Marine predators: Bigger in size with an appetite to match

June 15, 2017

The size of marine invertebrate predators has increased over the past 500 million years, while the size of their prey has not, a new study reveals. The results support a popular hypothesis that has been difficult to confirm. The so-called "escalation hypothesis" suggests that top-down pressure from increasingly powerful and metabolically active predators has driven evolutionary trends in prey; for example, by increasing their motility, burrowing, or defensive arsenal. Yet, reconstructing the ancient, complex interactions among predator and prey species, to gather insights into the likelihood of the escalation hypothesis, has been challenging. Here, Adiël A. Klompmaker and colleagues reconstructed predator-prey interactions of marine organisms in the Phanerozoic period, which spans the past 540 million years, by analyzing attack marks, or "drill holes," in the fossilized shells of various types of marine prey. First, they compared the sizes of hundreds of drill holes to the sizes of predators, confirming drill hole size increased as predator size did. Then they examined Phanerozoic trends in drill-hole size, prey size, and predator-prey size ratios across nearly 7,000 specimens, representing more than 360 taxa. While the median shell size of prey remained more or less constant over the course of a vast portion of the Phanerozoic period, the median drill-hole diameter increased from 0.35 to 3.25 millimeters, indicating a significant increase in the size of predators relative to their prey. The authors propose that the increase in the predator-prey size ratio is driven by dramatic changes in the energetic structure of marine ecosystems, where marine predators had to consume more prey in order to satisfy their ever-growing body size and appetites. Coinciding with this increase in predator size is a shift towards prey that are more mobile and better at burrowing, an effect that is consistent with predator-driven evolution, the authors say.
-end-


American Association for the Advancement of Science

Related Predators Articles from Brightsurf:

Boo! How do mexican cavefish escape predators?
When startled, do all fish respond the same way? A few fish, like Mexican cavefish, have evolved in unique environments without any predators.

Herbivores, not predators, most at risk of extinction
One million years ago, the extinction of large-bodied plant-eaters changed the trajectory of life on Earth.

Bugs resort to several colours to protect themselves from predators
New research has revealed for the first time that shield bugs use a variety of colours throughout their lives to avoid predators.

Jellyfish contain no calories, so why do they still attract predators?
New study shows that jellyfish are an important food source for many animals.

'Matador' guppies trick predators
Trinidadian guppies behave like matadors, focusing a predator's point of attack before dodging away at the last moment, new research shows.

The European viper uses cloak-and-dazzle to escape predators
Research of the University of Jyväskylä demonstrates that the characteristic zig-zag pattern on a viper's back performs opposing functions during a predation event.

Predators help prey adapt to an uncertain future
What effect does extinction of species have on the evolution of surviving species?

To warn or to hide from predators?: New computer simulation provides answers
Some toxic animals are bright to warn predators from attacking them, and some hide the warning colors, showing them only at the very last moment when they are about to be attacked.

Dragonflies are efficient predators
A study led by the University of Turku, Finland, has found that small, fiercely predatory damselflies catch and eat hundreds of thousands of insects during a single summer -- in an area surrounding just a single pond.

Predators to spare
In 2014, a disease of epidemic proportions gripped the West Coast of the US.

Read More: Predators News and Predators Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.