In the Ocean (Under the Microscope)

Under the Microscope

In the

Ocean Sabrina Crewe Consultant: Professor Anne K. Camper, Montana State University

Copyright © 2010 by Infobase Publishing All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For information contact: Chelsea Clubhouse An imprint of Chelsea House 132 West 31st Street New York NY 10001 Library of Congress Cataloging-in-Publication Data Crewe, Sabrina. In the ocean / Sabrina Crewe ; consultant, Anne K. Camper. p. cm. -- (Under the microscope) Includes index. ISBN 978-1-60413-827-6 (hardcover) ISBN 978-1-4381-3468-0 (e-book) 1. Marine organisms--Juvenile literature. I. Title. II. Series. QH91.16.C74 2010 578.77--dc22 2010000180 Chelsea Clubhouse books are available at special discounts when purchased in bulk quantities for businesses, associations, institutions, or sales promotions. Please call our Special Sales Department in New York at (212) 967-8800 or (800) 322-8755. You can find Chelsea Clubhouse on the World Wide Web at http://www.chelseahouse.com Text design by Sabine Beaupré Illustrations by Stefan Chabluk Originated by Discovery Books Composition by Discovery Books Cover printed by Bang Printing, Brainerd, MN Book printed and bound by Bang Printing, Brainerd, MN Date printed: May 2010 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 This book is printed on acid-free paper. All links and Web addresses were checked and verified to be correct at the time of publication. Because of the dynamic nature of the Web, some addresses and links may have changed since publication and may no longer be valid. Acknowledgments We would like to thank the following for permission to reproduce photographs: H.M.S. Challenger Library: p. 29; Dennis Kunkel Microscopy, Inc.: pp. 8, 24, 25 both; MicroAngela: pp. 4, 16, 20, 22 left, 23; NOAA: pp. 10 both, 11, 14, 19, 22 right, 26 (1), (3), (4), and (5), 27 top left, top right, middle right, and bottom; Science Photo Library: pp. 9 (Steve Gschmeissner), 12 (Sinclair Stammers), 13 (Claire Ting), 17 both (Steve Gschmeissner), 18 (Volker Steger and Christian Bardele), 21 (Dante Fenolio), 26 (2) (Science Source); Shutterstock Images: pp. 5 (Emin Kuliyev), 6 (Pinosub), 15 (Armin Rose), 27 middle left (Vittorio Bruno).

Contents Invisible Oceans

4

The Ocean Web

6

Ocean Bacteria

8

Life in the Deep

10

Cyanobacteria

12

All About Algae

14

Amazing Phytoplankton

16

Zooplankton

18

Crustaceans

20

Micromollusks

22

Protozoa

24

Larvae

26

Size and Scale

28

About Microscopes

28

Micro-Detective

29

Glossary

30

Explore These Web Sites

31

Index

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Some words are bold the first time they appear in the text. These words are explained in the glossary at the back of this book.

Invisible Oceans The oceans that cover most of Earth are vast, with towering waves and dark depths. Huge whales, enormous octopuses, and plants as tall as buildings live in this watery world. But there is another, invisible world in the oceans.

Micro-Monster The Lucifer is a very small kind of shrimp that is among the plankton floating in the ocean. The word lucifer means lightbearing or bright, and the Lucifer shrimp can glow in the dark! The Lucifer has eyes sticking out on stalks, which give it a better view of its surroundings.

Microorganisms Living things, such as plants and animals, are known as organisms. Organisms that are too small to see with the human eye are called microorganisms. Many microorganisms that live in the ocean are known as plankton. The word plankton means drifting, and that’s what plankton do. They float and drift with the movement of the water. 

Some plankton are marine animals or animal-like creatures. Others are more like plants. They may be tiny, but these organisms are important for all living things. We’ll find out why, and discover many other things, as we take a look at the ocean under the microscope.

Micro-Scientist

Micro-Fact

A microbiologist is a scientist who studies microorganisms. A marine microbiologist focuses on microscopic life-forms in the ocean.

Near the surface of the ocean, every drop of ocean water contains thousands of plankton. 5

The Sun’s energy passes through the ocean web to all living things.

