Saturday, August 1, 2009

Sea Slugs & Ships: Memory & Biodiversity.

Yunnan China ©2008 Am ang Zhang

In a trip back to my birthplace Yunnan of China, I met a “bright young thing” with a camera that has a longer lens than mine. In conversation, she told me she was studying Biodiversity.

Kandel’s research of the sea slug species Aplysia won him the Nobel Prize. The Aplysia was picked because its nervous system was relatively easy to study. Aplysia and its cousin Nudibranch may indeed hold more than the secret of our memory. Recent works showed that some of the chemicals these creatures of the ocean carry may be useful for marine coating as molluscs do not like it.

As you board your next cruise ship spare some thought for the little Aplysia.

©2006 Am ang Zhang

The ultimate in underwater activity is diving, as divers can reach depths that the snorkeler cannot and therefore see a whole different world. I am therefore grateful to my good friend Irene for allowing me to show some of her amazing diving photos here.

Manta Ray © 2009 Irene Man

Small creatures can be as fascinating as the larger ones:

Nudibranch © 2009 Irene Man

Nudibranch is so named because of its naked gills.

Here is a description in The National Geographic:

“Nudibranchs crawl through life as slick and naked as a newborn. Snail kin whose ancestors shrugged off the shell millions of years ago, they are just skin, muscle, and organs sliding on trails of slime across ocean floors and coral heads the world over.

Nudibranch © 2009 Irene Man

“So why, in habitats swirling with voracious eaters, aren't nudibranchs picked off like shrimp at a barbecue? The 3,000-plus known nudibranch species, it turns out, are well equipped to defend themselves. Not only can they be tough-skinned, bumpy, and abrasive, but they've also traded the family shell for less burdensome weaponry: toxic secretions and stinging cells.”

These creatures are highly efficient in deploying poison:

“A few make their own poisons, but most pilfer from the foods they eat. Species that dine on toxic sponges, for example, alter and store the irritating compounds in their bodies and secrete them from skin cells or glands when disturbed. Other nudibranchs hoard capsules of tightly coiled stingers, called nematocysts, ingested from fire corals, anemones, and hydroids. Immune to the sting, the slugs deploy the stolen artillery along their own extremities.”

“Humans have also studied sea slugs' simple nervous systems for clues to learning and memory and have raided their chemical armory in search of pharmaceuticals. Scientists today are isolating chemicals that may help ailing heart, bone, and brain.

“Still, nudibranchs have hardly given up all their secrets. Scientists estimate that they've identified only half of all nudibranch species, and even the known ones are elusive. Most live no more than a year and then disappear without a trace, their boneless, shell-less bodies leaving no record of their brief, brilliant lives.”

The next generation of “bright young things” who do not wish to pursue medicine (or finance!) might do well to consider Biodiversity. They will have the legitimate excuse to do some diving too.

Links: National Geographic, Gallery

Emergiblog: A Cracking Grand Rounds!

Autobiography: Eric Kandel

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