An increasing number of the world's animals faces extinction risk but findings of a new research have revealed that the threat tends to be worst for the biggest and smallest creatures.

Biggest And Smallest Animals More At Risk Of Extinction

In a new study published in the journal Proceedings of the National Academy of Sciences on Tuesday, Sept. 19, researchers examined more than 27,000 vertebrate species based on their body mass. Of the species whose size data are available, researchers found that 17 percent face threats of extinction.

Studies on birds and mammals showed that animals with larger bodies are more likely to face extinction, but the new study revealed that animals on the small ends of the scale face similar threats as well.

"Surprisingly, we found that not only the largest of all vertebrate animal species are most threatened, but the very tiniest ones are also highly threatened with extinction," said study researcher Bill Ripple of Oregon State University.

"I think, for the smallest species, first of all we need to bring higher awareness to them, because the larger ones get a lot of attention, but the smaller ones get very little."

Non-Mammals Overlooked By Protection Efforts

The research, which evaluated birds, reptiles, mammals, amphibians, bony fishes, and cartilaginous fishes (such as sharks and rays), also revealed that there are species overlooked in terms of conservation efforts.

Big and well-known mammals such as rhinos, whales, elephants and lions, have long been the targets of protection efforts but other large-bodied non-mammal animals such as the Somali ostrich, Komodo dragon, whale sharks, and the Atlantic sturgeon also need conservation efforts.

Researchers said that different conservation strategies are needed to address the threats posed to the largest and smallest of animals.

Threats Faced By Large And Small Animals

The heavyweights are primarily threatened by hunting, while the featherweights are threatened by logging and pollution. Researchers said that the smallest creatures tend to have restricted geographic ranges, considered to be a crucial factor that can predict extinction risk, making the smallest species vulnerable to the effects of habitat degradation.

"Our results offer insight into halting the ongoing wave of vertebrate extinctions by revealing the vulnerability of large and small taxa, and identifying size-specific threats," the researchers wrote in their study.

"Without intervention, anthropogenic activities will soon precipitate a double truncation of the size distribution of the world's vertebrates, fundamentally reordering the structure of life on our planet."