The Ocean Web To understand the microscopic world of the ocean, we have to learn a little about how all living things in the ocean work together. They depend on each other for food and survival. Microorganisms are an important part of this network.

Phytoplankton and zooplankton As we learned, plankton are the tiny floating organisms in the ocean. Those that are similar to plants are called phytoplankton. Animals or animal-like plankton are known as zooplankton. 6

So what’s the difference? All livings things need energy, and that energy comes from food. Zooplankton eat other living things to get their food. Phytoplankton make their own food through photosynthesis. Using the Sun’s energy, they combine water and carbon dioxide (a mix of carbon and oxygen) to produce carbohydrates.

Micro-Fact Phyto- means plant, and zoo- refers to animals. So phytoplankton means drifting plant, and zooplankton means drifting animal.

Webs and chains

Sun

The Sun’s energy is the starting point for almost all food. Phytoplankton use it to make their own food and grow. Zooplankton eat phytoplankton. Small fish and crustaceans survive by eating zooplankton. Bigger fish and other large marine animals prey on these smaller ones. This passing of energy from one organism to This diagram another is known as a of a marine food food chain. There are chain shows how energy produced by many different food phytoplankton feeds chains, however, and zooplankton they often cross over. and bigger animals. Together, many food chains form a food web. 7

phytoplankton

zooplankton

small crustacean

fish

Ocean Bacteria Living things need nutrients to keep them healthy and help them grow. The nutrients in the ocean come from organisms that die and settle on the ocean floor. There, they are broken down by decomposers. Many decomposers are microorganisms, especially bacteria. Let’s find out more about bacteria and how they play an important part in the ocean web.

What are bacteria? Bacteria are some of the smallest living things in the ocean and on land. They have only one cell, and this cell does not have a nucleus. Bacteria multiply by dividing themselves.

An important job

Many bacteria are rod-shaped, like these ones found in the ocean. They are magnified here more than 5,000 times.

Many kinds of bacteria live among the dead plant and animal matter in the ocean. Most feed by absorbing nutrients from the dead organisms that they live on. Bacteria break down, or decompose, the matter they use for food. This process releases substances into the water that become nutrients for phytoplankton. The most phytoplankton are found in areas where the ocean is rich in nutrients. These nutrients can also come from rivers that flow into the ocean. 8

Viruses One type of microbe is smaller than a bacterium, and that is a virus. Some are so tiny that they are measured in nanometers. Viruses, however, are not really organisms. A virus is a package of chemicals that can only multiply inside a living cell, or host. Viruses invade the cells of plants, animals, and bacteria. In the ocean, viruses infect bacteria living on the ocean floor and plankton in the water.

How Small Is Small? Scientists say that a teaspoonful of seawater contains between 10 million and 100 million marine viruses. They are so small that you would have to put more than 20 billion of them together before you could see them!

A diatom is a type of phytoplankton. If you look closely at these diatoms, you can see the bacteria (white specks) that live on them.

9

Life in the Deep In some parts, the ocean is more than 30,000 feet deep. Not many organisms can live at those depths. There is little or no sunlight. So without the Sun’s energy, how can there be life?

Hydrothermal vents This photo shows a hydrothermal vent deep in the ocean. The cloud comes from the hot water gushing out. The water is full of minerals that provide nourishment for the microorganisms living around the vent.

In the deepest parts of the ocean, there are openings, called vents, in the ocean floor. Boiling water constantly spews out of these hydrothermal vents from deep underground. Thousands of species of microbes live around these openings. They

These tubeworms at a hydrothermal vent get nutrients from bacteria that live in their tubes.

10

Micro-Fact Scientists believe that the microbes in hydrothermal vents are related to the earliest forms of life on Earth.

Extremophiles Any organism that likes to live at extremes is called an extremophile. They survive and flourish where other organisms would die. Most extremophiles are microbes, but some are bigger creatures, like the ones that live around hydrothermal vents. The tiny shrimp above lives in the icy water of the Arctic Ocean. Extremophiles that live in very cold places are known as psychrophiles or cryophiles. Organisms that like hot places are thermophiles. Creatures that tolerate very salty water are halophiles. So as you can imagine, the ocean depths are full of extremophiles!

get their energy from the minerals in the boiling water gushing from the vents. They live on the surface of the vents or on larger creatures that also flourish in this extreme environment.

