Animal Foraging Tactics Unchanged for 50 Million Years
The study of fossilized sea urchin trails revealed that for the past 50 million years, animals have used the same forging technique.
Researchers at the University of Southampton evaluated the fossilized sea urchin trails from northern Spain and noticed that the tracks reflect a hunting pattern that infact, is still used by a vast variety of modern creatures. This is the first evidence that highlights the hunting strategy extinct animal's used for food that was short in supply.
The latest finding led by David Sims, Professor of Marine Ecology at the University of Southampton, offers clue into why most of the modern animals rely on same technique and suggests that this pattern may have a more ancient origin than previously beieved.
The study highlights the use of a random search strategy called the Levy walk that is used by creatures including sharks, honeybees, albatrosses and penguins to search for food. This movement consists of several small steps along with a few longer steps. Though it is defined as a random search strategy, it is known to be the most efficient method to hunt for food when there is scarcity of it.
"How best to search for food in complex landscapes is a common problem facing all mobile creatures. Finding food in a timely fashion can be a matter of life or death for animals -- choose the wrong direction to move in often enough and it could be curtains. But moving in a random search pattern called a Lévy walk is mathematically the best way to find isolated food," said Professor David Sims.
Till date, not much was known about the origin of the pattern despite knowing that it is a widely used searching technique among modern creatures.
In this study, a team of international researchers evaluated the fossilized Eocene-era tracks left by the sea urchins that thrived in the deep sea floor around 50 million years ago. The long trails were well preserved in the rocky cliffs of northern Spain called Zumaia. The Eocene era lasted from 56-33.9 million years ago and started when the planet began warming.
"Finding the signature of an optimal behavior in the fossil record is exceedingly rare and will help to understand how ancient animals survived very harsh conditions associated with the effects of dramatic climate changes," said Professor Sims, who is currently seconded to the Marine Biological Association in Plymouth. "Perhaps it's a case of when the going got tough, the tough really did get going."
The pattern identified is extremely intriguing as they indicate optimal Levy walk searchers have a very ancient origin and may have evolved from simple behaviors observed in older fossil trails from the Silurian period, some 440 million years ago.
Professor Richard Twitchett, of the Natural History Museum and co-author of the study, added: "It's amazing to think that 50 million-year-old fossil burrows and trails have provided us with the first evidence of foraging strategies in animals that live on and in the deep-sea floor -- studies which would be nearly impossible and very expensive to do in modern oceans."
The frozen fossil tracks reveal a lot on evolution of life on Earth and the environments that existed in the past. The researchers assume that it is the fall of the primary producers such as phytoplankton's and widespread scarcity due to mass extinction that gave rise to the evolution of the Levy-like searchers.
Surprisingly, Levy walks are not just confined to animals as the researcher's claims that even our ancient hunter-gatherer ancestors used the exactly same approach as modern hunter-gatherers in northern Tanzania.
The finding was documented in the Proceedings of the National Academy of Sciences.