Marine Life and
Adaptations to
the Marine
Environment
Overview
More than 250,000 identified marine species
 Most live in sunlit surface seawater
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Classification of living organisms
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Three domains of Life
 Archaea
 Prokaryotic, includes
“extremophile”
bacteria
 Bacteria
 Prokaryotic, includes
what used to be in
Kingdom Monera
 Eukarya
 Eukaryotic cells
 Includes Protists,
Fungi, Plants, and
Animals
Domain Archaea
Bacteria - Prokaryotic cells
 Cell wall differs from those bacteria in
Domain Bacteria
 Includes extremophile bacteria

○ Acidophiles
○ Halophiles
○ Thermophiles
○ Etc.
○ These bacteria are found to chemosynthesize in
hydrothermal vents
Domain Bacteria
Bacteria – prokaryotic cells
 Cell wall made of peptidoglycan
 Includes Staphylococcus, Bacillus,
Vibrio, Pseudomonas, etc.

○ Only a very small % of bacteria are
pathogenic
○ Bacteria are very important in things like
nitrogen cycle, decomposition, food making,
etc.
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Cyanobacteria are photosynthetic
bacteria
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Archaea and Bacteria
○ Most numerous organisms on Earth!!
- Think about how much bacteria lives just on you
- Viruses are thought to out number bacteria but if you
are just talking about “live” organisms then bacteria
are the most numerous
○ Simplest of organisms
- But, can live in every thinkable habitat, even those
once thought to be unsuitable to life, very successful
organisms!!

Now we will talk about Domain Eukarya
○ Includes protists, fungi, plants, animals
Domain Eukarya

Protists:
 Algae
○ Photosynthetic
○ Can be unicellular, colonial, or multicellular
- Multicellular - “seaweed” – kelp, sargassum, sea lettuce
- Unicellular – phytoplankton, produce majority of oxygen
in atmosphere comes from our phytoplankton, can cause
red tides (examples are dinoflagellates and diatoms)
 Protozoans
○ Heterotrophic
○ Unicellular
○ Amoeba, paramecium
Domain Eukarya
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Fungi
 Heterotrophic
 Secrete enzymes and absorb nutrition
 Since they are heterotrophic, they are more closely
related to animals than to plants
 Multicellular (mold) or unicellular (yeast)
Domain Eukarya

Plants
 Autotrophic, multicellular
 Many plant species cannot tolerate saltwater
○ Very few species grow in/near ocean
 Sea grasses
 Mangroves
 Dune plants
Domain Eukarya

Animals
 Heterotrophic, multicellular, have motility
at some point in life cycle
 Wide variety
○ From simplest of animals (sponges) to most
complex (mammals)
Viruses

Acellular entities
○ Are they “alive”??? – many scientists say no
○ Do not have the machinery for life processes,
have to take over host cell
○ The ultimate “parasites”
○ Viruses very prevalent in the marine
environment
Taxonomic classification
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Systemized classification of organisms
Kingdom
Phylum
Class
Order
Family
Genus
Species
 Fundamental unit
 Population of genetically similar, interbreeding
individuals

With new molecular methods (comparing
DNA sequence and amino acid sequences
of certain proteins), traditional taxonomy
is changing
○ Taxonomists are discovering new relationships
between species
○ Molecular data gives a clearer picture of
relatedness as opposed to the traditional ways
of classifying organisms:
- Morphology, embryology, behavior, habitat, etc.

