More than 30 years ago, scientists sequenced the first genome—the genetic make-up—of a bacteria-infecting virus called bacteriophage Fx174. Since then, many people have heard of the popular Human Genome Project, which mapped the entire human genome, which consists of some 20,000 to 25,000 genes. In the meantime, scientists have sequenced thousands of wily and weird genomes of other organisms.

Genomes are most commonly sequenced in the process of researching a disease or a function of a particular organism, though sometimes, pure curiosity wins out. Sequencing is a costly enterprise (though it's gotten exponentially cheaper in the past 15 years), so securing funding is the first place researchers must begin. For projects paid for by the National Institutes of Health (NIH), which funds at least half of genome-sequencing research in the U.S., scientists must propose how this new genome will improve human health, expand a biological understanding, or have other positive implications. In other cases, private investors will fund research beneficial to their line of work or study. Here are a handful of some of the most unusual genomes sequenced by scientists.

1. NAKED MOLE RAT (HETEROCEPHALUS GLABER)

The naked mole rat is not known for its beauty. Entirely hairless, blind, and bearing sharp protruding teeth, it spends its entire life underground, never seeing the Sun. But it's an extraordinary animal: With a lifespan of about 30 years, it's the longest-lived rodent, and it's highly resistant to pain and diseases of aging such as strokes and cancer. Scientists are studying its genome to see if it explains the animal’s tolerance and longevity—and hopefully to translate what they've learned into human applications.

2. CALIFORNIA TWO-SPOT OCTOPUS (OCTOPUS BIMACULOIDES)

The genomic mapping of the octopus suggests they’re the closest thing on the planet to an alien that we’ve ever seen. With huge brains, three hearts, eight nerve-laden arms, taste buds, the ability to camouflage themselves, and neurons that allow their arms to "think" independently, they’ve demonstrated remarkable intelligence for an animal without a skeleton. Not only do they have as many genes as humans, the octopus has an extremely large number of "jumping" genes, called transposons, that can easily change their position in a protein chain, giving them an otherworldly intelligence. “It’s important for us to know the genome, because it gives us insights into how the sophisticated cognitive skills of octopuses evolved,” neurobiologist Benny Hochner from the Hebrew University of Jerusalem, who has studied octopus neurophysiology for two decades, told Nature. “Very simple molluscs like the clam—they just sit in the mud, filtering food. And then we have the magnificent octopus, which left its shell and developed the most-elaborate behaviors in water.”

3. BEER YEAST (SACCHAROMYCES CEREVISIAE)

Researchers at the California-based White Labs and a Belgian genetics laboratory have undertaken an experiment to sequence and compare the DNA of hundreds of yeast, many from genus Saccharomyces, for the sole purpose of brewing better, tastier beers. The researchers in the Belgian lab—a joint venture of the Flanders Institute for Biotechnology and the University of Leuven, Belgium—hope to use the information to create beers that don’t yet exist. “All this work," Troels Prahl, head of White Labs research and development, told Chemical & Engineering News, "is driven by the love of beer and the love of science.”

4. BODY LICE (PEDICULUS HUMANUS HUMANUS )

Just the word lice will make most people experience a shiver of revulsion and a psychosomatic itch. This hardy parasite is nobody’s friend, though it’s found on numerous animals and some humans. Scientists sequenced the genome of this miniscule parasite to better understand disease vectors; body lice can be a carrier of diseases such as epidemic typhus, relapsing fever, and trench fever. Unlike the host-dependent head lice, which requires its host’s warmth to survive, and is not a disease vector, body lice can survive independent of a host on clothing or surfaces for some time.

5. PLATYPUS (ORNITHORHYNCHUS ANATINUS)

The platypus was always one odd animal—with its duck-like beak and furry, mammalian body, the first scientists to see and handle a specimen thought it was fake. It has thick fur, and females, which lay eggs and have no nipples, produce milk for their young straight through the abdominal skin. Males platypuses are the only mammals that produce venom—a reptilian trait. So it's no wonder that everyone was curious about how this animal ended up the way it is. Genome sequencing has revealed its ancestry to be even more complex and unique than scientists had realized. It contains genes shared by mammals, birds, and reptiles all in one and appears to be the missing link in the evolutionary divergence of mammals from reptiles. While humans have but two sex chromosomes (x or y), the platypus has 10—five of each kind.

6. GREAT BARRIER REEF DEMOSPONGE (AMPHIMEDON QUEENSLANDICA)

The sea sponge barely qualifies as an animal, lacking a nervous system, gut, and other organs normally found in animals. Despite being more than 600 million years old, it has also evolved remarkably little; that’s because its genome suggests a more advanced creature on a cellular level than scientists previously thought. When scientists sequence the genome of the sea sponge Amphimedon queenslandica, they discovered that its genome provides crucial information on the origins of multicellular animals. "As the earliest branching lineage from our last common ancestor, sponges can tell us a lot about what is needed to make an animal," geneticist Mansi Srivastava told Nature. Sea sponges contain genes that support group cooperation of individual cells as well as cancer-related genes that suggest they, too, have had to fight off cancer, just like other animals.

7. FRUIT FLY (DROSOPHILA MELANOGASTER)

The fruit fly genome is one of the most studied genomes of all living creatures. This is because humans and fruit flies share about 75 percent of the same kinds of genes, making them ideal for research into human-related diseases. Scientists can also modify and re-engineer fruit fly genes and then study the effects for potential applications in human therapeutics. Because fruit flies live short lives, scientists can study multiple generations of their genes and modifications in a fraction of the time it would take to study generations of mice or human subjects.

All images courtesy of iStock