Chapter 12 Marine Life and the Marine Environment I 12 1 What Are Living Things and How Are They Classified a Introduction b A Working Definition of Life i Living things are classified based on their physical characteristics i A simple definition of life is that it consumes energy from its environment ii Several other qualities are crucial in defining life iii Water probably needs to be a part of a living organism because living things need a solvent for biochemical reactions iv A living thing probably has to have some sort of a membrane to distinguish itself from its environment v Most living things tend to respond to stimuli or adapt to their environment vi Lastly life as we know it is carbon based vii Life is a self sustained chemical system capable of undergoing Darwinian evolution c The Three Domains of Life i Bacteria Archaea and Eukarya ii Bacteria includes simple life forms with cells that usually lack a nucleus iii Archae is a group of simple microscopic bacteria like creatures that includes methane producers and sulfur oxidizers that inhabit deep sea vents iv Eukarya includes comples organisms multicellular plants multicellular animals fungi and protoctists which are a diverse array of mostly microscopic organisms that don t fit into any other group v What were the ancestors of these three domains of life 1 The are thought to have consisted of a community of early primitive 2 Groups coexisted and transferred cells through lateral gene transfer d The Five Kingdoms of Organisms i Kingdom Monera includes some of the simplest organisms 1 Single celled lack discrete nuclei a Cyanobacteria heterotrophic bacteria and archaea 2 These organisms are found throughout the breadth and depth of the cells oceans ii Kingdom Plantae comprises the multicelled plants all of which photosynthesize 1 Certain plants are vital parts of coastal ecosystems including mangrove swamps and salt marshes iii Kingdom Animalia comprises the multicelled animals 1 Range in complexity from the simple sponges to comples vertebrates iv Kingdom Fungi includes 100 000 species of mold and lichen less than one half including humans of 1 of them are sea dwellers 1 Fungi exist throughout the marine environment and are much more common in the intertidal zone 2 Other fungi remineralize organic matter and function primarily as v Kingdom Protoctista a diverse collection of single and multicelled organisms decomposers that have a nucleus Include various types of marine algae 1 2 Single celled animals called protozoa e Linnaeus and Taxonomic Classification i Today the systematic classification of organisms is called taxonomy and involves using physical characteristics as well as genetic information to recognize organism similarities ii The order is as follows 1 Kingdom 2 Phylum 3 Class 4 Order 5 Family 6 Genus 7 Species iii All organisms that share a common category have certain characteristics and evolutionary similarities iv The fundamental unit of taxonomic classification is the species 1 Consists of populations of genetic similarity 2 Individuals that share a collection of inherited characteristics whose combination is unique v Binomial Nomenclature is where everything is known by just two Latin names 1 Genus species 2 Often shortened by abbreviating the first word to just the first letter a G species 12 2 How Are Marine Organisms Classified II a Introduction i Marine organisms can be classified according to where they live and how they ii Organisms that inhabit the water column can be classified as either plankton or move nekton iii All other organisms are benthos b Plankton Drifters i Plankton include all organisms that drift with ocean currents Individuals organism is called a plankter 1 2 Plankters are not unable to swim 3 Plankton are unbelievably abundant and important within the marine environment 4 Most of Earth s biomass consists of plankton adrift in the oceans 5 98 of marine species are bottom dwelling 6 7 Types of Plankton the vast majority of Earth s biomass is planktonic a Plankton can be classified based on their feeding styles b Autotrophic an organisms capable of photosynthesis and therefore can produce its own food i Phytoplankton autotrophic plankton can range in size c Heterotrophic an organisms that cannot produce its own food and relies instead on food produced by other organisms i Zooplankton heterotrophic plankton include marine animals d Bacterioplankton much more abundant and far more widely distributed than previously thought i Oceanic bacterioplankton are likely the most abundant photosynthetic organism on Earth e Virioplankton plankton including viruses are an order of magnitude smaller than bacterioplankton and are similarly little known i They may limit the abundance of other types of plankton through infection 8 Plankton can also be classified according to the portion of their life cycle spent as plankton holoplankton a Organisms that spend their entire lives as plankton are b Many organisms that spend their adult lives as nekton or benthos spend their juvenile and or larval stages as plankton i These organisms are called meroplankton 9 Plankton can be classified based on size a Macroplankton large floating animals and algae between 2 and 20 centimeters b Picoplankton very tiny drifters between 2 and 2 microns c Nekton Swimmers i Nekton include all animals capable of moving independently of the ocean currents by swimming or other means of propulsion 1 Include most adult fish and squid marine mammals and marine reptiles as well as humans 2 Unable to move throughout the breadth of the ocean 3 Changes in temperature salinity viscosity and availability of nutrients effectively limit their lateral range 4 Water pressure normally limits the vertical range of nekton d Benthos Bottom Dwellers i The term benthos describes organisms living on or in the ocean bottom ii Epifauna live on the surface of the sea floor iii iv Nektobenthos live on the bottom yet also have the ability to swim or crawl Infauna live buried beneath the sand shells or mud through the water above the ocean floor v Moving across the bottom from the shore into deeper water the number of benthos species per square meter may remain relatively constant but the biomass of benthos organisms decreases vi Shallow coastal areas are the only locations where large marine algae attached to the bottom are found because these are the only areas of the sea floor that receive sufficient sunlight vii Where photosynthetic production cannot