DTherifters...

Main Story by Cabell Davies PHD

Photography by Russ Hopcroft PhD There are more 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 .

Euchaeta marina is a common shallow-water predatory copepod in he term “Plankton”, for Valdviellia insignis is a deep-sea tropical waters. This female carries a microscopic, infinitesimal predatory copepod. It attacks prey with clutch of several dozen bright blue eggs. animals, first coined in 1887 by Victor Henson at the “Edward scissor-hands” like mouthparts Size 3-4 mm. University of Kiel, Germany, which are visible in this image. Her is derived from the Greek two large purple eggs are also visible. word “planktos,” meaning “drifter”. Most offspring of Size 11mm. 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 (Front page) Atlanta peroni is a extremely diverse range of body shapes and sizes in their attempt to adapt to heteropod, one of the pelagic snails. It the pelagic marine environment. Often swims by rowing the 2 lobes of its foot, wildly elaborated body forms of plankton while using its well-developed eyes to are reminiscent of creatures from George Lucas‘s Star Wars series. George must have search for other pelagic snails on which been deeply inspired by the ocean. it feeds. Size 1cm.

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 on earth! If a animals on earth1, yet most of us have no copepod is transformed in ratio to the size The amphipod Phronema has clue of their existence. Copepods are small of a cheetah, in comparison, the cheetah Copepods thrive in crustaceans ranging in size as adults from would run at 70 miles per hour (112 hollowed out a zooplankter called a salp the world’s ocean about ½ mm up to 10 mm ( see picture km/h) at its top speed, and the copepod into which she will lay her eggs. She will and freshwater of Valdvielia and Euchaeta). Copepods would zoom past at 2,000 miles per hour then swim this living nursery around thrive in the world’s ocean and freshwater (3219 km/h) through water which is 800 environments, with environments, with an estimated global times denser than air. This mesmerizing until her babies are large enough to leave an estimated global population of one quintillion (1018). That’s feat is achieved by the copepods when home. Size up to 3 cm population of one a half-billion copepods for every person they transform their bodies from a typical 18 on earth! “T” feeding posture, with their antennules quintillion (10 ). spread wide (as illustrated in picture of That’s a half-billion Copepods are a primary sustenance for Valdvielia and Euchaeta), into a torpedo many larger plankton, adult fish, and shape with the antennules laying alongside copepods for every whales. As they are near the bottom of the the body while the swimming legs propel person on earth! food chain, evading predators is a necessity. 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 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 deep- water Ostracod or clam- shrimp, 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 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 The amphipod Phronema with large species of heteropod (pelagic compound eyes and scythe-like snail), but unlike Atlanta it is no appendages is actually a crustacean longer able to fit inside its shell. that breeds it young inside a salp, The end of the snout is equipped a jelly like animal. with strong hook-like teeth used or extracts other snails from a jelly like animal. It t has to kill the salp their shells. Size 3-4 cm. 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 , 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 Janthina umbilicata is a snail that atlantica, has a larval stage that lives in a unique habit within the ocean burrows into a jellyfish, eats it from called the neuston. It secretes a mat of the inside out, and becomes a free- sticky bubbles that keep it attached to living adult. the ocean’s surface, where it hunts for jellyfish that live in the same special diameter are considered planktonic since habitat. Size 6-7 mm. Limacina helicina is a shelled pelagic snail they drift with ocean currents, and there is a wide variety of these important predatory common in temperate through polar waters. species. Siphonophores (see picture of They are sometimes observed to gather Abyla duck siph and Hippodius) are colonial together into swarms. Size up to 1 cm. animals, related to jellyfish that include the deadly Portuguese Man of War (Physalia utriculus) commonly known as the blue bottles in Australia.

32 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 33 The diversity of zooplankton is enormous, comprising of species from all animal phylum. Zooplankton includes most of the nearly half-million non-insect animal The pelagic snail Phylliroe species on earth. In addition to its diversity, atlantica begins life as a parasite the shear mass of zooplankton in the within jellyfish, but as it grows, it ocean is of colossal proportions; if all the zooplanktons were sieved from the sea becomes a predator on them. It and spread across the USA, Australia and swims using its flattened tail. Size up China, the resulting layer would be meters to 4 cm. 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.

