles, they aren’t even shrimp,   though they are crustaceans whose  ancestors evolved in the sea.

The tiny larvae forage through the mud  incessantly for any food they can dig up.

They’re not picky.

But as they grow they really  acquire a taste for rice plants.

They chomp away at the first tender roots and  leaves just when the seedling needs them most.

Without roots to hold them down  the young plants just float away.

And if it loses its first leaves a  seedling can’t get enough energy to grow.

As if that’s not enough, the throngs of tadpole  shrimp stir up the mud, blocking out the sun.

But the rice plants that do manage to  break the water’s surface are safe.

Their roots and stems are thick and tough  enough that the tadpole shrimp leave them alone.

At that point tadpole shrimp  are actually kind of helpful.

They turn their appetites to any weeds  that make their way into the rice field.

They even eat the larvae of mosquitoes that  could carry West Nile virus when they grow up.

Once the tadpole shrimp mature, they lay  their eggs in the mud and then they’re done.

Adult tadpole shrimp only live for about a month.

The secret to these armored  arthropods' survival is their eggs.

At the end of the growing season,   farmers drain their fields so they  can harvest the rice on dry ground.

No water?

No problem.

The eggs can survive being  completely dehydrated for years.

Their tough outer shell protects them from  scorching heat, freezing cold, even time itself.

The embryos inside just stop developing.

They enter a suspended state called diapause.

That’s what keeps them from  hatching in a dry field.

When the water returns, and conditions are  right again, they’ll be ready to hatch.

That’s because tadpole shrimp evolved  to live in temporary freshwater ponds,   created by seasonal rains  throughout North and South America.

It’s how they endure having  their ponds dry up each year.

They’ve been living this way for  hundreds of millions of years--   since before the dinosaurs-- waiting out droughts,  changing climates, even global catastrophes.