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A Survey of Life in the Sea - Introduction

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1 A Survey of Life in the Sea - Introduction
Choose to view chapter section with a click on the section heading. A Survey of Life in the Sea - Introduction The Linnaeus Classification System Prokaryotes – Small Yet Vital Eukaryotes – Diversity of Body Forms Chromalveolates – Dinoflagellates, Coccolithophores, Diatoms and Brown Algae Marine Plants: Red Algae, Green Algae, Seagrasses and Mangroves Rhizaria: Foraminiferans and Radiolarians Chapter Topic Menu

2 Survey of Life in the Sea - Introduction
Chapter 5 Pages 5-3 to 5-5

3 A Survey of Life in the Sea - Introduction
Chapter’s 5, 6 and 7 survey life in the sea. Chapter 5 overviews the classification system, prokaryotes, eukaryotes chromalveolates, marine plants and rhizaria. Chapter 6 overviews invertebrates - animals without backbones. Chapter 7 overviews vertebrates - animals with backbones. Survey of Life in the Sea - Introduction Chapter 5 Pages 5-3 to 5-5

4 A Survey of Life in the Sea - Introduction
Few people realize how diverse life is on planet Earth. Scientists have classified about 2 million species. It is estimated that there are between 5 to 100 million possible species on Earth. New species are discovered with regularity. What is the importance of any one species? Survey of Life in the Sea - Introduction Chapter 5 Pages 5-3 to 5-5

5 Imagine Classifying the Variety of Organisms
Survey of Life in the Sea - Introduction Chapter 5 Pages 5-3 to 5-5

6 The Linnaeus Classification System - Putting Life in Its Place
Chapter 5 Pages 5-5 to 5-15

7 The Need for Classification
Three reasons for classifying organisms: It helps identify the relationships between organisms. It requires scientists to clearly identify key characteristics of each organism. It avoids confusion. Common names differ with cultures. Scientists in the US and Japan can identify exactly what they are both talking about by using the species’ Latin name. Common names are avoided in science. The Linnaeus Classification System Chapter 5 Pages 5-5 to 5-6

8 The Need for Classification
The same common name may apply to two different organisms. Scientists avoid the problems with common names by assigning every species its own Latin name. These photos are different animals. The common name for both is “Dolphin.” But, it’s a Dolphin “fish” and a Dolphin “mammal.” The Linnaeus Classification System Chapter 5 Pages 5-5 to 5-6 Coryphaena hippurus Tursiops truncatus

9 Classification Taxa In 1758, Carolus Linnaeus laid the framework for the classification system we use today. Linnaeus used Latin for organism’s names since that was the common language of science at the time. Latin is used for two main reasons: Tradition It’s a neutral language - no one culture need feel slighted because scientific names are in another scientist’s native language. The Linnaeus Classification System Chapter 5 Pages 5-7 to 5-9

10 Arctic Krill Euphausia superba
Classification Taxa An organism’s scientific name represents two taxa. They are: Species – is the most specific of the taxa. Species is usually considered to be a group of organisms that can reproduce together. Genus – is the taxon above species. Genus grouped species are considered to be closely related. Example, there are 34 species of reef shark belonging to genus Carcharhinus. The Linnaeus Classification System Chapter 5 Pages 5-7 to 5-9 Arctic Krill Euphausia superba

11 Classification Taxa Scientists identify each species by referring to both the genus and the species. The genus is capitalized and the species name in lower case. You also italicize or underline scientific names. The Linnaeus Classification System Chapter 5 Pages 5-7 to 5-9 Bull Shark Carcharhinus leucas Gray Reef Shark Carcharhinus amblyrhynchos

12 Pilot Whale Globicephala melas
Classification Taxa A scientific name is a binomial name - from Latin bis meaning twice and nomen meaning name. Each organism has a unique scientific name. The Linnaeus Classification System Chapter 5 Pages 5-7 to 5-9 Pilot Whale Globicephala melas

13 Classification Taxa There are eight main taxa into which scientists classify organisms (from the general to specific): Domain - Fundamental groups of living organisms based on the genetic and physical structure of individual cells. Kingdom - (or supergroups) a group of similar phyla. Phylum - (or division) - a group of Classes. Classes - are groups of related Orders. Orders - groups of related Families. Families - groups of Genera that share characteristics. Genus - (plural Genera) groups species that are closely related. Species - the Latin name for an individual organism. The Linnaeus Classification System Chapter 5 Pages 5-7 to 5-9

