at a reduced volume and further reducing the volume of their clicks as they close in on prey moths. The lower volume of clicks reduces the effective successful hunting range, but results in a significantly higher number of moths caught than other, louder bat species. Moths have further evolved the ability to discriminate between high and low echolocation click rates, which indicates whether the bat has just detected their presence or is actively pursuing them. This allows them to decide whether or not defensive ultrasonic clicks are worth the time and energy expenditure. The rough-skinned newt and the common garter snake Rough-skinned newts have skin glands that contain a powerful nerve poison, tetrodotoxin, as an anti-predator adaptation. Throughout much of the newt's range, the common garter snake is resistant to the toxin. While in principle the toxin binds to a tube-shaped protein that acts as a sodium channel in the snake's nerve cells, a mutation in several snake populations configures the protein in such a way as to hamper or prevent binding of the toxin, conferring resistance. In turn, resistance creates a selective pressure that favors newts that produce more toxin. That in its turn imposes a selective pressure favoring snakes with mutations conferring even greater resistance. This evolutionary arms race has resulted in the newts producing levels of toxin far in excess of that needed to kill any other predator. In populations where garter snakes and newts live together, higher levels of tetrodotoxin and resistance to it are observed in the two species respectively. Where the species are separated, the toxin levels and resistance are lower. While isolated garter snakes have lower resistance, they still demonstrate an ability to resist low levels of the toxin, suggesting an ancestral predisposition to tetrodotoxin resistance. The lower levels of resistance in separated populations suggest a fitness cost of both toxin production and resistance. Snakes with high levels of tetrodotoxin resistance crawl more slowly than isolated populations of snakes, making them more vulnerable to predation. The same pattern is seen in isolated populations of newts, which have less toxin in their skin. There are geographic hotspots where levels of tetrodotoxin and resistance are extremely high, showing a close interaction between newts and snakes. Predator whelk and the hard-shelled bivalve prey The whelk predators used their own shell to open the shell of their prey, oftentimes breaking both shells of the predator and prey