The. Main Story by Cabell Davies PHD. Photography by

Dr i f te r s... The Main Story by Cabell Davies PHD Photography by Russ Hopcroft PhD

There are more animals in the sea than on land many times more. The dominant forces behind all life on earth are the tiny, minute beings that drift across the vast expanse of the ocean. he term Plankton, for microscopic, infinitesimal animals, first coined in 1887 by Victor Henson at the University of Kiel, Germany, is derived from the Greek word planktos, meaning drifter. Most offspring of marine animals in larvae form do not resemble their parents such as tarpon, bonefish, and eels. However there are some that are simply miniatures Most offspring of marine animals in larvae form do not resemble their parents such as tarpon, bonefish, and eels. However there are some that are simply miniatures of their parents like the octopus, squids and anemone. of their parents like the octopus, squids and anemone. Plankton has evolved an extremely diverse range of body shapes and sizes in their attempt to adapt to the pelagic marine environment. Often wildly elaborated body forms of plankton are reminiscent of creatures from George Lucas s Star Wars series. George must have been deeply inspired by the ocean. Valdviellia insignis is a deep-sea predatory copepod. It attacks prey with Edward scissor-hands like mouthparts which are visible in this image. Her two large purple eggs are also visible. Size 11mm. (Front page) Atlanta peroni is a heteropod, one of the pelagic snails. It swims by rowing the 2 lobes of its foot, while using its well-developed eyes to search for other pelagic snails on which it feeds. Size 1cm. Euchaeta marina is a common shallow-water predatory copepod in tropical waters. This female carries a clutch of several dozen bright blue eggs. Size 3-4 mm. 24 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 25

While the many familiar marine animals Copepods have evolved to be the fastest have larval stages, these species are not the animals on earth relative to body size. dominant members of the zooplankton. Using a high-speed video microscope, In fact, the vast majority of zooplankton copepods have been clocked at 500 body spend their entire lives as holoplankton lengths per second. By comparison, an and they are unfamiliar to the average folk. F-16 fighter jet flies at best 50 body lengths Important groups of holoplankton, are per second. In that perspective, the cheetah the copepods that are the most numerous cannot be the fastest animal on earth! If a The amphipod Phronema has hollowed out a zooplankter called a salp into which she will lay her eggs. She will then swim this living nursery around until her babies are large enough to leave home. Size up to 3 cm Copepods thrive in the world s ocean and freshwater environments, with an estimated global population of one quintillion (10 18 ). That s a half-billion copepods for every person on earth! animals on earth 1, yet most of us have no clue of their existence. Copepods are small crustaceans ranging in size as adults from about ½ mm up to 10 mm ( see picture of Valdvielia and Euchaeta). Copepods thrive in the world s ocean and freshwater environments, with an estimated global population of one quintillion (10 18 ). That s a half-billion copepods for every person on earth! Copepods are a primary sustenance for many larger plankton, adult fish, and whales. As they are near the bottom of the food chain, evading predators is a necessity. copepod is transformed in ratio to the size of a cheetah, in comparison, the cheetah would run at 70 miles per hour (112 km/h) at its top speed, and the copepod would zoom past at 2,000 miles per hour (3219 km/h) through water which is 800 times denser than air. This mesmerizing feat is achieved by the copepods when they transform their bodies from a typical T feeding posture, with their antennules spread wide (as illustrated in picture of Valdvielia and Euchaeta), into a torpedo shape with the antennules laying alongside the body while the swimming legs propel the animal forward with blinding speed. 1 with the possible exception of roundworms The amphipod Mimonectes sphaericus (formerly necto amphipod) is a commensal on deep-sea jellyfish and their kin. The large knife-like antennae indicate this is a male. Size 3 mm. Basin circulation: It reflects the connection between the surface and deep water flow, in the global Ocean-conveyer belt that takes between 600 and 1600 years to complete. 26 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 27

Pelagobia longicirrata is a pelagic Polychaete worm, from the deep Arctic Ocean; the orange color comes from oil drops stored in the body. Size 5 mm. This green polychaete worm has left the seafloor to lay her clutch of pink eggs in the plankton. Size 4-5 mm. Alacia valdiviae is a deepwater Ostracod or clamshrimp, a small crustacean protected by two clam-like shells. They are important scavengers in the deep-sea. Size 4-5 mm. 28 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 29

