CLASSIFICATION & THE TREE OF LIFE

WHAT ARE THE CHALLENGES TO LIVING IN THE SEA?Maintaining Homeostasis through -

Salinity

Diffusion & Osmosis – moving from an area of high concentration to an area of low concentration

Active Transport- moving from an area of low concentration to an area of high concentration

Regulating Salt & Water Balance

Osmoconformer: internal concentrations change as the salinity of the water changes; many organisms can only live in a narrow range of salinity; there are a few others that can tolerate relatively large changes in salinity

These organisms have limits & experience osmotic problems outside their range of tolerance

Since many of these organisms live out in the open ocean, there aren’t many issues

WHAT ARE THE CHALLENGES TO LIVING IN THE SEA?

Osmoregulators: control their internal concentrations to avoid problems; these organisms still have limits but can adapt better than others – they adjust the concentrations of solutes in their body fluids so that the concentration of their fluids match their environment

It DOES NOT matter if there are the same dissolved chemicals as long as the TOTAL AMOUNT of dissolved materials is the same

Sometimes its only ONE chemical that they change

Example: Sharks typically only change the amount of urea in their bodies

WHAT ARE THE CHALLENGES TO LIVING IN THE SEA?

TemperatureOrganisms are greatly affected by temperature; metabolic reactions speed up in higher temperatures & slow down drastically as it gets cold

Most reactions occur 2x as fast with a 10oC rise in temperature; at extreme temps, most enzymes will cease to function; most organisms are adapted for living within a particular temp range

WHAT ARE THE CHALLENGES TO LIVING IN THE SEA?Organisms are classified based on their metabolic reaction rate

Ectotherms - “cold-blooded” organisms; heat is quickly lost to the environment & doesn’t change the body temperature

Poikilotherms - body temperature & metabolic rates change with the temperature of the surroundings (includes some endotherms - shark & tuna); these organisms slow down as temperature decreases

Endotherms - “warm-blooded” organisms; metabolic heat is retained & raises the body temperature above the surroundings (mammals, birds, some large fish (tuna & sharks)

Homeotherms - organisms with the ability to regulate their internal temperature so that it stays even with the external temperature; retain heat & control their metabolism by burning fats & energy-rich molecules; they remain highly active regardless of water temperature -eat more that poikilotherms; most have blubber, feathers, or hair though to help insulate and reduce this amount

WHAT ARE THE CHALLENGES TO LIVING IN THE SEA?

Surface to Volume RatioAmount of surface area relative to the total volume of an organism

Determines how rapidly heat & materials (nutrients, waste products, & gases) flow through the organism, typically across the surface of the organism

Size is the main determining factor - as organisms grow larger, their volume increases faster than their surface area

Small organisms have a larger S/V ratio, which means they can rely on simple diffusion across their surfaces to exchange materials

Larger organisms have a smaller S/V ratio & must develop supplementary mechanisms, like respiratory & excretory systems

WHAT ARE THE CHALLENGES TO LIVING IN THE SEA?

Reproductive StrategiesSome species release millions of eggs & sperm into the water, where fertilization occurs & have no further interaction with their offspring - known as BROADCAST SPAWNING (corals)

Some species only have a few offspring & invest a lot of time & effort into them (whales)

Some species develop from larval stages & look differently from egg to adult (jellyfish)

Can be asexually or sexually

Sexually reproducers can be male/female in separate individuals or hermaphroditic

TREE OF LIFE

Charles Darwin’s version

The New Tree of Life (updated 4/11/2016)

PROKARYOTESSmallest & structurally simple organisms

Carryout nearly ALL chemical processes that eukaryotes do plus those that are unique to prokaryotes

Enclosed by a cell wall

Single-celled

Lack nucleus & membrane-bound organelles

Contain circular DNA

The Usual Suspects:

Domain Bacteria [Eubacteria]

Domain Archaea [Archaeabacteria]

FEEDING PROKARYOTES

Autotrophs

“Self-feeders”

Make their own organic compounds Photosynthetic/Photoautotrophic - contain chlorophyll to trap light energy (no chloroplasts); account for the majority of the primary production in the ocean; some even use the glow of hydrothermal vents; some produce S instead of O2

Chemosynthetic/Chemoautotrophic - derive energy from chemical compounds like H2S, S, N, & Fe (hydrothermal vent smoke)

Classified as “Primary Producers”

FEEDING PROKARYOTES

Heterotrophs“Different -feeders”

Obtain energy through cellular respiration

Cannot make their own food, must obtain it from other organisms

Many are decomposers

Nitrogen-Fixers

Convert gaseous N2 into ammonium to be used as a nitrogen source for primary producers

Many are bottom-dwelling & planktonic cyanobacteria

DOMAIN BACTERIA [EUBACTERIA]

Branched early; very distinct from the other 2 branches

Abundant in ALL parts of the ocean

Stiff or slimy coverings on the cell wall (thick) to allow them to attach to surfaces or act as a protector

Can range in sizeVery Small - 250,000 can fit on a period .

