PLATE 1.  Types of jellyfish, clockwise from upper left: Chrysaora achlyos, a scyphozoan 3 feet in diameter (photo by Gary Florin, Cabrillo Marine Aquarium); Aequorea sp., a hydrozoan 2 inches in diameter (photo by Karen Gowlett-Holmes); Craspedacusta sowerbyi, a freshwater jellyfish 1 inch in diameter; Chironex fleckeri, the deadly Australian box jellyfish 1 foot in diameter; Carukia barnesi, an Irukandji jellyfish-1/2 inch in diameter; Catostylus mosaicus, a rhizostome blubber 1 foot in diameter; Bolinopsis sp., a ctenophore comb jellyfish the size of an egg; Linuche unguiculata, a coronate-1/2 inch in diameter (photo by Ron Larson); Thalia democratica, a salp-1/2 inch long (center; photo by David Wrobel).

PLATE 2.  Problem jellyfish species. Top row: Chrysaora quinquecirrha, Chesapeake Bay, USA, 6 inches in diameter; Carybdea rastonii, Sydney, Australia, 1 inch in diameter (photo by Karen Gowlett-Holmes). Second row: Periphylla periphylla, Norway, 1 foot tall (photo by David Wrobel); Mnemiopsis leidyi, Black Sea, the size of an egg; Phyllorhiza punctata, Gulf of Mexico, 1 foot in diameter (photo by Sue Morrison); Third row: Aurelia labiata, Diablo Canyon Nuclear Power Plant, California, USA, 1 foot in diameter); Crambione mastigophora, Western Australia, 4 inches in diameter (photo by Caroline Williams). Bottom row: Pelagia noctiluca, Mediterranean and United Kingdom, 2 inches in diameter); Nanomia cara, Gulf of Maine, up to 12 feet long (photo by Marsh Youngbluth, Harbor Branch Oceanographic Institute).

PLATE 3.  Jellyfish blooms. A, Thousands of Santa’s hat jellyfish, Periphylla periphylla, caught in a trawl net in Lurefjorden, Norway (photo by Jennifer E. Purcell). B, Bloom of zillions of sea nettles, Chrysaora fuscescens, up to the size of basketballs, in Monterey Bay, California, November 2010 (photo by Arlo Hemphill).

PLATE 4.  Jellyfish clogging problems. A, Thousands of jellyfish polyps (hydroids) growing on a salmon aquaculture cage, Norway (photo by Thor Nielsen/SINTEF). B, Hundreds of jellyfish blocking the grills at the Hadera Nuclear Power Station near Tel Aviv, Israel, 5 July 2011 (photo ©AFP).

PLATE 5.  Nemopilema nomurai, the sumo wrestler–sized jellyfish plaguing the fishing grounds in the Sea of Japan. A, A scuba diver tagging a large medusa (photo ©AFP). B, Hundreds of large Nemopilema in a fishing net (photo ©Asahi Shimbun).

PLATE 6.  Overfishing: evidence of big fish and large numbers. A, Abalone shell mound, Santa Barbara, California, ca. 1920 (Census of Marine Life). B, Atlantic halibut, Provincetown, Massachusetts, ca. 1910 (Census of Marine Life). C, Black marlin, New Zealand, ca. 1933 (photographer unknown, provided by Callum Roberts).

PLATE 7.  Heavy take of two species now in peril. A, Tuna in the Tsukiji Fish Market, Tokyo, 2007 (photo by Amanda Hamilton). B, Netful (60–80 tons) of orange roughy, Great Australian Bight, 1989 (photo by Karen Gowlett-Holmes).

PLATE 8.  Eutrophication. A, Mississippi River sediment-laden, nutrient-rich freshwater plume entering the Gulf of Mexico. The sediments will settle out but the dissolved nutrients will be carried far along the shelf, leading to the formation of hypoxia (photo by Nancy N. Rabalais, Louisiana Universities Marine Consortium). B, This is not a gravel road; the “gravel” is millions of dead fish and the “cracks in the road” are ribbons of oil in a shipping channel in Venice, Louisiana, September 2010 (photo by P. J. Hahn).

