Exam Study Notes - Ocean Zones, Plate Tectonics, and Marine Life

Ocean Zones and Plate Tectonics

Bathymetry

• Study of seafloor and other water body floors (rivers, lakes, etc.).

Photic vs. Aphotic Zones

• Photic Zone:

  • Top layer with sunlight.

  • Surface.

• Aphotic Zone:

  • No sunlight; less than 1% light penetration.

Pelagic vs. Benthic

• Pelagic:

  • Open water organisms.

• Benthic:

  • Bottom-dwelling organisms.

Ocean Zones

• Epipelagic Zone:

  • Light = life.

• Mesopelagic Zone:

  • Some light, but not enough for photosynthesis.

Key Questions and Answers about Ocean Zones:

• Which zone has the most life? Why?

  • Epipelagic zone because sunlight is most accessible.

• Which zone has enough light for photosynthesis?

  • Euphotic zone (part of the epipelagic).

• Which zones are in total darkness all the time?

  • Aphotic zone (includes bathypelagic and abyssopelagic zones).

• What is the deepest zone?

  • Hadalpelagic zone.

• Most of the ocean is in which zone?

  • Bathypelagic zone.

• Which zone has the most biomass (life)? Why?

  • Neritic zone because it’s most productive with sunlight, high oxygen levels, and stable temperatures.

• Which zones have no light?

  • Aphotic zone (bathypelagic, abyssopelagic, and hadalpelagic zones).

• At what depth is all light gone?

  • Below 1,000 meters.

• Which zone has the greatest temperature changes?

  • Mesopelagic Zone due to the thermocline.

Stressors of Living in the Deep Sea:

• Light availability.

• Extreme pressure.

• Extreme temperatures (around 39°F or 4°C) that persist with no seasonal fluctuations.

• Scarcity of food.

• Difficulty finding mates.

• Oxygen availability.

• Predation.

Deep-Sea Adaptations:

• Anatomical Adaptations:

  • Pigmentation: Transparent, black, or red (red light is filtered out in deep waters).

  • Large eyes.

  • Frail/flabby body shape.

  • Slender/elongated body shape.

  • Large mouth.

  • Weak jaws.

  • Large gill slit area.

• Physiological Adaptations:

  • Slow metabolism to conserve energy.

  • Gene mutation for antifreeze production.

  • Bioluminescence to attract prey, confuse predators, or for counterillumination.

  • Low metabolism to adapt to less food.

  • Reproduction using light patterns/bioluminescence to attract mates.

  • Long life (achieved through gene mutation).

• Behavioral Adaptations:

  • Bioluminescence for various purposes.

Deep Sea Feeding

• Feed on decay/rotting things, dead organic matter from waters above (carrion, excrement, shells).

Examples of Deep-Sea Creatures and Their Adaptations:

• Vampire Squid: Red pigmentation, glowing eyes.

• Frilled Shark: Long, thin body.

• Pelican Eel: Large mouth.

• Flashlight Fish: Bioluminescent line under eyes for communication, evading predators, attracting prey, and attracting potential mates.

• Siphonophores: Bioluminescence to attract prey, which they then sting with long tentacles.

• Invertebrates: Examples include amphipods (some species up to 13 inches) and giant isopods (up to 2.5 ft).

• Ice Dragon Fish: Produce antifreeze proteins in blood (adaptation to Antarctica).

• Firefly Squid: Example of bioluminescence.

• Polychaete Worms

• Zooplankton

Additional Adaptations

• Migratory behavior (diel vertical migration): Synchronized migrations.

• Use of mucus to create nets to catch materials.

Gene Mutation

• Chemical reactions within cells.

Biotic factors

• Presence of others (predators)

• E.g. slowest metabolism of any cephalopod

• More gills

Plate Tectonics and Continental Drift

Location

• Latitude (x):

  • Horizontal lines.

  • Equator.

• Longitude (y):

  • Vertical lines.

  • Prime Meridian.