Larger (0.02 in) found in intestines of coral reef fish

In larger numbers they can appear as white hairs on rotting seaweed or pink patches in stagnant mudflats or saltmarshes

DOMAIN BACTERIA [EUBACTERIA]

Grow in extremely high numbers in favorable environmentsExample - Detrius (dead organic matter)

Decay bacteria breakdown wastes & detritus then release nutrients back into the environment; this is vital to life on Earth to ensure the recycling of essential nutrients

Most abundant form of life on Earth = Pelagibacter ubique (found in open ocean waters)

Can reproduce quickly, some in 20 minutes (binary fission, a type of asexual reproduction)

DOMAIN BACTERIA [EUBACTERIA]Types/FormsSome play a vital role to feed bottom-dwelling animals

Some degrade oil & toxic pollutants that enter the environment

Some cause disease in marine animals & humans

Cyanobacteria (blue-green algae) is a group of photosynthetic bacteria (can also appear red)

1st photosynthetic organisms on Earth

Thought to play an important role in the accumulation of O2 in the atmosphere

Can live in hairs of polar bears, in calcareous rocks & coral skeletons, and along rocky coasts

Planktonic species reproduce rapidly & change color of water - create “red tides”

Epiphytes live ON algae or marine plants, while Endophytes live INSIDE algae

SPIRILLABACILLI

COCCI

DOMAIN BACTERIA [EUBACTERIA]Major Forms:

Nostoc Spirulina Oscillatoria Fisherella

DOMAIN ARCHAEA [ARCHAEABACTERIA]

Simplest, most primitive life forms

Look similar to the oldest fossils

Estimated to be 3.8 billion years old

Important role in early evolution of life

More closely related to eukaryotes than bacteria

DOMAIN ARCHAEA [ARCHAEABACTERIA]

Found in extreme environments - hot sulfur springs, saline lakes, & highly acidic/alkaline environments

Named “extremophiles” or “lovers of extremes” - but it is not true of all species

Survive pressures of 300 to 800 atmospheres

Types/FormsSome live at hydrothermal vents

Some live in coastal salt plains or deep ocean basins, where it’s extremely salty

EUKARYOTES

Can be either unicellular or multicellular

Contain a nucleus & membrane-bound organelles

DNA is within nucleus & contains chromosomes

Cellular Respiration occurs in mitochondria Respiration is the breakdown of organic molecules into energy

Many contain cilia or flagella

For movement

To push water or particles into or over bodies

DOMAIN EUKARYA [PROTISTA]General term of this group is ALGAE

Mostly aquatic & photosynthetic, but unicellular

Color is a result of pigments & their concentration

Lack flowers, true leaves, stems, & roots; have simple reproductive systems

Multicellular seaweeds technically fall under this group since they lack the specialized tissues of plants

Not considered to be it’s own Kingdom anymore since so many of it’s characteristics are shared

Examples:

Diatoms

Dinoflagellates

Silicoflagellates

Coccolithiophorids

Cryptopyhtes

DIATOMS [PHYLUM HETEROKONTOPHYTA]

Unicellular, but form aggregate into chains or star-like groups

Enclosed by cell walls made of silica, a glass-like material

Glassy shell is called a frustule, which is similar to two tightly fitting halves (like a box)

Has perforations & ornaments (spines or ribs), that allow light to pass through for photosynthesis and dissolved gases & nutrients to enter & exit

Store food as oil instead of starch

Color is a yellowish-brown, due to carotenoid pigments in chlorophyll a & c (called “golden algae”)

Important open-water primary producers in temperate & polar regions

The large number of diatom cells in the ocean accounts for a large share of the organic carbon & oxygen produced on Earth

Over half of the estimated 12,000 species are marine, most of which are planktonic

Reproduce through cell division

DIATOMS [PHYLUM HETEROKONTOPHYTA]

DIATOMS [PHYLUM HETEROKONTOPHYTA]

Favorable environmental conditions (adequate nutrients & light) trigger periods of rapid reproduction, known as “blooms”Most get significantly smaller in size, due to cell division & a depletion in the silicate from water the growing population

