Mammals generally have evolved the same basic, boring way for males to fertilize an egg: just send a bunch of tiny individual sperm into the female reproductive organs. But in insects like the diving beetle, it gets way more insane.
When we imagine great predators like bears, lions, sharks, and the T. rex, they're generally just chowing down on whatever hapless animal wanders in front of them. But if beetles are anything to go by, predators have a surprisingly nutritious diet.
Rove beetles have come up with a truly novel way to ensure monogamy. After a male has mated with a female, he injects her with a chemical that makes her smell so bad that all other prospective suitors stay away.
From a strictly evolutionary perspective, there's no reason why female beetles should be promiscuous. Unlike males, taking on multiple partners won't allow females to spread their genes more widely, and too much sex can actual shorten the female beetle lifespan.
The predator-prey relationship between frogs and beetles seems like it would be pretty obvious doesn't it? Frog spots beetle, frog stealthily approaches beetle, frog eats beetle. Done, done and done.
If seed beetles aren't careful, wasps will invade their eggs and have their own young kill the beetle larvae for nutrients. But these beetles aren't taking the threat lying down - they've developed an ingenious strategy to fight back.
In the normal course of things, beetles will generally stick to eating insects, worms, and any dead meat it happens to come across. But if conditions are right, one species will kill and devour frogs many times its own size.