Parts of the Earth

• Crust.

• Mantle.

• Core.

Layers of the Earth

• Solid Inner Core (made of iron).

• Outer Core.

• Mantle.

• Crust.

  • Atop the lithosphere (where plates move).

    • Continental crust: Granite, less dense, older.

    • Oceanic crust: Basalt, more dense, younger.

Magma vs. Lava

• Magma: Molten rock underground.

• Lava: Molten rock above ground.

Theory of Plate Tectonics

• Earth’s crust is separated into many different sections called tectonic plates.

• Plate Boundary: An area where two tectonic plates meet.

Relationships Among Key Terms

• Pangaea: Supercontinent before plate movement caused continents to separate.

• Lithosphere: Includes crust and uppermost part of the mantle; divided into plates that glide over the asthenosphere.

• Asthenosphere: The plastic-like upper portion of the mantle. The lithosphere glides over it.

• Continental crust: Granite, less dense, older.

• Oceanic crust: Basalt, more dense, younger.

Evidence Supporting Plate Tectonics

1. Earth's magnetic field has reversed its polarity many times over geological history (magnetic north and south poles switched places).

2. When new oceanic crust forms at mid-ocean ridges through volcanic activity, it records the prevailing magnetic polarity at the time of its formation.

3. Creates stripes of alternating magnetic polarity along the ocean floor (crust with positive and negative anomalies).

Plate Boundaries/Zones and Their Effects

• Continental drift: Caused by convection currents (circulate air), which is the movement of fluid + magnetic fields in the atmosphere. This causes plates to move.

  • Magnetic fields created by moving electric charges (around each atom; electrons).

• Subduction:

  • Tectonic plates at convergent boundaries, one plate driven beneath the other (Earth's interior).

  • Features: Trench, earthquakes, volcanoes.

• Convergent:

  • Tectonic plates come together.

  • Features: Mountains, trench, earthquakes, volcanoes.

• Divergent:

  • Tectonic plates move away from one another.

  • Magma rises from the mantle, fills gaps, and hardens into solid rock.

  • Features: Mid-ocean ridges, rift valleys, hydrothermal vents, volcanoes.

• Transform:

  • Tectonic plates slide past each other.

  • Causes friction, creating earthquakes.

Deepest Part of the Ocean

• Created by subduction (e.g., Mariana Trench in the Pacific).

Tectonic Plates

• North American

• South American

• Eurasian

• Antarctic

• Pacific

• Australian

• Indian

• African

• Cocos

• Nazca

• Juan de Fuca

• Arabian

• Caribbean

• Philippine

• Scotia

Hot Spots

• Areas where volcanic islands form due to magma piling up from Earth’s interior, hardening, and eventually breaking the water surface (e.g., Hawaiian Islands).

Ring of Fire

• Tectonic belt around the Pacific Ocean with high activity of volcanoes and earthquakes.

• Caused by subduction (convergent plate boundaries).

• The abundance of volcanoes and earthquakes is due to the significant movement of plates in the area.

Mid-Ocean Ridge

• Divergent plate boundary.

• Underwater mountain range (e.g., Mid-Atlantic Ridge).

• Prevalent hydrothermal vents due to magma (heat source).

• Age of rocks at ridges:

  • Seafloor deposits new layers and pushes older deposits away from the mid-ocean ridge.

  • Rocks at the origin are younger.

Atoll Formation

1. Underwater volcano pierces the surface of the ocean.

2. Coral reef forms around the volcanic island.

3. Reefs surround sinking island.

4. A barrier reef protects the lagoon.

Sea Floor Features

• Continental shelf

• Continental slope

• Continental rise

• Abyssal plain

• Seamount

• Mid-Atlantic ridge

• Island

• Trench

Tsunamis

• Giant waves caused by earthquakes or volcanic eruptions underwater.

• Rapidly flood land with strong currents.

• The force of water + debris causes destruction and injuries.

