By Stuart Pimm
Biscayne National Park, Florida–There’s a distinct air of competition at a bioblitz. We’re all here to identify as many species as we can in 24 hours. We know how well our colleagues have done in the previous three efforts. We can do better.
I listen to the opening talks and keep one eye on the sky. I’m a birder. This is peak migration season. Here on the Florida coast, every migrant bird in eastern North America can pass over each spring, returning from wintering grounds in Central and South America.
I’ve got a list. And it’s increasing every few minutes.
But Sylvia Earle, National Geographic Explorer in Residence, is telling the crowd that biodiversity is not just a list. Were it so, then the tropical moist forests that I care about so much, beat the oceans hands down.
Sylvia’s point is that the ocean may have fewer species, but they are altogether more different from each other than what we find on land.
Now, I must tell you I watched the movie Avatar twice. I watched it once as a movie.
I watched it the second time–and will watch it more times–as a zoologist. It was in zoology that I got my undergraduate degree. And I’ll need some marine zoologists friends to help me. Some palaeontologists, too, but that’s another story.
As wonderful as the movie is, the natural world is full of the most extraordinary creations. And Sylvia’s point is that the oceans have a wider range of seemingly impossible body plans than does the land. Some are large and familiar–the superb hunting machine that is the shark, or manta rays that fly through the water. And fish–particularly the ones of the depths with hideous teeth and strange lanterns to lure their prey.
There are not merely lots of good fish in the sea, but many that not even Hollywood could conjure from the depths and make us believe.
Sylvia’s point is not really about fish. It’s about the major groups of animals that we call phyla–plural of phylum. All fish–and birds and mammals and reptiles and amphibians–are vertebrates. And vertebrates are the most familiar members of the phylum that are the animals with backbones. Vertebrates occur on land and in the sea, of course.
Variety of body plans
There are several phyla, however, that occur either only in the ocean–or else achieve by far their greatest variety of body plans there. And thats her point.
For example, one phylum is the annelids–the segmented worms. “Ugh,” you say and, on land, perhaps only a zoologist can love an earthworm or a leech. (Both are important, incidentally, but I share your lack of enthusiasm.)
Snorkeling off a coral reef, you’ll find the lovely fan worms–beautifully colored, but shy–withdrawing into their tubes at the slightest disturbance. They are among the first alien forms encountered on planet Pandora in the movie–albeit on land and hundreds of times larger. They too are annelids, but a group found only in the ocean.
You probably don’t think much of slugs and snails either. Some marine snails have elegantly crafted shells, of course.
Today, I saw a snail fly by.
Today, I saw a snail fly by.
Yes, you read that correctly.
To find my flying snail–it’s called a pteropod–”wing foot”–yes, it’s flying with its feet–I boarded the boat this morning to do a plankton trawl.
Along with an enthusiastic group of school-age bioblitzers, we ventured forth into the bay off the visitor centre. As soon as we were in deep water, National Park biologist Richard Curry put a fine net over the side. Twenty minutes later, the net with its “cod end”–a small bottle to catch the plankton–is hauled back on ship and the contents emptied into a dish.
We’ve got a bottle of plankton–the tiny plants and animals that drift in the ocean.
There’s my flying snail. OK. It’s flying in the water, flapping it’s wings like a butterfly and it’s only a two tenths of an inch long. Under the microscope, it’s exquisite. It belongs in a movie.
When we get back to the tent, two graduate students from Florida International University, Nitzan Soffer and Rory Welsh are my guides to what we’ve found.
There are two kinds of plankton: phytoplankton–plants–and zooplankton. They are extraordinarily diverse. Some are very tiny fish, just hatched from eggs. There’s a very tiny puffer fish and a pipe fish, all just a fraction of an inch long.
Smaller than even these, is the wide variety of tiny creatures each with different body shapes and feeding strategies as wonderful as the flying snail.
The students who crowd around the microscopes in the inventory tent get the message. In a bottle of seawater from a plankton tow, is an entire world at least as strange as the fictional planet of Pandora, and within the sight of downtown Miami.
Professor Stuart L. Pimm is a conservation biologist at Duke University, North Carolina. A former member of the National Geographic Committee for Research and Exploration, Pimm is the author of dozens of books and research papers, including the book “The World According to Pimm: A Scientist Audits the Earth.”