Art or Goo?: Beauty is in the eye of the beholder when it comes to jellyfish. With over 1,500 species in a myriad of colors and sizes, they can either be seen as floating pieces of colorful art (some even give a light show) or as blobs of goo capable of ruining a day at the beach.

Body Basics: Jellyfish start their lives as small polyps on the seabed. Eventually, dozens of medusae — free swimming forms — break off the polyps and begin their journey to sexual maturity. The body of a jellyfish is bell-shaped with a mouth on the underside. Tentacles of varying lengths extend below.

Following the Current: Jellyfish contract their fluid bodies to move, but are not very efficient swimmers. Instead, water currents usually determine their path and many find themselves washed up on beaches.

Poisonous Predators: Some species, such as the sea wasp, are poisonous. Most are carnivorous, but the lion's mane, one of the largest of the species, relies on algae for its food source.