The Ocean Species You Never Knew You Needed

Today is the U.N.'s annual International Day of Biological Diversity, an observance meant to raise awareness about the importance of -- and threats to -- the world's species. This year's theme, island biodiversity, calls attention to the astounding, unique marine life that often congregates around oceanic islands, which are also home to one-tenth of all people on Earth.

In fact, marine species play innumerable roles that underpin all of our welfare, whether you live near or far from the sea. Scott Henderson, vice president of Conservation International's Eastern Tropical Pacific Seascape program, shares a few that might surprise you.

1. Tuna

These streamlined, lightning-fast swimmers not only underpin the food and livelihood security of millions of people -- they also act as top ocean predators that keep species populations in check to ensure a healthy balance between different levels in the food web. Drastic tuna population declines would likely have negative impacts on ocean health.

2. Krill

Practically at the opposite end of the size spectrum from tuna, which can attain gigantic proportions, billions of tiny krill -- small oceanic shrimp-like creatures -- serve as the foundation of food chains, especially in the southern oceans.

3. Mangroves

Forming stately forests that cover hundreds of unbroken miles of coastline in some areas, mangroves provide coastal societies with protection from extreme weather events and serve as nursery areas for many species, including fish that are important for both local food security and national revenues.

4. Diatoms

These single-celled, glass covered, free-floating (planktonic) organisms are the most abundant marine species on Earth and sustain the majority of the ocean's productivity. Without them serving as vast quantities of food for everything else, there would be few more complex life forms. Additionally, diatoms produce much of the oxygen we need.

Read the full post on Conservation International's blog, Human Nature.