Glassy frustules of dead diatoms settle to the bottom of the ocean & form thick deposits of siliceous material (biogenous sediments) that is known as diatomaceous ooze

This material is found fossilized in various parts of the world, known as diatomaceous earth and is mined & used in products such as pool filters, temperature & sound insulators, & mild abrasives in toothpaste and bathroom cleaners

DINOFLAGELLATES [PHYLUM PYRROPHYTA]

“Plant-like”, microscopic algae

Contain 2 flagella, thick cell wall plates of cellulose(can have spines or pores)

Most are photosynthetic, but can ingest food particles

Some have a light sensitive pigment spot, that acts as a “crude eye”

There are over 1,200 marine species

Stands for “Fire Algae”

Ceratium

DINOFLAGELLATES [PHYLUM PYRROPHYTA]

Important planktonic primary producer in warm waters

Reproduce by simple cell division

Sometimes will form “blooms” that color the water red, reddish-brown, yellow, or other colors

Some (especially the red forms) release toxic substances that taint the seafood collected during that time and make it poisonous

Others are noted for their ability to bioluminesce

This is only seen at night along the sea surface

They are especially bright if the water is disturbed by a boat or when waves crash on shore

DINOFLAGELLATES [PHYLUM PYRROPHYTA]

Symbiotic RelationshipsMutualism -Zooxanthellae live within sponges, coral reefs, sea anemones, & giant clams; they fix CO2 by photosynthesis, release organic matter used by the coral, & help in the formation of the coral skeleton

Parasitism -Pfiesteria or “phantom dinoflagellates” reside as cysts in sediments; blooms are triggered by coastal pollution which causes deadly open sores on fish, crabs, oysters, & clams

Major issue in the Chesapeake Bay area

Noctiluca

(Seasparkle)

RED TIDES

COCCOLITHOPHORIDS [PHYLUM HETEROKONTOPHYTA]

Another form of “golden algae” (like diatoms)

Flagellated, spherical shells covered with button-like structures called coccoliths (made of calcium carbonate)

Make up a large part of calcareous deposits in sediments of warm waters

DOMAIN EUKARYA [PROTISTA/PROTOZOAN]“Animal-like” protists, most are unicellular; classified by movement

“First animals”; considered “zooplankton”

Enormous diversity in structure, function, & lifestyle; 50,000 estimated species

Heterotrophic (eat like animals - engulf food)

Inhabit freshwater, saltwater, & the water inside other organisms

Found in sediments, surface of seaweeds, guts of animals, & plankton samples

Examples:

Foraminiferans

Radiolarians

Ciliates

RADIOLARIAN [PHYLUM SARCODINA]

Planktonic marine protozoans with shells made of silica; are spherical in shape with radiating spines

Thin, needle-like pseudopodia capture food

Remains of their shells settle to the bottom of deep water areas because their shells are more resistant to dissolving under pressure

FORAMINIFERAN [PHYLUM SARCODINA]

Marine protozoans with a shell made of calclium carbonate

Have long, thin, retractable pseudopodia; used to trap diatoms & other organisms suspended in water

Most species are known as “microfossils” - they can use the distribution of these to determine past water temperatures, where to look for oil, & tell the age of sediments

CILIATES [PHYLUM CILOPHORA]

Largest group of protozoans

Use cilia to move & feed

Many are found creeping over seaweeds & in sediments

Others live on the gills of clams, in the intestines of sea urchins, & on the skin of fish

Important to the open-water food web (microbial loop)

DOMAIN EUKARYA [FUNGI]

Mostly multicellular, with cell walls & cell membranes

Heterotrophic

500 known species of marine fungi

Mostly microscopic

Types/Forms

Most are decomposers & saprophytes (live on dead organisms)

Some are parasites of fish & plants, like seagrass or borers in mollusk shells

Some live in symbiotic relationships with algae or cyanobacteria to form lichens on rocky intertidal zones

DOMAIN EUKARYA [PLANTAE]

Primary producers

Majority composed of seaweed (multicellular algae), Seagrass, Kelps, & Mangroves

DOMAIN EUKARYA [THE SEAWEEDS]

Multicellular algae

Known as “macrophytes” or “macroalgae” rather than seaweed

Eukaryotic, but lack highly specialized structures & reproductive mechanisms; some people don’t classify them as plants, but as protists

Types are based on colors

DOMAIN EUKARYA [THE SEAWEEDS]Structure -Lack leaves, stems, & roots

Body is known as a thallus

Leaf-like flattened portions are blades; large surface area, where photosynthesis occurs (no veins)