14 Classification Taxa The Linnaeus Classification System
Chapter 5 Pages 5-7 to 5-9

15 Classification Taxa The Linnaeus Classification System
Chapter 5 Pages 5-7 to 5-9

16 Determining Taxa How organisms are classified:
Originally by using anatomical features. The prevailing view now is that taxonomy generally reflects theoretical evolutionary relationships. Classifying by anatomical features remains an important classification method. However, the study of genetics has become more important. The Linnaeus Classification System Chapter 5 Pages to 5-12

17 Determining Taxa A common problem taxonomists have in classifying organisms is that some organisms don’t fit neatly into defined classifications. An organism can have characteristics that fit in one and others that separate it from that same classification. The answer is to insert intermediate classification levels. By assigning super or sub levels to create new higher or lower divisions within a classification. Intermediate classifications may sometimes have two names. For example, one taxonomist may use the division subphylum, while another uses the division superclass. The Linnaeus Classification System Chapter 5 Pages to 5-12

18 Determining Taxa The Linnaeus Classification System
Chapter 5 Pages to 5-12

19 The Three Domain System of Classification
Taxonomic studies have lead to the development of a system of classification. They divided all life-forms (except viruses) into several kingdoms. Division into kingdoms is still argued among scientists. Today, most taxonomists divide all life on Earth into three domains - Archaea, Bacteria, and Eukarya. The Linnaeus Classification System Chapter 5 Pages 5-13

20 Viruses - The Tiniest Fragments of Life
The smallest forms of what could be considered marine life are viruses. Unlike other organisms, viruses have no metabolism or cell structure of any kind. Viruses are simply strands of DNA or RNA in a protective coat. Despite their small size, it has been calculated that the ocean contain hundreds of millions of tons of viruses. The biomass of marine viruses may be greater than that of all marine mammals. They are the most common biological agent in the sea. The Linnaeus Classification System Chapter 5 Pages 5-13

21 Phylogenetic Tree of Life
The tree is a visual representation of how organisms fit with one another. It shows the theorized evolutionary relationships among various species that are thought to have a common ancestor. The Linnaeus Classification System Chapter 5 Pages 5-14

22 Prokaryotes - Small Yet Vital
Chapter 5 Pages to 5-20

23 Old and Simple Most life in the ocean exists as microbes and minute organisms. The prokaryotes (from the Latin, pro meaning before and the Greek, karyon meaning kernal, nucleus) are important oceanic micorbes. In the world’s ocean they number more than 3 x1028. This is an almost unimaginable number – more than 100 million times as great as the number of stars in the visible universe. Prokaryotes – Small yet Vital Chapter 5 Pages to 5-17

24 Old and Simple Domain Bacteria and Archaea are classified as prokaryotes because they’re structurally far simpler than the cells found in the organisms of the domain Eukarya. They: Lack chromosomes or a nucleus. Do not have mitochondria. Lack chloroplasts, but accomplish photosynthesis. Photosynthesis by prokaryotes is accomplished by having chlorophyll molecules in its membranes. They are the smallest organisms. Prokaryotes – Small yet Vital Chapter 5 Pages to 5-17

25 Old and Simple It is theorized that the process of photosynthesis evolved with these early prokaryotes. It is thought that prokaryote cells had a endosymbiotic relationship within other cells. Some prokaryotes are extremophiles – organisms that live in environments fatal to most forms of life. Prokaryotes – Small yet Vital Chapter 5 Pages to 5-17

26 Archaea and Bacteria Genetic work has clearly separated bacteria and archaea into two different domains - although both are prokaryotes. Archaea (from the Greek archaio meaning old) are extremely common in the ocean – they dominate the life of many deep-sea open ocean areas. Archaea includes many extremophiles. Archaea live near deep hydrothermal vents, in high salinity pools, in highly acidic environments, in sulfur pools, and even close to volcanoes. Prokaryotes – Small yet Vital Chapter 5 Pages to 5-20

27 Archaea and Bacteria Scientists continue to find new and diverse bacteria. Bacteria are extremely adaptable and capable of processes that no other organisms can accomplish. One important example is a species of bacteria that creates organic nitrogen compounds by fixing inorganic nitrogen from the air. These organic nitrogen compounds are essential to most forms of life. Prokaryotes – Small yet Vital Chapter 5 Pages to 5-20