Archaea Many of the microbes that live in the thermal vents are archaea. These are not animals, plants, viruses, or bacteria. But, like bacteria, they have one simple cell, and they are very tiny. Most archaea are only 1 to 15 micrometers in size. 11

Cyanobacteria As we learned, most bacteria absorb their food from other living things. But there is an important type of bacteria in the ocean that is different.

Using photosynthesis Like other bacteria, cyanobacteria do not have a nucleus in their single cell. But unlike other bacteria, cyanobacteria make their own food. They float on the surface of water and use sunlight to perform photosynthesis. Organisms that use energy from photosynthesis are called phototrophs. And because they are phototrophs, or plant-like, cyanobacteria are part of the floating world we know as phytoplankton.

Trichomes and coccoids Cyanobacteria live together in large Oscillatoria groups. Some form filaments, or is a trichome strands, in which long chains cyanobacteria because of them are joined together. its cells form long strands. You can see the individual These cyanobacteria are called cells that make up trichomes. Others, known as the strands in coccoids, live together in a this photo. group inside a blob of jelly. 12

Bubbles of oxygen Whether they are in chains or blobs, cyanobacteria often form mats over areas of the ocean. As they photosynthesize, cyanobacteria absorb carbon dioxide and release oxygen. You can often see bubbles of oxygen rising from the mats.

Prochlorococcus The smallest known phototroph—only about 0.6 micrometers in size—is a cyanobacterium called Prochlorococcus. But it may also be the most important. There can be 100 million of these cyanobacteria in a quart of seawater. Scientists believe they could perform as much photosynthesis as all other phytoplankton put together.

13

Marine algae produce the same green substance—chlorophyll— that plants do. So, many species are green in color. But some algae can be red, purple, brown, or yellow because they contain other pigments (colors) besides chlorophyll. These red and green algae are growing on rocks in the Pacific Ocean.

Micro-Fact Most algae are microscopic, but some are very big. Large algae are what we know as seaweed, and they can be over 100 feet long.

All About Algae Most kinds of phytoplankton in the oceans belong to a large group of organisms called algae. Algae are plant-like because they perform photosynthesis, but they are not actually plants.

1

What are algae? Algae don’t have stems, roots, or leaves. Algae often live joined together in long strands, but some species float around by themselves. Many algae have just one cell, and they reproduce simply by dividing their cells. Other algae create new cells, called spores, which they release into the water to make new algae.

When ocean water freezes into ice, algae of different colors can make icebergs stripy!

Algae and Earth’s Cycles Algae and cyanobacteria are essential to Earth’s natural cycles. The carbon cycle is the movement of carbon among air, water, and living things. If there is too much carbon in the air, Earth gets too warm. But oceans remove a lot of carbon dioxide from the air by dissolving it in their waters. Phytoplankton help because they take in carbon dioxide from the water during photosynthesis. This allows the oceans to absorb more carbon dioxide from the air. And because they only need the carbon, phytoplankton release the oxygen. They provide the world with about half the oxygen that living things need to survive.

15

Amazing Phytoplankton We learned that all phytoplankton are phototrophs, or plant-like. But some phytoplankton don’t look anything like the plants we know. Let’s see what they do look like under the microscope.

Diatoms

Under the microscope, diatoms reveal their complex patterns.

The most plentiful of all phytoplankton are diatoms. Diatoms are enclosed in a cell wall that forms a hard casing. These cases are made of silica, which is the same stuff that glass is made of. Diatoms come in all kinds of interesting shapes and often have beautiful patterns. Whatever their shape, diatoms are symmetrical, which means that one half is the mirror image of the other.

Coccolithophores Coccolithophores surround themselves with tiny shields only 3 micrometers across. The shields are made of calcite, a hard material that also makes limestone rocks.

16

Unlike other phytoplankton, coccolithophores can survive in water that contains few nutrients.

You can see the microscopic shields that form a ball around this coccolithophore.