PLATE 9.  Trawling damage. A, Trawling mud trails stirring up sediments that choke filter feeding organisms, Gulf of Mexico off the Louisiana coast, 24 October 1999 (photo by NOAA Landsat). B, Typical upper continental slope soft-bottom habitat showing furrows made by recent trawling (left) adjacent to less disturbed habitat from past trawling (right); fragments of benthic fauna (brittlestars) and overturned coarse sediments open up new habitat to be colonized by opportunistic and weedy species such as jellyfish polyps. Southern Australia 28 November 2004, depth of 318 meters (photo ©CSIRO Marine and Atmospheric Research).

PLATE 10.  Pollution. A, Sign warning of unsafe fish at Los Angeles, California (photo by Gary Florin/Cabrillo Marine Aquarium). B, Flesh-footed shearwaters (mutton-birds) with normal plumage (above) and with abnormal white spotting (below), indicating radiation damage (photos by Jennifer Lavers). C, Permanent signage installed to warn of unsafe water flowing into the Tamar Estuary, Launceston, Tasmania, Australia (photo by Robin Smith).

PLATE 11.  Introduced species. A, An urchin barren where kelp and abalone used to be plentiful, Santa Cruz Island, California (photo by Dan Richards). B, An aggregation of Asterias amurensis, the Japanese seastar, that has established itself as a dominant pest in southern Australian waters (photo by Gary Bell/CSIRO).

PLATE 12.  Climate change. A, Polar bears are turning to cannibalism as their habitat and food sources diminish with climate change (photo © Picture Media). B, Permafrost bluffs eroding at near the Inupiuq village of Kaktovik on the Beaufort Sea, Alaska (photo © Hugh Rose/Accent Alaska).

PLATE 13.  Variety of phytoplankton and microzooplankton found in coastal waters, mostly about 50–100 micrometers (about 2/1,000–4/1,000 of an inch) in diameter. Top row: ciliate, Proboscia, Chaetoceros. Middle row: tintinnid, Mastogloia, Hemiaulus, Asteromphalus. Bottom row: Ditylum, Planktoniella. (All photos by Pru Bonham, used with cooperation of CSIRO Marine and Atmospheric Research.)

PLATE 14.  Effects of ocean acidification: Rows 1 and 2, left: the sea butterfly (pteropod) Limacina helicina in healthy condition from above the aragonite saturation horizon (1,000-meter depth) and in a degraded condition from unsaturated waters (2,000-meter depth),1⁄20 of an inch (photos by Dr. Donna Roberts, Antarctic Climate and Ecosystems Cooperative Research Centre). Rows 1 and 2, right: Limacina helicina alive, to 1/3 of an inch (photo by Russ Hopcroft) and its predator the sea angel Clione limacina, 1 inch long (photo by Alexander Semenov/White Sea Biological Station). Row 3: the coccolithophore Emiliania huxleyi in normal (left) and with evidence of malformation from acidified conditions (right). Images taken with a scanning electron microscope, about 1/10,000 of an inch (images by Joana C. Cubillos). Row 4: the calcareous nannofossil Discoaster before (left) and during (right) the Paleocene-Eocene thermal maximum (PETM) ocean acidification event about 56 million years ago. Note the corrosion in the PETM specimen due to acidification. Images taken with a scanning electron microscope, about 1/10,000 of an inch (images by Patrizia Ziveri /VU Amsterdam).

PLATE 15.  Fishing down the food web. Trophy fish taken aboard the charter boat Gulf Stream in the Florida Keys. A, 1950s, aboard Gulf Stream I (photo from Wil-Art Studio/Monroe County Library). B, ca. 1970s, aboard Gulf Stream II (photo from Dale McDonald Collection/Monroe County Library). C, ca. 1990s, aboard Gulf Stream III (photo from Dale McDonald Collection/Monroe County Library).

PLATE 16.  A, Noctiluca scintillans, a red tide dinoflagellate (about 1 millimeter in diameter). B, A red tide of Noctiluca in a bay in southern Tasmania, Australia; the rings are salmon aquaculture pens (photo by Dr. Judi Marshall and Prof. Gustaaf Hallegraeff, University of Tasmania). C, Each of the dots and circles is a fossilized jellyfish, up to 3 feet in diameter, in a mass stranding event 500 million years ago, Late Cambrian, Mosinee, Wisconsin.