Size matters when it comes to animal and plant life: study

By Mark Waghorn via SWNS

Size really does matter - with large or small animals and plants most likely to survive, according to new research.

Life on Earth comes mainly in two sizes - tiny or huge - scientists said after five years of compiling and analyzing data about the size and biomass of every type of living organism on the planet.

The extremes have several advantages over rivals in the medium range - including getting enough food without becoming prey themselves.

The discovery is based on a survey of the planet's biomass - the first analysis of its kind.

It found the material that makes up all living organisms is concentrated at either end of the scale.

Humans have a relatively large body size putting them in the highest biomass category - shedding fresh light on their dominance.

Co-author Professor Malin Pinsky, of Rutgers University in New Jersey, said: "This conclusion - that life on Earth comes packaged predominantly in the largest and smallest sizes - surprised us.

"Sometimes it seems like mosquitoes or flies or ants must run the world, and yet, when we did the numbers, we found that our world is dominated by the microbes and the trees.

"These are the silent partners that recycle the nutrients and replenish the air all around us."

The blue whale is the biggest creature that ever lived. Its diet is based on krill - the ocean's most abundant prey.

The world's smallest mammal is the Etruscan shrew - only about an inch and a half long.

It has a voracious appetite - eating insects and other small animals.

They have remarkable metabolism - starving to death in one night without food.

Any carnivorous animal, including owls and raccoons, is a potential predator. Smallness helps it stay out of sight.

The international team spent five years compiling data on every type of known animal and plant.

They ranged from tiny one-celled organisms such as soil archaea and bacteria to blue whales and sequoia trees.

There are an estimated 8.7 million species in existence - of which only around 1.2 million have been identified and described so far. Most are insects.

The pattern favoring 'all creatures great and small' held across all types - and was more pronounced on land than in the water.

Lead author Dr. Eden Tekwa, now at McGill University in Canada, said: "The largest body sizes appear across multiple species groups - and their maximum body sizes are all within a relatively narrow range.

"Trees, grasses, underground fungi, mangroves, corals, fish and marine mammals all have similar maximum body sizes.

"This might suggest there is a universal upper size limit due to ecological, evolutionary or biophysical limitations."

The study in PLOS ONE opens the door to a better understanding of elemental life processes.

Prof. Pinsky said: "Body size is a fundamental feature of life - governing everything from metabolic rates to birth rates and generation times.

"Cataloging which body sizes are most common is a key step towards understanding the world around us."