Let’s take a closer look at Plant and
Animal taxonomy

Kingdom Plantae
○ Nonvascular Plants – mosses, etc
○ Vascular Plants
 Seedless Vascular Plants – ferns, etc
 Seed Vascular Plants
- Gymnosperms – “naked” seeds
- Angiosperms – flowering plants (in the marine
environment these include mangroves, sea
grasses, etc.)
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Kingdom Animalia
 Parazoa – no true embryonic tissues
○ Sponges
 Eumetazoa – true embryonic tissues
○ 2 true tissues – radial symmetry; Cnidarians,
Ctenophores
○ 3 embryonic tissues – bilateral symmetry; all
other animals
 Acoelomate – only flatworms
 Coelomates:
- Protostomes
- Deuterostomes
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Radially Symmetrical Animals, 2
true embryonic tissues
 Cnidarians
○ Class Anthozoa – sea anemones, corals
○ Hydrozoa – Hydra
○ Scyphozoa – “jellies”
 Ctenophores – no stinging cells,
complete gut unlike in the Cnidarians
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What are the embryonic tissue layers?
 Tissue layers that form during development
○ Ectoderm
○ Mesoderm
○ Endoderm
What is radial symmetry?
 What is bilateral symmetry?
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What is an acoelomate?
 What is a coelomate?
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Bilaterally symmetrical animals are divided
into 2 groups
 Protostomes – 1st blastopore that forms during
development becomes the mouth
○ Includes Annelids, Arthropods, Molluscs
 Deuterostomes – 1st blastopore that forms
during development becomes the anus
○ Includes the Echinoderms, Chordates
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Bilaterally symmetrical animals
 Platyhelminthes – flatworms
 Protostomes
○ Annelids
○ Mollusks
○ Nematods
○ Arthropods
 Deuterostomes
○ Echinoderms
○ Chordates
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Platyhelminthes – flatworms
 Class Turbellaria – free-living flatworms
 Class Trematoda – flukes
 Class Cestoda - tapeworms
http://ocean.nationalgeographic.com/ocean/photos/marine-worms/#/marine-worms03-flatworm_18260_600x450.jpg
Protostomes
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Mullusca
 Class Polyplacaphora - chitins
 Class Gastropoda – snails, conchs
 Class Bivalvia – oysers, scallops
 Class Cephalopoda – squid, octopus
Protostomes

Annelida
 Class Oligochaeta – earthworms
 Class Polychaeta – many marine species,
sand worms, feather dusters
 Class Hirudinea - leeches
Marine feather duster worm
http://www.aquariumdomain.com/viewMarineInvertSpecies.php?invert_marine_id=26
Protostomes

Nematoda – round worms
○ Many of these are parasitic
Protostomes
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Arthropoda
 Largest group of animals on the planet!!!!
 Chelicerates – horseshoe crabs and arachnids
 Crustaceans – marine and freshwater, crabs,
lobster, shrimp, barnacles
 Insects and relatives
Limulus polyphemus
Callinectes sapidus
Deuterostomes
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Echinodermata
 Adults have pentahedral symmetry but
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larvae are bilaterally symmetrical
Class Ophiuroidea – brittle stars
Class Echinodea – sea urchins
Class Holothuroidea – sea cucumber
Class Crinodea – sea lillies
Sea cucumber from IRL
Deuterostomes
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Chordata
 Characteristics: dorsal hollow nerve cord, notochord, post-anal tail,
pharyngeal gill slits
 Subphylum Urochordata – tunicates
 Larvae have bilateral symmetry, look like tadpole
 Subphylum Cephalochordata – lancelets
 Subphylum Vertebrata
○ Superclass Agnatha – jawless fishes
○ Superclass Gnathostoma – jaws
 Class Chondrichthyes
 Class Osteichthyes
 Class Amphibia
 Class Reptilia
 Class Mammalia
Vertebrates
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Class Chondrichthyes
 Sharks, rays
Vertebrates
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Class Osteichthyes
 Bony fish, ray-finned fish
 Great diversity in the ocean!
○ Very small to very large
○ Large tuna, grouper, sailfish
○ Deep sea fish
○ Flattened fish – flounder
○ Seahorses
○ Eels
Vertebrates
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Class Reptilia
 Includes birds now!!!
 Sea turtles, sea snakes, pelicans, penguins,
osprey, sea gulls
http://seaturtlesofindia.org/?page_id=12
Vertebrates
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Class Mammalia
 What are the characteristics of mammals?
 Carnivores: Sea otters, Polar bears, pinnepeds
(walruses, seals, sea lions)
 Sirenians: manatees
 Cetacea
○ Odontocetes – toothed whales: dolphins,
porpoises, sperm whale
○ Mysticetes: baleen whales: gray whale, right
whale, blue whale (largest animal to roam the
Earth)
Classification in the marine
environment by habitat and mobility
Plankton (floaters)
 Nekton (swimmers)
 Benthos (bottom dwellers)
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http://i.ehow.com/images/GlobalPhoto/Articles/2110315/icephytoplankton-main_Full.jpg
Plankton
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Most biomass on Earth consists of plankton
Phytoplankton
 Microscopic algae, Autotrophic
Zooplankton
 Heterotrophic
 Protozoans, tiny animals, larvae of larger
animals
Bacterioplankton
Virioplankton