28 Archaea and Bacteria There are hundreds of thousands of bacteria species, one important group are Cyanobacteria (from the Greek kyan meaning dark blue). Cyanobacteria are: Crucial to life - important to nitrogen cycle and are primary producers. Cyanobacteria are extremely abundant. Perhaps the most plentiful species on Earth. Prokaryotes – Small yet Vital Chapter 5 Pages to 5-20

29 Eukaryotes - Diversity of Body Forms
Chapter 5 Pages to 5-22

30 Domain Eukarya – Major Groups
Domain Eukarya includes protists (mostly microbial eukaryotes, including those eukaryotes that aren’t a plant, animal or fungus), fungi, plants and animals. Eukaryotes are all organisms with cells organized into complex structures enclosed within membranes. All organisms in this domain have cells that have a nucleus. It is the presence of a nucleus that defines the members of domain Eukarya. “Eukarya” comes from the Greek eu, meaning good or true, and karyon meaning kernal, nucleus. Eukaryotes – Diversity of Body Forms Chapter 5 Pages to 5-22

31 Domain Eukarya – Major Groups
Eukaryotic cells are typically larger than prokaryote cells. Besides having a distinct nucleus, eukaryotic cells also have a variety of complex internal membranes and structures that prokaryotes do not. Eukaryotic animal and plant cells also differ from each other. Plant eukaryotic cells have a cell wall for rigid structural support and protection. Many have chlorplasts allowing them to perform photosynthesis. Animal Eukaryote cells do not have these structures. Eukaryotes – Diversity of Body Forms Chapter 5 Pages to 5-22

32 Domain Eukarya – Major Groups
Eukaryote Animal Cell Eukaryotes – Diversity of Body Forms Chapter 5 Pages to 5-22

33 Domain Eukarya – Major Groups
Major Eukaryote Groups Eukaryotes – Diversity of Body Forms Chapter 5 Pages to 5-22

34 Chromalveolates - Dinofagellates, Coccolithophores, Diatoms and Brown Algae
Chapter 5 Pages to 5-30

35 Chromalveolates - Dinofagellates, Coccolithophores, Diatoms and Brown Algae
Chapter 5 Pages 5-23

36 Dinoflagellates Dinoflagellates are the second most productive group of primary producers, after diatoms. Dinoflagellates are: Mostly marine and unicellular. Have a flagella for swimming. Microplankton. Both autotophic and heterotrophic. Some species are bioluminescent. Some species can cause Harmful Algal Blooms (HABs). Chromalveolates Chapter 5 Pages to 5-25

37 Dinoflagellates Some are symbiotic organisms called zooxanthellate.
These species live in the tissues of corals, anemones, giant clams and some species of sponges. Without these symbiotic species of dinoflagellates, most hard corals could not exist as we know it. They provide their hosts food via photosynthesis. The hosts provide the dinoflagellates with nitrogenous wastes. Chromalveolates Chapter 5 Pages to 5-25

38 Coccolithophores Coccolithophores all live in the upper layers of the ocean. Coccolithophores are: Unicellular. Autotrophic. Surrounded by extremely tiny plates made of calcium carbonate for protection - called coccoliths. Are numerous in some waters. A leading calcium carbonate producer in the ocean. Chromalveolates Chapter 5 Pages to 5-26

39 Diatoms Diatoms are: In the phylum Heterokontophyta that also includes brown algae. Single celled algae. The most productive phytoplankton. Basically dormant during winter months - in the spring they reproduce rapidly. Known for their cellular beauty and have a two-part silicon shell. A cause of Harmful Algal Blooms (HABs). Chromalveolates Chapter 5 Pages to 5-27

40 Brown Algae Brown algae:
Are in the same group as diatoms, but are structurally complex. Are multicellular. Range in size, with some individuals being gigantic. Have adapted to a variety of habitats. Can be found in tidepools and deep, near-shore waters. Prefer predominately cold water with lots of nutrients. Chromalveolates Chapter 5 Pages to 5-30

41 Brown Algae Many brown algae species have
Holdfasts – anchor the algae to the bottom. Leathery stipes – provide support like plant stems, but with no vascular system. Blades – equivalent of leaves. Pneumatocysts – gas filled float structures that lift the algae off the bottom and keep the blades close to the surface and sun. Chromalveolates Chapter 5 Pages to 5-30