The sea-angel Clione limacina is a predatory pteropod, another shell-less pelagic snail that flies through the water with it s tow wings, hunting for other snails to eat. Size up to 3 cm. There are many other groups of holoplankton with equally fascinating life histories and behaviors. An example includes the amphipods (Phronema and Necto amphipod), which are voracious predators of copepods. The amphipod Phronema with large compound eyes and scythe-like appendages is actually a crustacean that breeds it young inside a salp, Carinaria lemarcki is another species of heteropod (pelagic snail), but unlike Atlanta it is no longer able to fit inside its shell. The end of the snout is equipped with strong hook-like teeth used or extracts other snails from their shells. Size 3-4 cm. The amphipod Phronema with large compound eyes and scythe-like appendages is actually a crustacean that breeds it young inside a salp, a jelly like animal. a jelly like animal. It t has to kill the salp first, and then move in and use its jellish body as nest to breed. Another interesting crustacean group is the Ostracods (Alacia valdiviae) which are active swimmers and have a clam-like shell for protection. Many of the deep-dwelling zooplankton, like that of Ostracods are red, which make them nearly invisible at depth as the red is readily absorbed by seawater. By contrast, species that live near the surface in tropical regions are often blue, matching the colour of the ocean s surface. Marine worms called Polychaetes, (Green Ploy, Pelagobia longicirrata), equipped with rows of swimming appendages for rapid movement are also the copepods predators. 30 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 31

The shelled pteropod Diacria trispinosa feeds by secreting a bubble of mucus from its large fleshy wings. As it sinks from the weight of the shell, food gets stuck to the bubble, then both the bubble and the attached food are eaten. It then uses the wings to swim back to shallower water and start the process over again. Size up to 2 cm. The Pteropods are marine snails that have adapted to life in the ocean by using a foot to swim swiftly through the water column. Some pteropods have little or no shell and they are slug-like predators (Carinaria and Clione) of the shelled Pteropods (Limacina, Janthina, Diacria, and Atlanta). The pelagic nudibranch, Phylliroe atlantica, has a larval stage that burrows into a jellyfish, eats it from the inside out, and becomes a free-living adult. Larger plankton includes various kinds of shrimp, which feed on Phytoplankton (plants plankton) as well as on smaller zoo- plankton such as the Eusirus. Jellyfish, which can grow up be up to a meter in The pelagic nudibranch, Phylliroe atlantica, has a larval stage that burrows into a jellyfish, eats it from the inside out, and becomes a freeliving adult. diameter are considered planktonic since they drift with ocean currents, and there is a wide variety of these important predatory species. Siphonophores (see picture of Abyla duck siph and Hippodius) are colonial animals, related to jellyfish that include the deadly Portuguese Man of War (Physalia utriculus) commonly known as the blue bottles in Australia. Janthina umbilicata is a snail that lives in a unique habit within the ocean called the neuston. It secretes a mat of sticky bubbles that keep it attached to the ocean s surface, where it hunts for jellyfish that live in the same special habitat. Size 6-7 mm. Limacina helicina is a shelled pelagic snail common in temperate through polar waters. They are sometimes observed to gather together into swarms. Size up to 1 cm. 32 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 33