Pneumatocysts (CO air-filled sacs) keep blades close to the water surface

Some blades originate from a stipe; a stem-like structure that provides support)

Holdfast, a structure that resembles roots, attaches to the thallus (kelps)

No roots or soft-bottom anchors; water & nutrients are picked-up directly across the surface of the thallus (no need for roots)

DOMAIN EUKARYA [THE SEAWEEDS]

DOMAIN EUKARYA [PHYLUM CHLOROPHYTA]

Green AlgaeFreshwater & terrestrial environments

10% of the 7000 species are marine (mostly unicellular)

Wide variety in bays, estuaries, & isolated tide pools on rocky coasts

Believed that land plants originated from these

Bright green thallus

Sometimes flourish in polluted areas

Enteromorpha

Ulva or Sea

Lettuce

DOMAIN EUKARYA [PHYLUM HETEROKONTOPHYTA, CLASS PHAEOPHYTA]

Brown AlgaeColor varies from olive green to dark brown (due to pigment fucoxanthin)

Almost all 1500 species are marine

Include the largest & most complex seaweeds (kelps)

Many can withstand exposure to air

This variety is used as a food source

DOMAIN EUKARYA [PHYLUM HETEROKONTOPHYTA, CLASS PHAEOPHYTA]

Brown Algae Types -Rockweeds are found on Atlantic & Pacific coasts

Knotted seaweed is found on Atlantic coasts

Sargasso Weed (think baby sea turtles floating around) is found in the Gulf of Mexico Have air bladders to keep it afloat

Most species grow on rocks, but two species float in large masses at sea

Kelp are found below low tide levels; provide food & shelter for many Many form fast growing intertwined stripes that are very dense & productive; known as Kelp Beds or Kelp Forests in the Pacific

DOMAIN EUKARYA [PHYLUM RHODOPHYTA]

Red AlgaeMore species than green & brown combined

Phycobilins (red filaments) mask chlorophyll

Most are red, but color can vary depending on exposure to light

Majority of the 4000 species are marine

Inhabit mostly shallow water environments

Gelidium

Gigartina

Rhodymenia

ECONOMIC IMPORTANCE OF SEAWEEDS

Food Source (red & brown)“Mariculture”- farming of seaweed in China, Japan, & Korea

Gelatinous Chemicals - “phycocolloids”(valuable due to their ability to form viscous suspensions or gels

Algin (from giant kelp) is used as a stabilizer in making ice cream & cheese; prevents icing from drying out; aids in emulsifying shampoo, shaving cream, plastic, & pesticides; used in making rubber, paint, paper, & cosmetics

Carrageenan (from red algae) is a jelly-like substance used to protect ham, fish, & other meats during shipping; used in laxatives & cosmetics; to grow bacteria

DOMAIN EUKARYA [PLANTAE]

True leaves, stems, & roots

Specialized tissue to transport water & nutrients

Found living submerged in seawater environments (seagrass) or in estuaries & along shores (mangroves & salt-marsh grasses),

DOMAIN EUKARYA [ORDER ALISMATALES]

SeagrassesOnly truly marine “plant” - often live submerged in seawater, rarely exposed at low tide

Resemble grass, but are not actually grasses (closest relatives are lilies)

Flowers are small & inconspicuous; pollen is carried (in strands) by water currents

DOMAIN EUKARYA [ORDER ALISMATALES]

TypesEelgrass is the mostly widely distributed variety (of the 60 known species) Temperate & tropical regions of the world

Found in shallow, well-protected coastal waters (estuaries & bays)

Common in oxygen-poor sediments

Zostera Highly productive; provide shelter & food for many organisms

Surf Grass Inhabits rocky coats, that are exposed to significant wave action

Found along the Pacific coasts

DOMAIN EUKARYA [FAMILY POACEAE: SALT MARSH GRASSES]

Cordgrass (Spartina sp.)True members of the grass family; not marine species, but adapted to living in salt

Do not tolerate total submergence in seawater

Live throughout temperate regions

Highly productive & provide habitat and breeding grounds for many fish species

Offer protection against erosion & provide natural water purification

Leaves are always partially exposed to air; salt glands in the leaves excrete excess salt

DOMAIN EUKARYA [FAMILY RHIZOPHORACEAE]

MangrovesTrees & shrubs adapted to living along tropical & subtropical shores

Land plants that can tolerate salt (like salt-marsh grasses)

Flourish along muddy or sandy shores, that are protected from waves

Adaptations allow it to live in areas where water loss from leaves is high & sediments are soft and poor in oxygen Thick leaves to prevent water loss

Seeds germinate while still attached to the tree