Viruses that infect bacteria and eukaryotic cells
Plankton
o
Holoplankton
o
o
o
Meroplankton
o
o
o
o
Part of lives as plankton
Juvenile or larval stages in the plankton
Examples are lobsters, some fish species, etc.
Macroplankton
o
o
Entire lives as plankton
Example is algae, protozoans, small microscopic
animals
Large floaters such as jellyfish or Sargassum
Picoplankton
o
Very small floaters such as bacterioplankton
Nekton
Independent
swimmers
 Most adult fish
and squid
 Marine reptiles
 Marine mammals
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Benthos
Epifauna live on surface
of sea floor
 Infauna live buried in
sediments
 Nektobenthos swim or
crawl through water
above seafloor
 Most abundant in
shallower water
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Number of marine species
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More land species than marine species
 Ocean relatively uniform conditions
 Therefore, less adaptation required, less speciation
 Don’t get this fact confused with # of individual organisms
 There are fewer different species in the ocean but greater # of individuals
 Majority of life on Earth lives in the ocean!!
 Diversity in the ocean is high, also – think about different types of fish
(seahorses to sharks, for example)

Marine species overwhelmingly benthic rather than
pelagic
○ Most of these will be in shallow coastal benthic areas where
there is light and a lot of primary productivity
Marine organisms have a lot of
adaptations for living in the marine
environment
 Let’s take a look at some of these
adaptations
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Adaptations of marine organisms
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Physical support
 Buoyancy
 How to resist sinking
 Different support structures in cold (fewer)
rather than warm (more appendages)
seawater
 Smaller size
http://www.solaster-mb.org/mb/images
Adaptations to marine life

Oil in micro-organisms to
increase buoyancy
○ Over-time, if these
organisms die and sink to
bottom
○ Can become offshore oil
deposits
Fish egg with oil droplet
Fig. 12.9
http://www.rpgroup.caltech.edu/~natsirt/aph162/webpages/dylanandco/lab1/image
Adaptations to marine life
Streamlining important for
larger organisms
 Less resistance to fluid flow
 Flattened body
 Tapering back end –
fusiform
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http://www.wissenschaft-online.de/sixcms/media.php/591
Fin designs in fish
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Vertical fins as stabilizers
○ dosral and anal fins
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Paired fins for “steering” and balance
○ Pelvic and pectoral
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Tail fin (caudal) for thrust
http://www.biologycorner.com/resources/fish_fins.gif
Adaptations to marine life
Narrow range temperature in oceans
 Smaller variations (daily, seasonally, annually)
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 Remember it takes longer to change water temp
than air temp
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Deep ocean nearly isothermal
Adaptations to marine life
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Cold- versus warm-water species
 Smaller in cooler seawater
 More appendages in warmer seawater
 Why?
 Tropical organisms grow faster, live shorter,
reproduce more often
 Higher # of species in warmer seawater
 Not necessarily higher # of individuals
 More biomass in cooler seawater (upwelling)
 Polar waters are much more productive
(more plankton growth) than tropical
waters
Adaptations to finding prey
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Most fish coldblooded but some
are warm-blooded
 Homeothermicbody temperature
above sea water
temperature
 Modifications in
circulatory
system
 Mainly in fastswimming fish
http://www.sciencedaily.com/images/2005/10/051031133653.jpg
Adaptations of deep-water nekton
Mainly fish that consume detritus or each
other
 Lack of abundant food
 Bioluminescence
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○ http://www.ted.com/talks/edith_widder_glowing_life
_in_an_underwater_world.html
Fishing lures
 Large,
sensitive eyes
Anglerfish
w/ males

http://www.antoranz.net/CURIOSA/ZBIOR2/C0301
Lanternfish
http://www.lifesci.ucsb.edu/~biolum/organism/pictures/myctophid1.jpg
Adaptations to marine life
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Stenothermal
 Organisms withstand small variation in
temperature
 Typically live in open ocean

