May 22

On May 22nd 2012, countries from around the world will celebrate International Day for Biological Diversity (IDB), an annual event aimed at increasing our understanding and awareness of the world’s biodiversity.

A Marine Theme

This year’s theme – ‘Marine Biodiversity’ – provides a fantastic opportunity to raise global awareness of the many issues facing the world’s marine ecosystems, and to encourage practical action to protect and conserve them.

From tropical oceans and coral reefs, to deep-sea vents and the ice-strewn waters of the Arctic and Antarctic, marine ecosystems are hugely diverse. Current estimates of the total number of known marine species range from 250,000 to at least a million, with some scientists believing that the actual figure could be twice as high.

With life in the oceans so incredibly diverse, picking out even a handful of our favourite marine images poses a tough challenge, but we’ve dipped into our ocean imagery to share some of our biggest catches…

Whale shark

Photo of whale shark filter feeding surrounded by other smaller fish

The whale shark is the world’s largest fish, growing up to a staggering 12 metres long and weighing around 12,500 kilograms. Despite their huge size, whale sharks feed almost entirely by filter-feeding on plankton and small fish.

Loggerhead turtle

Photo of loggerhead turtle swimming with a shoal of pilot fish

One of the most widespread of all the marine turtles, the loggerhead turtle is also the most highly migratory, with some individuals having been known to cross the Atlantic and Pacific Oceans.


Photo of nautilus swimming

Nautiluses are often considered “living fossils”, having survived relatively unchanged for millions of years. They are found only in the Indo-Pacific Ocean, where they inhabit the deep slopes of coral reefs.

Blue rice coral

Blue rice coral in shallow reef

The blue rice coral is endemic to Hawaii. Like many other reef-building corals, the blue rice coral is threatened by factors such as bleaching caused by rising sea temperatures, as well as by disease, destructive fishing methods and invasive species.

Sea Otter

Photo of Alaskan sea otter pup eating shellfish

The smallest marine mammal in the world, the adorable sea otter relies on its fur to keep warm in the water. The sea otter’s coat is the densest of any mammal, consisting of around 100,000 hairs per cm²!

Find out more about the International Day for Biodiversity and discover what’s being done to celebrate IDB 2012 in your country.

Explore more marine species on ARKive.

Helen Roddis, ARKive Species Text Author

  • Dmitri (May 22nd, 2012 at 2:37 pm):

    Nice, but I thought that the smallest sea mammal in the world was the sea otter’s cousin, the marine otter (a.k.a the feline otter) instead. But, I may be wrong. (And probably I am.)

  • abhimanyu Singh (May 22nd, 2012 at 6:21 pm):

    Wonderful amazing Photography and information

  • Lair (May 22nd, 2012 at 8:59 pm):

    Ecrivez moi en français s’IL VOUS PLAIT

  • Aldina (May 23rd, 2012 at 8:06 am):

    Really, really wanderful pictures!

    I live in Croatia on an wanderful island. My favorite sport is snorkeling. During the summer I have a traditional daily route and is interesting when you meet every day the same fishes on same positions!

    Unfortunately, I have never met such wanderful animals, but our are interesting too.

    Thank you for this wanderful beginning of the day!