We humans like to explore the world, but sometimes we even find surprises in our own bodies.

Take the mesentery, a membrane that attaches the intestine to the abdominal wall. A new study claims the mesentery should be considered an organ unto itself rather than disparate parts.

The revelation made Weird Animal Question of the Week wonder: “What organs do other animals have that we humans don’t?”

The more we looked, the more jealous we got.

Photophores

These are light-producing organs that give some fish bioluminescence. Marine biologist Edie Widder, founder of the Ocean Research and Conservation Association, has a favorite: The smalltooth dragonfish, Pachystomias microdon.

This deep-sea denizen has three "flashlights" under its eyes: one red, one orange, and one blue.

Most ocean dwellers can see blue light, which Widder calls “the high beams,” but few can see red light.

So the dragonfish uses its red light as a “sniper scope” to see unsuspecting prey or to carry out “private conversation” during courtship.

The purpose of the orange light is still a mystery, Widder says.

Still, portable mood lighting? Smoothest move ever.

Mental Glands

Despite their name, these pheromone-delivering glands have nothing to do with the mind “other than salamanders being crazy in love,” says Whit Gibbons, retired evolutionary biologist at the University of Georgia’s Savannah River Ecology Laboratory.

The name actually comes from the Latin mentum, meaning chin, which is where the gland is located in the male lungless salamander.

We won’t say “love stinks,” but for some species its definitely aromatic.

View Images You wouldn't want to mess with a side-striped palm viper (Bothriechis lateralis)—these creatures have venom glands and heat-sensing pits that help them see prey in the dark. Photograph by Survivalphotos, Alamy

Venom Glands and Heat Sensors

Pit vipers, which live through most of the Americas and Eurasia, double down on organs we lack, including venom glands and a heat-sensing pit in the face between the nostril and the eye.

These namesake pits detect infrared radiation, thus helping them sense prey in darkness from as close as two feet away, Gibbons says.

This killer instinct put the reptiles ahead of The Terminator “by a few million years,” Gibbons quips.

Bursa Copulatrix

This stomach-like organ is located in the reproductive tract of female butterflies.

The bursa copulatrix digests nutrients in the spermatophore, a packet of sperm given by the male during mating.

Bidder’s Organs

Most toads, male and female, have this “rudimentary ovary,” Gibbons says. If a male toad's testes are removed, its bidder's organ will grow bigger, and at one time it was thought to be a potential backup reproductive strategy. They also grow when testosterone is low.

Even so, its purpose remains elusive.

View Images A scientist displays the clasper, or penis-like organ, of a bigeye houndshark (Iago omanensis). Photograph by Jeff Rotman, Alamy

Claspers

Claspers are penis-like organs male sharks use to transfer seminal fluid into the vent of a female. In some species, the claspers are held in place by spiny projections.

Claspers can also refer to appendages some male insects use to hold females in place during copulation. Male dragonflies, for example, have sharp claspers at the tip of their segmented bodies that fit into the back of the female’s head during mating. (Read more about dragonflies' strange sex habits.)

Doesn’t it make you glad to be a human?