Meet hydra, the shape-shifting Dr Manhattan of the animal kingdom

Jul 15, 2014 by Rebecca Helm
Indestructible. microagua, CC BY-NC-SA

In the comic series Watchmen, physicist Jon Osterman is blown apart in a science experiment gone awry. But his "consciousness" is able to pull his body back together atom by atom, becoming the radiating, blue-skinned Dr Manhattan. It took him months to reform, and in that time I wonder if he learned that trick from a tiny pond animal. For few creatures in fiction, and even fewer in real life, are capable of surviving being ripped to bits. But for hydras, it is an every day affair.

Hydras are tiny freshwater animals, with column-shaped bodies ringed at the top with tentacles around a mouth. Like little freshwater sea anemones, hydras spend much of their time with tentacles extended, waiting for prey to pass. Not exactly comic book material. But to see their true power, all you have to is blend a Hydra to hamburger meat and swirl the puree to the bottom of a bowl.

Slowly, the disembodied pieces will begin crawling together, rising like tiny volcanoes from the sea of shredded remains. Forms will begin to take shape. Mouths and skinny tentacles stretching out into the water, and suddenly little bodies everywhere have regrown.

Ulrich Technau of the University of California at Berkeley and his colleagues wanted to find out what gives hydras this incredible ability. The secret, they discovered, to surviving being blown apart is all about keeping its head.

The Hydra's head isn't much to look at. It has a mouth and some . But instead of housing brains, hydras use their heads to constantly send signals telling the rest of their where to go and what to be. When a is turned into puree, its head is scattered into bits. But if even a few cells keep their identity as head cells, that is all a hydra needs to regrow.

Hydra cell mounds after 24 hours (top), and new Hydras taking shape after 96 hours (bottom). Cells in blue that are part of the new head command centres. Credit: Ulrich Technau/PNAS

According to the Technau and his colleagues, hydra need is between five and 20 of these command cells to form a new body. These cells will take charge, barking out cellular orders that pull the rest of the cells in line. Once a cellular mound has formed around these command cells, it is just a matter of each member of the mound falling into place, and a new animal has grown where before there was only mincemeat.

Because there are many more than 20 cells in the original hydra head, and because these cells will be spread haphazardly when the animal is ground down, these cells will command multiple mounds to form and make new bodies. One animal becomes many.

For the hydra at least, this neat trick may mean fast recovery from predator attacks in the wild. If even a small piece is left after being eaten alive, there is hope of survival. But does it have any implications for those of us who, as a general rule, do not survive being blown to bits? If any, the implications are limited. We do not have an organising centre like hydra (at least not as adults), and so we are not going to find reassembly quite so easy. Unless, of course, we're blown apart in the same mad that disintegrated Jon Osterman. Few will ever be as lucky as Dr. Manhattan and the minuscule hydra.

Explore further: Discovery of a primordial cancer in a primitive animal

add to favorites email to friend print save as pdf

Related Stories

Earthquake model explains Hydra's regenerative prowess

Apr 30, 2012

When the Greek hero Hercules sliced through one of the Lernaean Hydra's nine heads, two grew back in its place. This mythical creature's real life counterparts, a genus of tiny cylindrical animals known as ...

'Orphan' genes play an important role in evolution

Nov 18, 2008

Closely related animal species share most of their genes and look almost identical. However, minor morphological differences allow us to tell them apart. What is the genetic basis for these differences? Often, the explanation ...

Biologists sequence Hydra genome

Mar 14, 2010

UC Irvine researchers have played a leading role in the genome sequencing of Hydra, a freshwater polyp that has been a staple of biological research for 300 years.

Discovery of a primordial cancer in a primitive animal

Jun 24, 2014

Every year around 450,000 people in Germany are diagnosed with cancer. Each one of them dreams of a victory in the battle against it. But can cancer ever be completely defeated? Researchers at Kiel University ...

Recommended for you

Vietnam's taste for cat leaves pets in peril

2 hours ago

The enduring popularity of "little tiger" as a snack to accompany a beer in Vietnam means that cat owners live in constant fear of animal snatchers, despite an official ban.

New species of mayfly discovered in India

4 hours ago

Scientists have discovered a new species of mayfly in the southern Western Ghats, a mountain range along the west coast of India. In fact, this is the first time that any mayfly belonging to the genus Labiobaetis has be ...

Rising temperatures can be hard on dogs

Jul 25, 2014

The "dog days of summer" are here, but don't let the phrase fool you. This hot time of year can be dangerous for your pup, says a Kansas State University veterinarian.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Moebius
not rated yet Jul 15, 2014
If he was blown apart and put back together (correctly) he would be the same as before.