Who Knew Cyanide and Vomit Could Be Such Great Gifts?

When we think of giving gifts on Valentine's Day, we immediately turn to the usual suspects: chocolates, flowers, jewelry, stuffed animals. These things are meant to symbolize our feelings of affection for one another. I've turned to the animal kingdom this year to get a glimpse at some more unusual forms of gift giving.

I found myself on this train of thought after remembering how my cat once left me a dead bird at my doorstep, and I thought it was her unique way of sharing her love with me. I later learned that that wasn't exactly the case, as cats do this to carry out their maternal instincts of training their young to hunt for food. Although being the recipient of a fresh kill from my cat was not exactly a gift but more of an introductory course to the methods of hunting, it still made me think: Do other members of the animal kingdom give each other gifts as a sign of affection? And what might be some of the most shocking types of gifts out there? As it turns out, many animals take part in this form of behavior. Termed "nuptial gifts," scientists have been hypothesizing the reasons behind this behavior since the mid-1970s. Many believe nuptial gifts increase the likelihood of successful mating between the male and his prospective female -- OK, so not necessarily a sign of affection, but a meaningful gift nonetheless.

Here are some interesting and truly bizarre nuptial gifts that our animal relatives use to woo their mates:

Nuptial gifts are very common among arthropods, especially among spiders. In South America there is a species of spider, Paratrechalea ornata, whose males present the females with a tasty meal wrapped in pheromone-clad silk as a way to entice the female to accept him as a mate. That isn't necessarily surprising, but apparently there are other species of spiders out there that have become quite sneaky in this game of love: They present silk-wrapped gifts laced with pheromones, but inside the silk is no meal at all -- nothing but perhaps a worthless twig or leaf. I'm not sure about you, but if I were the lady spider, this would definitely not fly.

Other arthropods, like insects, also partake in gift giving. Upping the ante with the bizarre level is the fruit fly species Drosophila subobscura. Now here is a gift that might make you a little queasy if you were on the receiving end: When a male fruit fly comes across a female that he has his eyes on, he throws up whatever is inside his stomach and offers it to the female as a source of nutrition. The more nutritious the vomit, the better his chances of winning his belle over. To them it is liquid gold. As for me, I'll settle for chocolate.

And I'm sure the last thing on your gift list this Valentine's Day is cyanide for your lover, but for the male Six-spot Burnet moth (Zygaena filipendulae), it's his go-to. These incredibly beautiful but toxic moths rely on cyanide as a means of defense, poisoning any poor creature that mistakes them for a scrumptious snack. When it comes to wooing a mate, the male offers cyanide to the female to help with her defense. This cyanide is also transferred from the female to her eggs, making one big happy -- yet lethal -- family. Now I understand what Britney Spears was singing about in "Toxic."

It's probably not a wise idea to take notes from these three, unless you want to send your counterpart running for the door. In addition to making this Valentine's Day all about romance, try exploring with that special someone a new area of science, from the chemistry of chocolate to the neuroscience of love.