Dinoflagellates There are about 2,000 kinds of dinoflagellates, and some of them are phototrophs. They have little tails called flagellae, which help them move. Dinoflagellates can reproduce very fast, Dinoflagellates creating a huge number of cells called come in many a bloom. Some dinoflagellate blooms shapes and range can poison other marine life. These in size from 5 dinoflagellates are red in color, so micrometers to 2 millimeters. their blooms are called “red tides.”

Micro-Fact Some dinoflagellates glow in the dark. You can see a flicker of blue light in the ocean at night if a group of these dinoflagellates is disturbed. 17

Zooplankton Do you remember zooplankton? They are the microscopic animals and animal-like creatures that float in the ocean. There are thousands of species of tiny organisms that make up the zooplankton population. They fall into three main groups: microanimals, protozoa, and the larvae of larger animals.

Protozoa Protozoa are microorganisms that are similar to animals, but they are simpler in structure. Protozoa often have only one cell, and many reproduce by dividing themselves. But they can move around in the water and catch prey to eat. Sometimes, they catch and eat other protozoa bigger than themselves!

Larvae Some larger marine creatures are microscopic when they are larvae. A larva is an animal in the stage before it becomes an adult. Marine 18

This amoeba is a kind of protozoa. It lives in the seas off western Australia and eats diatoms.

larvae may turn into worms, coral, snails, or fish, but they start out as zooplankton. We’ll take a look at some of these later.

These zooplankton are microscopic crustaceans. The one in the center is the larva of a bigger crustacean.

Microanimals Animals are living things that have many cells, can move themselves around, and feed on plants or other animals. With a microscope, you will find a world of miniature animals on land and in the ocean. We call them microanimals because they are too small to be seen easily by the human eye. Microanimals in the ocean feed on other zooplankton and on phytoplankton. Some of the most common microanimals are crustaceans, which we’re going to look at next. 19

Crustaceans Micro-Monster The Pleuromamma is a copepod with antennae as long as its body. The antennae are covered in small hairs that pick up signals, such as smells or movements. This detection system enables the Pleuromamma to attack prey with lightning speed.

Not all crustaceans are microscopic. The crustaceans we picture when thinking about the ocean are bigger animals, such as lobsters and crabs. Shrimp are crustaceans, too. What these crustaceans have in common is a hard outside skeleton. They also have bodies with separate segments, or jointed parts. Many microscopic crustaceans live below the ocean surface and come up at night to feed on plankton. Some live attached to other animals. Others live in the sand on the ocean floor. Yet others create their own houses and float around.

Copepods Copepods are usually 1 or 2 millimeters in length. Some species live on the ocean floor. Others float on or near the surface as zooplankton—

20

in fact there are usually more copepods than any other zooplankton.

Amphipods Amphipods, like copepods, may live at the top or bottom of the ocean depending on their species. Most of them have flat bodies, and they all have three pairs of tail legs that they flick to move quickly through the water.

Micro-Fact Some copepods are parasites, which means they live and feed on a host instead of swimming around to find food. Parasitic copepods live on fish. A large shark may have hundreds on its fins and gills and even in its nose!

A Phronima is an amphipod that lives in the middle and upper areas of the ocean. It makes its home inside another tiny animal called a salp. The Phronima will kill the salp, hollow out its body, and move in!

21

Micromollusks Mollusks in the ocean include everything from the giant squid and octopus to the cowrie and abalone, whose beautiful shells you might find on a beach. On land, mollusks include the snails in your backyard. When scientists talk about micromollusks, however, they usually mean shelled mollusks that live in the ocean. They are so tiny that some of them can’t be seen without a microscope.

This pteropod is a micromollusk with a coiled shell. It lives among plankton in the ocean. The pteropod’s “foot” is formed into flaps that it uses for swimming.

This shell is only 1.5 millimeters long. It was once home to a micromollusk. 22

Sand from the ocean is made up of tiny fragments of shell and rock. This magnified sand from a beach in Hawaii contains micromollusk shells along with fragments of larger shells.

Gastropods The mollusks that live in seashells are called gastropods. Inside their beautiful shells, gastropods have soft bodies. They make their shells with minerals in the water that they process in their bodies and release as a liquid through their skin. The liquid hardens around them to form a shell. 23

Micro-Fact The word gastropod means “stomach foot.” Most gastropods have a strong foot that they use to move along surfaces.

