I recently had the opportunity to visit the Monterey Bay Aquarium, one of my favorite places along California's Central Coast and certainly one of the world's pre-eminent aquaria. Monterey Bay Aquarium opened in 1984 - it will celebrate its 30th anniversary on October 20th. It is located on Monterey's famous Cannery Row (you may have read the book so titled by John Steinbeck, a native of nearby Salinas).
The aquarium's site was once the Hovden Cannery, which opened in 1916 and closed in 1973, when the sardine fishery in Monterey collapsed. About four years later, a group of marine scientists and area residents envisioned an aquarium where the Hovden Cannery had once been, and in 1978 the Monterey Bay Aquarium Foundation was formed with the support and financial assistance of the David and Lucile Packard Foundation, which made a one-time gift of $55 million dollars so that the aquarium could be constructed.
Photos courtesy Monterey Bay Aquarium
Sardines by the thousands
On any given day, the Monterey Bay Aquarium is a busy place, packed with people. And while I always marvel at seeing the denizens of the oceans, I am also delighted to see the wide-eyed, enthusiasm and wonder of the throngs of children. I would venture a guess, that on the Sunday we were there, there were 1,000 times more questions being floated than there were sardines swimming in the exhibits (and, boy, were there A LOT of sardines). The aquarium currently houses some 35,000 marine animals representing 500 species. There are 34 major galleries augmented in any given month by several special exhibits which, luckily for me because I am fascinated by them, included The Jellies Experience the day I was visiting.
Jellies come in a multitude of shapes and colors. Many are iridescent. Most are saltwater creatures, but there are freshwater varieties as well. They are found in every ocean - even in the Arctic and Antarctic. Some float on or near the surface while others have been found at depths of nearly 10,000 feet. It is surmised that their range extends to the ocean floor, which for a point of reference has been measured at 36,070 feet below sea level in the Mariana Trench near Guam.
Jellies are often referred to as jellyfish, but they are not fish. They are properly called medusae - a name that is believed to have been given by early scientists because jellies' tentacles evoked images of the writhing snakes on the head of the Medusa in Greek mythology. Though an admirer, I'm no jelly expert by any means, but can offer a few facts about them.
Jellies comprise the phylum Cnidaria, within which there are an estimated 9,000 species. They all have jellylike bodies, tentacles and stinging cells. Within the phylum there are three sub-groups: the scyphozoans, examples of which are the Moon Jelly (Aurelia aurita), the various sea nettles, the Crystal Jelly (Aequorea victoria), and the Cannonball (Stomolophus meleagris); the anthozoans, which include corals and anemones; and the hydrozoans, which are mainly colonial organisms (such as Fire Coral and Roselaced Coral) but may also be free-floating (like the notorious Portuguese man-of-war, Physalia physalis).
Indonesian Sea Nettle Crystal Jelly Moon Jelly
Comb Jellies
As beautiful and fascinating as they are, jellies are simple creatures at heart — though they haven't got one. They also have no brain, no lungs, no gills, no blood, no bones, no scales. A medusa is essentially two layers of cells with a jelly-like substance sandwiched between. A neural net provides the senses that guide them through their world. they are sensitive to light, smell, and taste. Fluid filled sacs along their edges allow them to orient themselves. Most medusae have tentacles dangling from the edge of their bells, some have "arms" around their mouths, which are in the center of their undersides and lead directly to their stomachs. Food enters the stomach directly and waste goes out the way it came in.
Flower Hat Jellies
A medusa does have muscles, and it uses these to jet-propel itself through the water. As it does it preys on, catches and consumes its food. Though they are strong swimmers that can travel long distances relative to their size in a day's time, medusae are at the mercy of strong currents. Those that float on the surface — like the Portuguese man-of-war — are blown by the wind and carried by the waves. Any jelly that winds up on the shore is doomed with no way back into the water.
While some jellies are hermaphrodites, medusae reproduce sexually. The females produce eggs which travel from their reproductive organ to their mouth arms. When fertilized by water-borne sperm that have been released by male medusae, the eggs remain on the female's mouth arms until they develop into a flat larval shape. The larvae then are released to float with the currents and eventually attach to hard surfaces where they will develop into polyps. As they grow, the polyps produce tentacles to feed themselves, and may produce branches that break off to become separate individuals. It may take months or even years, but eventually each polyp will be transformed into a stack of disks and these disks will separate from one another into individual jellies.
The lovely thing about watching jellies in an aquarium is that there is no danger of coming in contact with them. Not all jellies sting, but most do. Some stings are hardly noticeable, but others are really horrible — they burn like fire and cause angry welts to rise. I was stung once along the Texas coast and hope never to experience that again — not fun! But I find the grace and beauty of jellies mesmerizing when I don't have to worry about a close encounter of the painful kind. I hope you will find them fascinating, too, in this montage of a few videos I took at the Monterey Bay Aquarium. The music is "Echoes" by Stephan Siebert. Enjoy!
(If you cannot see the video below on your device, click here).
Jellies 2 from Susan Weaver on Vimeo.
Sources:
The Monterey Bay Aquarium
Animal Diversity Web, University of Michigan, Museum of Zoology
The video and photos, except were noted, are mine.
Video music:
"Echoes" by Stephan Siebert is used under a CreativeCommons license, and was accessed at:
http://freemusicarchive.org/music/Stephan_Siebert/11_songs_of_28_years/Stephan_Echos