The pelagic snail Phylliroe atlantica begins life as a parasite within jellyfish, but as it grows, it becomes a predator on them. It swims using its flattened tail. Size up to 4 cm. The diversity of zooplankton is enormous, comprising of species from all animal phylum. Zooplankton includes most of the nearly half-million non-insect animal species on earth. In addition to its diversity, the shear mass of zooplankton in the ocean is of colossal proportions; if all the zooplanktons were sieved from the sea and spread across the USA, Australia and China, the resulting layer would be meters deep and the vast majority will be copepods. These ocean drifters impact not only upon the yield of global fisheries but more importantly the global carbon and nitrogen cycles. This huge mass of zooplankton turns over several times per year through birth, growth and death. Zooplankton, together with the even larger masses of bacterioplankton, protozoa, and phytoplankton, are at the base of the ocean s food web. These ocean drifters impact not only upon the yield of global fisheries but more importantly the global carbon and nitrogen cycles. Hippopodius hippopus is a colonial Siphonophore, closely related to jellyfish. The swimming bells along the side of the colony move it around, while the orange and yellow tentacles are normally stretched out trying to capture other zooplankton as prey. Size up to 2 cm. Abyla sp. is a deep-sea Siphonophore, closely related to jellyfish. This is a colony of two individuals, that swim by pumping water, and capture food like a long-line fisherman. Size 30mm. As the majority of marine species do not provide parental care for their young, the ocean becomes an organic soup nourishing the eggs and larvae of sea animals. However the sea does not always provide sufficient food, and the young animals suffer great losses to a variety of predators. To compensate, marine species generally lay large masses of eggs. The numbers reaching adulthood can vary by a factor of hundreds from one generation to the next, greatly affecting the adult population size. The factor affecting survivorship from egg to adult, or recruitment in scientific terms, remains poorly understood and is the subject of intensive study. 34 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 35

Planktons are passive drifters where their distribution is affected by oceanic circulation. Biological and physical oceanographers are working together to unravel the underlying mechanisms controlling zooplankton diversity and distributions. A combination of traditional sampling methods, using plankton nets This baby octopus spends its early life hunting in the plankton, soon it will move to the seafloor beginning the cryptic life-style of the adult. Some of the color-changing cells are already visible. Size 1 cm. The multi-net is a modern collecting tool for zooplankton. It allows us to electronically open and close nets at different depths within the ocean to determine where different species live and how many of them are found at each depth. It operates down to 6000m depth. The vast array of animal life in the ocean is truly remarkable to behold, and it is incumbent upon us to understand and preserve this vital component of our planet. and new high tech DNA methods and digital imaging tools such as a VPR (video plankton recorder) are shedding new light on zooplankton diversity and how they are affected by natural environmental factors and human impact. These new tools allow for automated measurement and development of ocean observing systems, which, together with computer models of plankton biology and ocean circulation, pave the way for a new era in understanding and predicting how marine life is impacted by pollution, over-harvesting, and climate change. The vast array of animal life in the ocean is truly remarkable to behold, and it is incumbent upon us to understand and preserve this vital component of our planet. The arctic amphipod Eusirus holmii uses its praying-mantis like clams to capture prey. They have been observed attached to sea ice, on the deep-sea floor and swimming in between the 2 habitats. Size up to 3 cm. This baby sea-anemone has spent its early life feeding on zooplankton. Soon it will settle to the seafloor to begin the remainder of its life. Size 2-3 mm. 36 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 37

Ca r ptu i ng Drifters... Russ Hopcroft PhD ith a bit of thought, one then thinks of the animals that crawl or are anchored to the seafloor, such as corals and the massive reef structure that they build. A far more important part of ocean exists hidden from your perspective, the realm of the zooplankton small drifting animals found throughout the world s oceans. Zooplankton are the primary conduits between the tiny floating algae that capture the sun s energy and the larger animals such as fish, seabirds and marine mammals. Everyone knows at least one type of zooplankton, the jellyfish. Although j e l l y f i s h a r e sometimes meters in length, like all zooplankton they Everyone knows at least one type of zooplankton, the jellyfish. Although jellyfish are sometimes meters in length, like all zooplankton they have little control over where they are carried by the ocean s currents. have little control over where they are carried by the ocean s currents. Most zooplankton are smaller, and many are just specks to the naked eye. This small size is unfortunate, because within the zooplankton there is an incredible range of life. (Left) The pelagic polychaete worm Tomopterus (formerly Pl1) is a predator on other soft-bodied zooplankton. It swims using the flattened paddles along the side of its body called parapodia. Size usually up to 4-5 cm, but some species can exceed 1 m. (Top) Branchiostoma (old name was Amphioxus) larvae are filter-feeders with many of the characteristics of the most primitive vertebrates (hagfish and lampreys). Size 2 cm. The ways they go about their lives, hunt for, capture, and ingest their food are frequently unimaginable. I often believe the inspiration for many of the creatures in science fiction movies come from animals that live within the plankton. F o r t h e m o s t part, zooplankton a re t r a n s l u c e n t creatures. Many are vividly pigmented, appearing as bizarre as they are beautiful. There are currently about 7000 recognized species of full-time zooplankton, and an even greater number that live in the plankton only for the early part of their lives before moving to the seafloor. Nonetheless, the range of body design is extreme: some have hard shells, while others are literally bags of water. Some are peaceful grazers while others are viscous predators. The ways they go about their lives, hunt for, capture, and ingest their food are frequently unimaginable. I often believe the inspiration for many of the creatures in science fiction movies come from animals that live within the plankton. Sadly, these animals are easy damaged by the process of collection, and both their unique transparency and rich colors cannot be maintained for long. The only way to appreciate the wonder of these animals is to see them alive, either directly in the water diving, through electronic eyes on underwater robots, or immediately after they are collected with specialized nets. For several years, I have been working to share my fascination of zooplankton with people by capturing them as digital images. Through projects within the Census of Marine Life, I ve been fortunate to participate 38 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 39

