Blue Planet: Diversity Beneath the Waves

Take a breath. Now take another: you could say that the oxygen in one of those two breaths was produced by green plants on land, the oxygen in the other by floating phytoplankton in the oceans.
Life in the oceans has sustained human civilization and development for millennia, from providing food and nourishment, material for handicraft and construction, to the very air we breathe. Today, about half of the oxygen in Earth’s atmosphere is produced in the ocean, every second breath we take. Before the evolution of land plants 400 Million years ago, for billions of years all oxygen in the atmosphere was produced by microscopic phytoplankton.


This showcase of seashells in our Tree of Life exhibit in the Science Library demonstrates the success of different body plans in this group of animals. Mollusks include some of the most intelligent invertebrates on the planet, such as the octopus, as wells a clams which have no brain. Snails are the only group of mollusks which evolved a terrestrial lifestyle; cephalopods are exclusively marine, and bivalves are exclusively aquatic.


Seashells are amongst the most diverse animal group in the oceans. These drawers in a cabinet the Joe Webb Peoples museum contain some 5500 fossil seashells from the Pliocene deposits in Sarasota County, Florida. After 4 million years, they are no longer as colorful as shells on the beach today, but they remain important markers of diversity over time, and can be used to document changes in marine life with changing climate.


For the very first time, on March 3rd, 2019, the United Nations Development Program World Wildlife Day unites the world in honoring the natural heritage of biodiversity in the oceans. Themed Life Below Water: For People & Planet, the celebration aims to highlight critical issues surrounding the fragile beauty of our oceans, and the dire need to increase our collective efforts to conserve the complexity that typifies their inherent beauty.


Hermit crabs (Pagurus sp.) and their shells have been well preserved in alcohol for over a century in the Wesleyan Natural History Collections. Hermit crabs are little marvels of evolution, having adopted a lifestyle that is possible only because they evolved alongside sea snails, whose discarded shells they use.


Arthropods, a Phylum which which includes insects, are the most diverse animals on land today. In the oceans they are also extremely diverse and can assume unusual shapes. The mole crab (Hippa sp.) to the right looks like a regular crustacean, while the goose barnacle to the back (Pedunculata) looks nothing like a bug. Barnacles have been described as animals that stand on their heads and kick food into their mouths.


The Wesleyan Natural History Collections house a vast number of marine specimens, forms which were alive or only just dead when collected in the 19th Century, and fossils, many dating back hundreds of millions of years. In fact, the majority of our collections consists of marine organisms, including sponges, corals, molluscan seashells, brachiopods, bryozoans, star fish, worms, fish, marine mammals and many moreAmong these, the seashells make up a major part of the collection, numbering some tens of thousands, many of which were acquired before  the opening of the former Wesleyan Museum in Judd Hall, with a large purchase of some 9,000 seashells from the Shurtleff Collection in 1868.


What truly epitomizes the expansive marine life collections  are the brachiopod collections. Numbering in the 30, 000s, we have been attempting to complete digitizing the information on these animals for more than a year. Most of them will never be publicly exhibited since they often look like pavement gravel, but they are rich in information that scientists can use to understand critical issues of today, such as climate change and mass extinctions.


Our wet collection includes over 300 specimens from 21 Phyla. Most marine animals in these jar of alcohol are assorted worms.
All life evolved beneath the waves. In fact, it took 3 billion years after the  first life forms evolved on Earth for the first animals and plants to start moving onto land. During the largest diversification event in Earth’s history, the Cambrian Explosion, ~541 million years ago, all known past and present major groups (Phyla) of animals had already originated. Some animals adopted a terrestrial lifestyle, such as arthropods, mollusks, and chordates – which includes us – and many worms. Others remained exclusively marine, such as star fish and sea urchins, jellyfish and corals. All major groups of animals are represented below the waves, where many more Phyla of animals live than there are on land.


Our basket star is a bizarre looking oddity preserved in alcohol. It belongs to the echinoderms, a group with five-sided symmetry (as seen above), which includes star fish, sea urchins, sea lilies and sea cucumbers. Echinoderms are exclusively marine.


Abdoulaye Mar Dieye, UN Assistant Secretary General and Director of UNDP’s Bureau for Policy and Programme Support notes, “Oceans regulate our climate, produce half the oxygen we breathe, provide nourishment for 3+ billion people, and absorb 30% of carbon dioxide released into the atmosphere and fully 90% of the heat from climate change. To ensure that oceans and marine species are preserved and protected, nature-based solutions that bring together public, private and civil society partners need to be replicated and scaled-up.”


Ichthyosaurus communis, replica of a specimen found by Mary Anning on the coast of Lyme-Regis in Southern England. Our rich collections include many sea monsters like this extinct marine reptile, which lived in the Jurassic period when dinosaurs roamed on land (~ 150 million years ago), a key piece of evidence used in the 1800s to establish that extinction had actually occurred.


One of our most treasured specimens is this heteromorph ammonite from the Pierre Shale Formation, dating back to the Cretaceous, when a large part of what is now the Great Plains in the United States was covered by the Western Interior Seaway, at some time reaching from what is now the Gulf of Mexico to what is now the Arctic Ocean. The Pierre Shale is the host formation for commercial oil and gas deposits in Colorado. The ammonites which whom we are most familiar have a spiral form, but many evolved grotesque shapes like a hairpin, or random globs like this one.


The mysteries of the oceans have captivated the imagination of humans since antiquity, with many accounts of mythical creatures, some fictitious and others real – or slightly exaggerated – animals, filled our literary and artistic inspiration. The depths of the oceans are the world’s largest habitat. With technological advances, including remotely operated vehicles, underwater drones, and sensors mounted on marine animals, the unexplored depths of the oceans have become the new frontier of scientific surveys.