How do color-blind cephalopods — octopus, squid and others — achieve such a good color match when they camouflage? (in short: amazing, distributed brains). And what does it take to study these elusive animals in the wild? (a whole lot of patience). Marine scientist Roger Hanlon dives deeper into his research.

You won’t see these amazing animals on a day at the beach, but they’re there — living in the vast, cold, unexplored midwater region of the ocean. Learn about six of its residents and how they’ve adapted to life in the dark.

A flying device combined with some nifty software is serving up invaluable information about the health of whales — and our oceans.

These weird-looking, isolated aquatic creatures probably won’t star in a Pixar film anytime soon, but by studying them, we can learn about our planet’s past and its future, says evolutionary biologist and ichthyologist Prosanta Chakrabarty.

Bigeye at Rapture Reef, a part of the Northwestern Hawaiian Islands Marine National Monument. Within this marine protected area, fish species can rebound. Photo by the NOAA National Ocean Service.

Given climate change, coral bleaching, ocean acidification and overfishing, it can be easy to feel depressed about our oceans. But when you look at the big picture of ocean health, good news emerges.

Each year in September, corals in the Caribbean stage a mass spawning event. Witnessing it, says marine biologist and TED Fellow Kristen Marhaver, is like swimming inside a snow globe. Here, she explains how corals beget corals — and how she and her fellow scientists are trying to help them along.

Marine biologist Stephen Palumbi picks 10 of his favorite underwater creatures. From the oldest living animal to the fastest food in the sea, they’re all pretty extreme.