Protozoa Let’s take a look at some protozoa that you would find in the ocean. They are all microscopic, most of them have just one cell, and many of them live as zooplankton.

Ciliates Vorticella are attached ciliates. You can see the cilia of this Vorticella around its mouth opening.

Ciliates all have hairs called cilia in one form or another. The short hairs often cover the whole body. They are used for swimming and for waving food toward the ciliate. Some ciliates are not free-swimming. Instead they attach themselves to algae or a rock. Vorticella look like little bells at the end of stalks attached to a surface. The bell shape is actually a tiny home, called a lorica, that keeps the creature safe inside. The stalks can contract like springs, drawing the Vorticella down to its base if it is disturbed. 2

Amoebas with shells Amoebas are found in all kinds of water. Many amoebas look like blobs of jelly, but marine amoebas, such as radiolarians and foraminifera, are often encased in a kind of shell called a test. Foraminifera tests look like beautiful, smooth sculptures under the microscope. Most foraminifera live near the ocean surface.

How Small Is Small? Several foraminifera tests would fit on the head of a pin.

When foraminifera die, they drift to the bottom of the ocean. Their tests get covered up, and eventually they become part of the ocean floor. The preserved remains of foraminifera, called fossils, can be millions of years old.

25

When we view radiolarian tests, or shells, with a microscope, we can see their shapes and patterns.

Larvae As we learned earlier, some marine animals are microscopic in their larval stage. They live among other zooplankton, feeding on phytoplankton or on creatures smaller than themselves. With their transparent bodies and tiny size, they look more like copepods or protozoa than their adult selves.

1 These zooplankton are all larvae of larger animals. See if you can match the larvae with the adults opposite. The answers are on page 31.

5

2

3

 26

crab

fish

octopus

starfish

squid 27

Size and Scale In this book, we measure some things in millimeters and even smaller measurements. This is because inches are just too big for measuring microorganisms and microscopic parts of things. Millimeters are pretty small, and micrometers and nanometers are so tiny that they are impossible to see with the naked eye and hard to imagine. There are more than 25 million nanometers in just one inch! 1 inch = 25.4 millimeters 1 millimeter = 1,000 micrometers or 1,000,000 nanometers 1 micrometer = 1,000 nanometers Only the smallest of microorganisms are measured in nanometers. Some of these, such as the tiniest bacteria and archaea, have to be magnified thousands of times before we can see them. Other microorganisms are huge compared to bacteria and archaea, but we still need to magnify them to see them clearly.

About Microscopes Many of the images you have looked at were produced using an electron microscope. Electron microscopes can magnify things hundreds of thousands of times, so they are used to magnify archaea and bacteria. They are also used for some of the amazing close-up images of marine microorganisms we’ve seen. At home or in school, we use optical microscopes. They usually magnify things anywhere between 20 and 1,000 times, depending on the lenses used. It’s always fun to take an everyday object, like a grain of sand or a drop of water, and look at it under the microscope. 28

Micro-Detective .

Marine Shapes If you look back at all the microorganisms you have learned about, you will see many amazing forms. Diatoms, dinoflagellates, radiolarians, foraminifera, larvae, and shelled gastropods come in all kinds of wonderful shapes. These radiolarians were drawn by scientists on an ocean expedition more than one hundred years ago as a record of what they found. You can find many more pictures of microorganisms in the library and on the Internet. Find as many marine microorganism shapes as you can, draw them, and cut them out. Use a large sheet of blue paper to create an ocean background. Then stick on your collection of microorganisms to create a microscopic marine mural.