Tsunami Speed Formula

• $Speed = {g \times d}$

• Where:

  • Speed is the speed of the tsunami in meters/second.

  • $g$ is the acceleration due to gravity ($9.81$ meters/second$^2$).

  • $d$ is the water depth in meters.

Hydrothermal Vents

• Opening/crack on the seafloor where hot, mineral-rich water is discharged.

• Formed at divergent boundaries, allowing magma to reach the surface (e.g., East Pacific Rise, Mid-Atlantic Ridge).

Vent Water Properties:

• Warm due to hot magma.

  • Temperature range: 60°C - 450°C.

• Extremely acidic (pH around 3.0, similar to vinegar).

Vent Organisms:

• Giant tube worms.

• Zoarcid fish (top predators around vents).

• Giant clams.

• Galatheid crab.

• Squat lobster.

Symbiotic Relationships at Hydrothermal Vents

• Tube Worms and Bacteria:

  • Tube worm cavity is packed with bacteria that manufacture sugars the worm uses as food (symbiotic relationship).

  • Benefit for bacteria: protection, oxygen and hydrogen sulfide supply.

  • Benefit for tube worm: relies on bacteria for nutrition.

• Bacteria Role:

  • Cavity: Packed with bacteria → manufacture sugars (chemosynthesis).

  • Worm absorbs some of the sugars, usage: food

  • Worm tube: Made of chitin. Protection from predators and toxins of vents. Supports worm (outer skeleton)

  • Holds the worm in the tube

  • Plume: Filters oxygen, hydrogen sulfide, and carbon dioxide → transports to bacteria in cavity

Chemosynthesis vs. Photosynthesis

• Vents are rich in dissolved minerals, supporting large populations of chemoautotrophic bacteria.
  Bacteria produce energy without light.
  Organisms use sunlight to synthesize foods; involving chlorophyll
  Plants use sunlight, water, and carbon dioxide → create oxygen and energy (form of sugar)
  Used by photosynthetic organisms
  Produce Energy- Rich Sugar Bacteria are primary producers
  Used by bacteria

Marine Snow

• Organic material (mostly detritus): fecal matter, remains, shells of planktonic organisms.

Hydrothermal Vent Food Chain

• Producer: Bacteria (symbiotic relationship with vent animals like tubeworms, clams, mussels).

• Primary Consumer: Zooplankton, shrimp, amphipods, small crustaceans, limpet, polychaete, tubeworm, shrimp, snail, zooplankton, clam, mussel.

• Secondary Consumer: Small crabs, fish, siphonophore, anemone, scallop, barnacle.

• Tertiary Consumer: Lobster, larger crabs (some are detritivores: feed on dead animals and remains), octopus, fishes.

Seafloor Mapping

• Sonar is used to map the seafloor.

  • Acoustic signals (sound) bounce off the seafloor and return an echo. The strength of the signal indicates depth and seafloor features.

Underwater Exploration Tools

• AUV (Autonomous Underwater Vehicle):

  • Advantages: Can explore very deep areas.

  • Disadvantages: Cannot be controlled by humans.

• ROV (Remotely Operated Vehicle):

  • Advantages: -

  • Disadvantages: Small and May get stuck.

• HOV (Human Occupied Vehicle):

  • Advantages: Human-controlled.

  • Disadvantages: Risks to humans.

• SCUBA*:

  • Disadvantages: Not very deep

Fish Taxonomy and Anatomy

Fish Taxonomy

• Domain: Eukaryota

• Kingdom: Animalia

• Phylum: Chordata

• Class: Pisces

Subclasses of Fish

• Agnatha: Jawless

  • Examples: Hagfish, Lamprey

• Chondrichthyes: Cartilaginous

  • Examples: Sharks, Rays, Skates, Sawfish

• Osteichthyes: Bony

  • Examples: Salmon, Trout

Fish vs. Fishes

• Both are plural, but "fishes" is used scientifically for more than one species.

