By Scott Henderson for Conservation International
Life on Earth is old. Fossil records indicate that the first simple organisms emerged about 3.8 billion years ago, and it took another 1.8 billion years for multicelled organisms to evolve. Life is also extremely diverse.
Best estimates put the current number of multicelled species on Earth at about 10 million — probably the greatest number of species that has ever inhabited our planet at a given time.
Extinction is not a new phenomenon; experts estimate that over the Earth’s history, natural causes ranging from competition between species to natural disasters have led to the extinction of about 10 species per year. However, Earth’s biodiversity is now being lost at an unprecedented rate as over 7 billion humans struggle to survive and thrive.
With human-generated pressures from habitat loss, targeted extraction and the impacts of invasive species, best estimates put the current extinction rate between 10 and 100 times higher. Clearly that’s bad news for the extinguished species and the environment they collectively hold together in a complex web of life. It’s also bad for us.
In order to raise awareness about the benefits of nature and the threats that drive extinctions, the United Nations has proclaimed May 22 as the annual International Day for Biological Diversity. This year’s theme is marine biodiversity.
Marine species play innumerable roles that underpin our welfare. Some of these are obvious, but others less so. Following is a selection of just a few marine species and the roles they play in our lives.
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.
Discover the other species by continuing to read the article at http://blog.conservation.org/2012/05/9-ocean-species-you-never-knew-you-needed/