42 Brown Algae Gets its distinctive olive-green/brown color from the pigment fucoxanthin. Kelp is the largest of the brown algae. Kelp is important because it is the foundation for many temperate coastal ecosystems. Chromalveolates Chapter 5 Pages to 5-30

43 Brown Algae Sargassum, another brown algae can be found drifting in North Atlantic currents. Early mariners feared that sargassum could ensnare their ships, though such dense concentrations are rare. The Sargasso Sea exists in a relatively currentless portion of the Atlantic. Chromalveolates Chapter 5 Pages to 5-30

44 Marine Plants - Red Algae, Green Algae, Seagrasses and Mangroves
Chapter 5 Pages to 5-38

45 Marine Plants – Red Algae, Green Algae, Seagrasses and Mangroves
Chapter 5 Pages 5-31

46 Phylum Rhodophyta – Red Algae
Are in the Phylum Rhodophyta. Consists of freshwater and marine algae. Are multicellular macro algae. Have chlorophyll a, but not b. Has red pigments called phycoerythrins - they allow some red algae to live much deeper than any other algae. Marine Plants Chapter 5 Pages to 5-33

47 Phylum Rhodophyta – Red Algae
Red algae species that live on coral reefs secrete a calcium carbonate shell. Their secretions bond coral colonies and debris together which in turn holds the reef together. Marine Plants Chapter 5 Pages to 5-33

48 Phylum Chlorophyta – Green Algae
Is in the Phylum Chlorophyta. Is made up of the macro algae. Shares the same green color as land plants. Has Chlorophyll a – a pigment directly involved with photosynthesis. Has Chlorophyll b – assists chlorophyll a in capturing light for use in photosynthesis. Consists of approximately 7,000 species. Marine Plants Chapter 5 Pages to 5-34

49 Phylum Chlorophyta – Green Algae
Scientists think the presence of chlorophyll a and b has evolutionary significance. It may indicate that land plants evolved from green algae. Green algae and land plants also have other pigments in common and have cell walls made of cellulose. Marine Plants Chapter 5 Pages to 5-34 Sea Lettuce

50 Marine Flowering Plants - Underwater Meadows and Shallow Nurseries
Few flowering plant species live in the marine environment - only about 200 species. These marine flowering plants play a surprisingly important role in the health of the ocean. Marine Plants Chapter 5 Pages 5-34

51 Plant Adaptation to the Marine Environment
Salinity in the water is the greatest challenge to which plants must adapt. Salt causes dehydration in plants. Marine plants resist dehydration through several adaptations such as waxy coverings or other protection that reduces water loss and prevention of dehydration. Marine Plants Chapter 5 Pages 5-34

52 Submergent and Emergent Plants
Submergent plants live entirely underwater – seagrasses for example. Emergent plants live with their roots underwater, but with a significant portion of the plant growing above the surface – mangroves for example. Marine Plants Chapter 5 Pages 5-35

53 Seagrasses Other than producing food and oxygen, marine plants provide important habitats for other marine organisms. Marine Plants Chapter 5 Pages to 5-36

54 Mangroves Mangrove swamps are important to the environment:
They act as nurseries for adjacent marine ecosystems. They filter runoff water protecting sensitive offshore ecosystems that would be harmed or killed by settling sediment. They hold sediments in place. They slow waves and reduce erosion while retaining nutrients used by organisms living there. Marine Plants Chapter 5 Pages 5-37

55 Rhizara - Foraminiferans and Radiolarians
Chapter 5 Pages to 5-41

56 Rhizara - Foraminiferans and Radiolarians
Rhizaria: Are a species-rich eukaryote supergroup that includes Foraminifera and Radiolaria. Are microscopic and amoeboid in form. Secrete external shells/skeletons. Rhizara - Foraminiferans and Radiolarians Chapter 5 Pages to 5-41

57 Rhizara - Foraminiferans and Radiolarians
Live as plankton, most live on the sea bottom. Can be found in very deep water. Secrete elaborate external shells (tests) of calcium carbonate. Rhizara - Foraminiferans and Radiolarians Chapter 5 Pages to 5-41

58 Rhizara - Foraminiferans and Radiolarians
Are exclusively marine zooplankton. Mostly live in the photic zone. Secrete intricate external skeletons. Rhizara - Foraminiferans and Radiolarians Chapter 5 Pages to 5-41


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