Fish Anatomy and Function

• Function of the following structures:

  • Eyesight: vision

  • Nostrils / nares: smell

  • Swim bladder: gas-filled bladder, aids buoyancy

  • Ampullae of Lorenzini: electroreceptors (network of mucus-filled pores) aka sensory organs that detect electric fields

  • Lateral line: at perforated scales, series of sense organs that detect pressure and vibration

  • 2 chambered heart: single atrium and a single ventricle connected by a common atrioventricular valve

  • Mucus / scales: mucus is secreted from the cells located at the outer skin (epidermis) covering the fish scales, reduces drag, less friction

  • Liver and oils: buoyancy

  • Chromatophores: pigment-bearing cells shift body coloration and pattern; provides camouflage and communication

  • Pectoral: steering, brakes

    • Pelvic: balance, prevent rolling

    • Anal: stabilize (keel of boat)

    • Anterior dorsal: stabilize

    • Posterior dorsal: stabilize

      • Caudal: thrust

Fish Morphology

Caudal Fin Shape and Function

• Blue Marlin, Mummichog, Briad Flounder, Green Moray Eel

• Which of these fish swims the fastest in open water?
  Blue Marlin

• Which fish can make sharp turns?
  Mummichog

• Which fish can not make sharp turns?
  Blue Marlin

• Which fish is a great sprinter but not fit for a long distance marathon
  Broad Flounder

• Which fish swims like a flying bird?
  Broad Flounder

• Which fish slithers through the water like a snake?
  Green Moray Eel

• Which fish lives on the seafloor?
  Broad Flounder

General Fish Adaptations

1. Streamlined body to reduce drag.

2. Gills for respiration.

3. Scales / mucus for waterproof and to reduce drag.

4. Swim bladder for buoyancy.

Species-Specific Adaptations

• Warning coloration: Coloration to communicate danger to predators.

• Countershading: Using dark color patterns on top, and white on the bottom.

• Disruptive coloration: Color patterns break up the outlines of an animal, hiding vulnerable areas.

• False eyespot: Coloration that looks like eyes to confuse predators.

• Schooling: Travel in large numbers to confuse predators.
  Schooling. Lateral lines help sense location to one another by detecting vibrations

1. Protection from predation

2. Patterns (travel distances)

3. Mating: increases reproductive success
   Lateral lines help sense location to one another by detecting vibrations

Respiration

• Operculum: Gill cover.

• Gill rakers: Bony spines that prevent solid particles from entering the gills.

• Gill arch: Bony loops which support the gills.

• Gill filaments: Hold gills in place, water flows in a direction alongside them while blood flows in the opposite direction.

• Gill slits: Water passes from the pharynx to exterior, bathing gills in the process.

• ** Spiracles**: Openings behind fish eyes that pull in oxygenated water

• Counter-current flow: Mechanism in which oxygen enters the blood in fish (blood flows in opposite direction to water flowing over gills).

Fish Reproduction

• Spawning: the act of releasing eggs and sperm

• Claspers: Reproductive organs of male chondrichthyans. Inserted in female for internal fertilization. “Clasps” the walls of the female oviduct.

• Types of Birth:

  • External reproduction: Female releases lots of unfertilised eggs in the water.

  • Oviparous: Lay eggs.

  • Ovoviviparous: Eggs hatch inside the mother.

  • Viviparous: Live birth.

Anadromous vs. Catadromous

anadromous: Live in saltwater, migrate to freshwater to spawn
salmon and trout
Catadromous: Live in freshwater and migrate to saltwater to spawn
American Eel

Fish Ladder

• Allows passage over dams or other obstacles for migrating fish.

• Ascending pools.
  Salmon Developmental Index: influence development rate using temperature.

Sharks vs. Bony Fishes

• Sharks float without a swim bladder due to their oil-filled liver.

• Due to pectoral fins not being flexible and lack of brakes, sharks can’t move backwards.