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 Abyla sp. is a deep-sea Siphonophore, food, and the young animals suffer closely related to jellyfish. This is a great losses to a variety of predators. To Hippopodius hippopus is a colonial compensate, marine species generally lay colony of two individuals, that swim by Siphonophore, closely related to large masses of eggs. The numbers reaching pumping water, and capture food like jellyfish. The swimming bells along adulthood can vary by a factor of hundreds a long-line fisherman. Size 30mm. from one generation to the next, greatly the side of the colony move it around, affecting the adult population size. The while the orange and yellow tentacles factor affecting survivorship from egg to are normally stretched out trying to adult, or “recruitment” in scientific terms, remains poorly understood and is the capture other zooplankton as prey. subject of intensive study. Size up to 2 cm.

34 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 35 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 Planktons are passive drifters where of the color-changing cells are already their distribution is affected by oceanic visible. Size 1 cm. 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 The vast array of The arctic amphipod Eusirus holmii animal life in the ocean uses its praying-mantis like clams to capture is truly remarkable prey. They have been observed attached to sea to behold, and it is ice, on the deep-sea floor and swimming in incumbent upon us between the 2 habitats. Size up to 3 cm. to understand and preserve this vital The multi-net is a modern collecting tool for component of zooplankton. It allows us to electronically open and close our planet. nets at different depths within the ocean to determine where different species live and how many of them are and new high tech DNA methods and digital imaging tools such as a VPR (video found at each depth. It operates down to 6000m depth. 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, This baby sea-anemone pave the way for a new era in understanding has spent its early life feeding on and predicting how marine life is impacted by pollution, over-harvesting, and climate zooplankton. Soon it will settle to change. The vast array of animal life in the the seafloor to begin the remainder ocean is truly remarkable to behold, and of its life. Size 2-3 mm. it is incumbent upon us to understand and preserve this vital component of our planet.

36 The Drifters... OCEAN GEOGRAPHIC 5:3/2008 37 Capturing Drifters... The ways they go about their lives, hunt for, capture, and ingest their Russ Hopcroft PhD food are frequently unimaginable.

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

Russ Hopcroft PHD Associate Professor The leptocephalus Institute of Marine Science, University of larvae of moray eels are Alaska, Fairbanks Dr. Russ Hopcroft is an Associate Professor ribbon-like and completely at the University of Alaska’s Institute of Marine transparent, with only tiny Science in Fairbanks. He grew up fascinated by aquatic life (and Jacques Cousteau specials), pursuing the sciences during his heads. Size up to 15 cm. 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 on research cruises scattered around the Jamaica, West Indies. From 1997 to 1999, he was a Post-doctoral Fellow at globe, from the tropics to both poles. I’ve the Monterey Bay Aquarium Research Institute (MBARI). At MBARI he was collected from the ocean’s surface waters to heavily involved in the use of ROVs, as well as traditional oceanographic depths of several kilometers. What started surveys, to study the oceans. out as an activity during my ‘spare time’ Dr. Hopcroft pursues a broad array of research interests, concentrating on the on cruises can become a full-time activity, composition, production and energy flow of the planktonic trophic levels that either hunting for larger zooplankton ultimately shape the structure of all marine communities. Since joining UAF in with ROVs (remotely operated vehicles) 2000, most of his research focuses on copepod and euphausiid crustaceans or sifting through net samples to find in Alaskan waters. He also specializes on the , biology and ecology healthy undamaged subjects. Expert co- of the tadpole-like pelagic tunicates, and most recently the pelagic snails. He workers help me identify animals when serves on the steering committee of several Census of Marine Life projects: they are unfamiliar. I then spend hours the Arctic Ocean Biodiversity (ArcOD) project, the Census of Antarctic marine trying to capture the perfect picture, of a Life (CAML), and the global Census of Marine Zooplankton (CMarZ). He is moving animal, on a moving ship. It’s a increasingly recognized for his images of live zooplankton that are widely challenge, but I hope you agree, it’s worth distributed in the media and on the web. He is an active contributor to ongoing the effort. global efforts to molecular barcode all zooplankton species. Visit his web site, http://www.sfos.uaf.edu/directory/faculty/hopcroft/ and http://www. *all photography by Russ Hopcroft sfos.uaf.edu/research/arcdiv/index.html

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