This time of year, many creepy crawlies take center stage to frighten people of all ages. To celebrate Halloween, we've conjured up a slideshow of fascinating but spooky species that NIGMS-funded scientists study. Some of these creatures drink blood like vampires, while others—frogs, worms, flies, and salamanders—are perfect cauldron ingredients for a witch's brew. Check out the slideshow—if you dare!

Relationships are complicated, even in nature. Two unrelated species living close together and interacting for survival is called symbiosis. There are three types of symbiotic relationships: mutualism, commensalism, and parasitism.

In a mutualistic relationship, both organisms benefit from the interaction. One example is the relationship between honeybees and flowers. Honeybees drink nectar from flowers, collecting and carrying pollen as they fly from one flower to another. Nectar allows bees to make honey, and spreading pollen helps flowers reproduce. Another example of a mutualistic relationship is between clownfish and sea anemones. The sea anemone provides protection and shelter, while clownfish waste provides the sea anemone with nutrients.

RNA is essential for life as we know it. Among other roles, this molecule helps translate the instructions of DNA into proteins, which perform a vast range of tasks to keep us alive and healthy. In past Biomedical Beat posts, we've discussed the basics of RNA and how researchers are using it to develop medicines, vaccines, and tests for certain diseases. This year, in honor of RNA Day on August 1, we've created a quiz all about this remarkable molecule. Test your knowledge with the questions below!

Hormones are chemical messengers in the body that glands form and release, or secrete, into the bloodstream, where they travel to various organs and tissues to change biological functions. Hormone levels fluctuate during a lifespan and even on a daily basis.

Growth spurts in toddlers or sudden changes in adolescents are directly related to large hormonal shifts during development and puberty. Smaller changes occur throughout each day to help maintain normal bodily functions, such as our sleep-wake cycle known as our circadian rhythm.