Eels Alive!

To qualify as a true eel, a creature must belong to the order Anguilliformes, which includes 20 families, 111 genera, and over 800 species. These remarkable fish range from just four inches to massive 12-foot moray eels. What sets them apart is their distinctive worm-like bodies, lack of pelvic fins, and the ability to swim both forward and backward by simply reversing their wave-like motion.

• Eels belong to order Anguilliformes with over 800 species ranging from 4 inches to 12 feet long
• Eels have long worm-like bodies, no pelvic fins, and move through water in a wave-like slithering motion
• Eels can swim backward by reversing the direction of their wave motion (and make beeping sounds when they do)
• Eels are coated in protective slime that helps with swimming and regulates water in their bodies
• Eels contain magnetite in their heads which likely helps them navigate using Earth's magnetic fields

Moray eels are perhaps the most famous saltwater eels, making up about 25% of all eel species with 200 varieties across 15 genera. These predatory fish are known for their intimidating appearance, particularly their visible teeth and constant mouth-gaping, which is actually just their way of breathing rather than aggressive posturing. They spend their days hiding in coral reef crevices and hunt primarily at night.

• Moray eels represent about 25% of all eel species with 200 types in the Muranidae family
• Morays lack opercula (gill covers), so they must constantly open their mouths to move water over their gills
• Moray eels have two sets of jaws, with a pharyngeal jaw that faces backward to lock prey in place
• While moray bites are painful and prone to infection, they're not venomous - the slime contains hemagglutinin that clumps red blood cells