Animal Mysteries

Noun highly poisonous metallic element (commonly brittle, crystalline gray)
The newly discovered microbe known as strain GFAJ-1 grows when fed arsenic and deprived of phosphate, a crucial ingredient of life.
Verb prove too difficult or complicated for somebody to understand
Around 2 million fish have died in the Chesapeake Bay area in Maryland, just days after two similar incidents elsewhere in the US baffled scientists.
Verb select or gather, especially those that are good examples of their kind
Scientists have concluded that culling bat populations will not stop white-nose syndrome, a fungal pathogen that is wiping out the species, from spreading.
Adjective quiet and unlikely to cause trouble
Huge, docile whale sharks live in oceans around the world, but no one knows where they breed, their migration routes, or even how many there are.
Adjective strange and frightening
"It's eerie that his eye hasn't started to decay. He looks like he's just lying back on the asphalt with red eyeliner on." (karenstock comment)
Adjective being effective without wasting time or effort
The Great White, one of the most feared predators on earth, is an incredibly efficient hunter. Scientists have yet to understand the drive behind their feeding behavior.
Noun rapid increase in number
The rose-ringed parakeet is procreating with great success in London suburbs, leaving the British amazed and annoyed by their proliferation.
Adjective withdrawn from the rest of the world
Discovered only in 2003, the Purple Frog's reclusive lifestyle is what caused the species to escape earlier notice by biologists.
Noun careful observation or examination, especially in a critical way
Coyotes have managed to elude much serious scrutiny by being exquisitely wary, so much so that even dedicated coyote scientists struggle to find ways to lay eyes on them.
Verb believe especially on uncertain grounds
Scientists speculate the giant predators may have engaged in cannibalism with some regularity.