• There are thousands of bony fish species but only ~500 shark species because sharks take longer to reach sexual maturity.
  Sharks vs Rays
  Ram ventilation vs Spiracles

Seahorses / Sea Dragons

• Seahorses: Male impregnation: incubate embryos in pouch.

• Sea dragons: Male brood patch, fertilization (stick to under surface of tail).

Sustainable Fishing Key Terms

• Stock Size: biomass of fish, amount remaining in water.

• Sustainable Fishing: little damage to ecosystem.

• Unsustainable Fishing: severe damage to ecosystem, detrimental to fish populations.

• Overfishing: excessively fishing a population to the point it’s unstable.

• Fishing Mortality: intensity of fish stock exploitation.

• Bycatch: non-target species accidentally caught by fishermen.

• Quota: limited amount product can be produced / exported / imported.

• Maximum Sustainable Yield: max amount resource can be exploited without long-term depletion (largest catch that can be taken from a fish stock without affecting future year population rates).
  Sustainable Yield Curve
  Tonnage of Fish Yield per Annum
  fishing Effort
  Salmon Life Cycle
  Developmental Index
  Critical Zone
  Exhaustion

Sustainable fishing

Population dont get depleted by guaranteeing reproduction
ecosystems available for generations
health risk reduces or eliminated
tastes better

Commercial Fishing Methods

Marine Fishing Regulations

Why should a consumer care about the sustainability of seafood?
Populations not depleted by guaranteeing reproduction
Ecosystems available for future generations
Health risks (overfished or not sustainably farmed seafood has higher amounts of Mercury, PCBs, contaminants)
Low populations will drive up prices
Employment rates decrease
What regulations are in place to protect fish in Connecticut state waters?
Size, ,Season, and Possession limits
How do these regulations lead to sustainability?
Ensures young / juvenile survive → ability to reproduce
Ensures fishermen don’t overfish in nursery grounds
Ensures fishing mortality is stable to support future populations

Marine Mammals Taxonomy and Characteristics

Taxonomy

• Domain: Eukarya

• Kingdom: Animalia

• Phylum: Chordata

• Subphylum: Vertebrata

• Class: Mammalia

  • Order:

    1. Pinnipedia: seals, sea lions, walruses

    2. Cetacea: toothed / baleen whales

    3. Sirenia: manatees, dugongs

Cetacean Suborders

• Mysticeti (baleen): made of keratin

• Odontoceti (toothed)

Key Vocabulary

• Melon: Adipose tissue in the forehead of all toothed whales. Focuses and modulates vocalizations; sound lens.

• Echolocation: Remarkable sensory ability used for locating food and for navigation underwater, utilizing sound.

Mammalian Characteristics

• Warm-blooded:
  * Mechanisms to maintain a constant internal body temperature: Countercurrent heat exchange, high metabolism, insulation (blubber, fur, hair), behavioral strategies (surfacing for warmth).

• Live birth

• Hair / fur

• Mammary glands

• Blubber

Cetacean Characteristics

• No hind limbs

• Muscular tail

• Fish-like body form

• Blowhole at the top of the head for breathing

• Blubber (fat layers) to insulate the body

• Social creatures that travel in groups called “pods”

• Noises to communicate / socialize

  • Clicks.

  • Whistles.

  • Pulsed calls.

Baleen vs. Toothed Whales

Seals vs. Sea Lions

Dolphins vs. Porpoises

Human Impact on Cetaceans

• Whaling: directly killing

• Ship strikes: collisions with whales, thereby killing or injuring

• Entanglement: bycatch, indirectly killing

• Pollution: affecting habitat and prey movements / migrations

Stranding

• injuries caused by ship / vessel collisions

• Noise pollution

• entrapment or entanglement in fishing gear
  Most stranded marine mammals are endangered

seahorses/sea dragons

Their reproductive behaviour is that make impregnate embryos in pouch/under surface of tail respectively. Marine mammals strand due to ship injuries noise pollutions and fishing line trap. Marine mammals are endangered species. Because of this they are strand themselves.