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Glossary algae—protists that are similar to plants archaea—organisms with only one cell and similar to bacteria bacteria—microorganisms with only one cell that are the smallest and most numerous life-forms on Earth carbohydrate—sugars or starches that provide energy for plants and animals and are an important part of cells in all living things carbon—element that is present in the air, in all livings things, and in many minerals cell—tiny unit that all livings things are made of crustacean—type of animal that has a hard exterior skeleton cyanobacteria—type of bacteria that lives in strands or clumps and resembles plants and algae decomposer—organism that breaks down organic matter, releasing nutrients into the soil, water, or air hydrothermal—having to do with hot water that comes from underground, such as a hot spring on land or vent in the ocean floor larva—stage of an insect after it has hatched from an egg but is not yet an adult marine—having to do with, or from, the ocean microanimal—tiny bug or other animal too small to be seen clearly without a microscope microbe—microorganism that is not a microanimal, such as bacteria or archaea micrometer—measurement of length that is one-thousandth of a millimeter microorganism—any living thing that is too small to be seen properly without a microscope mineral—basic solid substance, such as calcium nanometer—measurement of length that is one-millionth of a millimeter nucleus—part of a cell that controls the cell’s form and functions 30

nutrient—substance that is a building block for living things and helps them grow and stay healthy organism—any living thing, such as a plant, animal, or bacterium photosynthesis—process by which plants and algae use sunlight to combine carbon dioxide and water to make food phototroph—organism that uses photosynthesis to make energy phytoplankton—plankton that are plant-like plankton—small and microscopic organisms that float on or near the ocean surface prey—hunt and catch living things for food, or a living thing hunted or caught by another for food protozoa—protists that are similar to animals virus—microbe that can only multiply by infecting living cells zooplankton—plankton that are animal-like

Explore These Web Sites Marine Microorganism Portrait http://www.microscopy-uk.org.uk/mag/artfeb02/ artwork.html Click on each of the marine microorganisms in this group portrait to find out more about them. MicroAngela’s Electron Microscope Image Galley http://www5.pbrc.hawaii.edu/microangela/index.html Find beautiful photos and fun information about marine microorganisms and other kinds of microscopic life. Answers to quiz on pages 26–27 1. octopus 2. starfish 3. fish 4. squid 5. crab 31

Index algae, 14, 15, 24 colors, 14, 15 size of, 14 amoebas, 18 shelled, 25 amphipods, 21 animals, 4, 5, 6, 7, 9, 11, 18, 19, 20, 26, 27 archaea, 11, 28 bacteria, 8, 9, 10, 11, 12 size of, 8, 28 see also cyanobacteria carbon cycle, 15 carbon dioxide, 7, 13, 15 cells, 9, 11 algae, 15 bacteria, 8, 9, 11 cyanobacteria, 12 phytoplankton, 17 protozoa, 18, 24, 26 chlorophyll, 14 ciliates, 24 coccolithophores, 16–17 copepods, 20–21, 26 crustaceans, 4, 7, 11, 19, 20–21, 26, 27 cyanobacteria, 12–13, 15 coccoids, 12 Prochlorococcus, 13 trichomes, 12

decomposers, 8 diatoms, 9, 16, 18, 29 dinoflagellates, 17, 29 extremophiles, 11 fish, 7, 19, 21, 26, 27 food, 6, 7, 8, 12, 24 food chain, 7 food web, 6, 7, 8 foraminifera, 25, 29 fossils, 25 gastropods, 23, 29 hydrothermal vents, 10, 11 larvae, 18, 19, 26, 29 microanimals, 18, 19 microbes, 9 at hydrothermal vents, 10–11 micromollusks, 22–23 microorganisms, 4, 10, 29 importance of, 5, 6, 8 measuring, 28 microscopes, 5, 16, 25, 28 mollusks, 22, 23, 26, 27 nutrients, 8, 17 oxygen, 13, 15

32

parasites, 21 photosynthesis, 7, 12, 13, 14 phototrophs, 12, 13, 16, 17 phytoplankton, 6, 7, 8, 12, 13, 26 in Earth’s cycles, 15 plankton, 4, 5, 9, 20, 22 glowing, 4, 17 types of, 5, 6, plants, 4, 5, 6, 7, 8, 9, 11, 14, 16 prey, 7, 18, 20 protozoa, 18, 24–25 radiolarians, 25, 29 red tides, 17 reproduction in algae, 15 in bacteria, 8 in protozoa, 18 salp, 21 sand, 20, 23, 28 seaweed, 14 shells, 22, 23, tests, 25 snails, 19, 22 viruses, 9, 11 worms, 19 zooplankton, 6, 7, 18–19, 20, 26