Eurythermal
 Organisms withstand large variation in
temperature
 Typically live in coastal waters
Adaptations to marine life
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Stenohaline
 Organisms withstand only small variation in
salinity
 Typically live in open ocean
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Euryhaline
 Organisms withstand large variation in salinity
 Typically live in coastal waters, e.g., estuaries
Adaptations to marine life
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Extracting minerals from seawater
High concentration to low concentration
 Diffusion
 Cell membrane permeable to nutrients, for
example
 Waste passes from cell to ocean
Adaptations to marine life
Osmotic pressure
 Less concentrated
to more
concentrated
solutions
 Isotonic
 Hypertonic
 Hypotonic
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Adaptations to marine life
Dissolved gases
 Some animals extract dissolved oxygen (O2)
from seawater through gills
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Fig. 12.15
Adaptations to marine life
Water’s transparency
 Many marine organisms see well
 Some marine organisms are nearly
transparent to avoid predation
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Adaptations to marine life
Camouflage through color patterns
 Countershading
 Disruptive coloring
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http://www.youtube.com/watch?v=PmDTtkZl
MwM
http://theplasticocean.blogspot.com/2012_07_01_archive.html
Adaptations to marine life
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Water pressure
 Increases about 1 atmosphere (1 kg/cm2) with
every 10 m (33 ft) deeper
 Many marine organisms do not have inner air
pockets
 Collapsible rib cage (e.g., sperm whale)
Main divisions of the marine environment
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Pelagic (open sea)
 Neritic (< 200 m) and oceanic
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Benthic (sea floor)
 Subneritic and suboceanic
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Another classification scheme:
 Euphotic
 Disphotic
 Aphotic
Pelagic environments – Open ocean
Epipelagic
 Mesopelagic
 Bathypelagic
 Abyssopelagic
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Fig. 12.19
Benthic environments – ocean floor
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Supralittoral
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Transition from land to seafloor
Subneritic (under neritic)
 Littoral
(intertidal zone)
 Sublittoral
(shallow tidal
zone to 200m)

Suboceanic
 Bathyal
(200-4,000m)
 Abyssal
(4000-6000m)
 Hadal
(below 6000m)
Fig. 12.19
Distribution of benthic organisms
Fig. 15.1
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More benthic productivity when closely beneath areas of
high surface primary productivity
 Mainly on continental shelves
 Affected by surface ocean currents
Humans and coral reefs
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Activities such as fishing,
tourist collecting, sediment
influx due to shore
development harm coral reefs
Sewage discharge and
agricultural fertilizers increase
nutrients in reef waters
 corals thrive at low nutrient levels
 Phytoplankton overwhelm at high
Coral covered with macroalgae
nutrient levels, limit light reaching
the corals
 Bioerosion of coral reef by algaeeating organisms
http://daac.gsfc.nasa.gov/oceancolor/images/coral_reef_algae.jpg
Ocean Literacy Principles
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3.e - The ocean dominates the Earth’s carbon cycle. Half the primary productivity on Earth
takes place in the sunlit layers of the ocean and the ocean absorbs roughly half of all
carbon dioxide added to the atmosphere.
5.a - Ocean life ranges in size from the smallest virus to the largest animal that has lived
on Earth, the blue whale.
5.b - Most life in the ocean exists as microbes. Microbes are the most important primary
producers in the ocean. Not only are they the most abundant life form in the ocean, they
have extremely fast growth rates and life cycles.
5c. - Some major groups are found exclusively in the ocean. The diversity of major groups
of organisms is much greater in the ocean than on land.
5.e - The ocean is three-dimensional, offering vast living space and diverse habitats from
the surface through the water column to the seafloor. Most of the living space on Earth is
in the ocean.
5.f - Ocean habitats are defined by environmental factors. Due to interactions of abiotic
factors such as salinity, temperature, oxygen, pH, light, nutrients, pressure, substrate and
circulation, ocean life is not evenly distributed temporally or spatially, i.e., it is “patchy”.
Some regions of the ocean support more diverse and abundant life than anywhere on
Earth, while much of the ocean is considered a desert.
5.g - There are deep ocean ecosystems that are independent of energy from sunlight and
photosynthetic organisms. Hydrothermal vents, submarine hot springs, methane cold
seeps, and whale falls rely only on chemical energy and chemosynthetic organisms to
support life.
Sunshine State Standards
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SC.6.L.14.3 - Recognize and explore how cells of all organisms undergo similar
processes to maintain homeostasis, including extracting energy from food, getting
rid of waste, and reproducing.
SC.7.L.17.3 - Describe and investigate various limiting factors in the local
ecosystem and their impact on native populations, including food, shelter, water,
space, disease, parasitism, predation, and nesting sites.
SC.912.L.15.5 - Explain the reasons for changes in how organisms are classified.
SC.912.L.15.6 - Discuss distinguishing characteristics of the domains and
kingdoms of living organisms.
SC.912.L.17.2 - Explain the general distribution of life in aquatic systems as a
function of chemistry, geography, light, depth, salinity, and temperature.
SC.912.L.17.7 - Characterize the biotic and abiotic components that define
freshwater systems, marine systems and terrestrial systems.