About the authors Cabell Davis PHD Ocean Geographic Oceanographer in Residence Dr Davis is a Senior Scientist at Woods Hole Oceanographic Institution and is the Director of WHOI s Ocean Life Institute with over 30 years experience in plankton ecology. He has conducted research on 50 oceanographic cruises and co-developed the Video Plankton Recorder, an underwater video microscope with automatic imaging of high-resolution fragile plankton data. He recently worked with MIT engineers to develop a small underwater digital holographic camera for imaging plankton. He is now modeling the impact of climate change on the fisheries ecosystem. His current interests are in developing, modeling and observing systems in support of ecosystem approaches to managing ocean resources. The leptocephalus larvae of moray eels are ribbon-like and completely transparent, with only tiny heads. Size up to 15 cm. on research cruises scattered around the globe, from the tropics to both poles. I ve collected from the ocean s surface waters to depths of several kilometers. What started out as an activity during my spare time on cruises can become a full-time activity, either hunting for larger zooplankton with ROVs (remotely operated vehicles) or sifting through net samples to find healthy undamaged subjects. Expert coworkers help me identify animals when they are unfamiliar. I then spend hours trying to capture the perfect picture, of a moving animal, on a moving ship. It s a challenge, but I hope you agree, it s worth the effort. *all photography by Russ Hopcroft Russ Hopcroft PHD Associate Professor Institute of Marine Science, University of Alaska, Fairbanks Dr. Russ Hopcroft is an Associate Professor at the University of Alaska s Institute of Marine Science in Fairbanks. He grew up fascinated by aquatic life (and Jacques Cousteau specials), pursuing the sciences during his education. Dr. Hopcroft received his Masters degree in 1988, and his Ph.D. in 1997 from the University of Guelph, Ontario, Canada. The focus of his graduate research was on marine plankton ecology in the tropical waters surrounding Jamaica, West Indies. From 1997 to 1999, he was a Post-doctoral Fellow at the Monterey Bay Aquarium Research Institute (MBARI). At MBARI he was heavily involved in the use of ROVs, as well as traditional oceanographic surveys, to study the oceans. Dr. Hopcroft pursues a broad array of research interests, concentrating on the composition, production and energy flow of the planktonic trophic levels that ultimately shape the structure of all marine communities. Since joining UAF in 2000, most of his research focuses on copepod and euphausiid crustaceans in Alaskan waters. He also specializes on the taxonomy, biology and ecology of the tadpole-like pelagic tunicates, and most recently the pelagic snails. He serves on the steering committee of several Census of Marine Life projects: the Arctic Ocean Biodiversity (ArcOD) project, the Census of Antarctic marine Life (CAML), and the global Census of Marine Zooplankton (CMarZ). He is increasingly recognized for his images of live zooplankton that are widely distributed in the media and on the web. He is an active contributor to ongoing global efforts to molecular barcode all zooplankton species. Visit his web site, http://www.sfos.uaf.edu/directory/faculty/hopcroft/ and http://www. sfos.uaf.edu/research/arcdiv/index.html 40 The Drifters...