1. Challenges of the Marine Environment
- Evolution via Natural Selection
- Physical Factors in the Marine Environment – Light and Floatation
Reading – 4th Ed:
Ch 13 Secs 2, 5, 12-13, 15, 17-18, 29
Ch 6 Secs 18-20
Ch 15 Secs 21, 24
Reading – 5th Ed:
Ch 13 Secs 2, 13-14, 25-26, 28
Ch 6 Secs 21-23
Ch 15 Secs 22, 25
Graphic: Tuna. Courtesy of United Nations Food and Agricultural Organization.
2. Life in the Ocean
Living things:
- Contain matter in an organized state
- Can capture, store and transmit energy
- Can reproduce and change through time
- Can adapt to their environment
Graphic: Christmas tree worms, spirobranchus giganteus, on Elbow Reef.
Photograph by J.Guttuso, courtesy National Marine Sanctuaries Collection.
3. Evolution and Natural Selection
Evolution = the maintenance of life under constantly changing conditions by
continuous adaptation of successive generations of a species
Natural selection is the process by which life evolves
Graphic: Whale evolution, courtesy of Arizona State University.
4. What is a Species?
Species = a group of potentially interbreeding organisms that is reproductively
isolated from all other living things
Graphic: (top) Elephant seals, Weddell seals, J.Roletto, photographer, NMS
collection. (bottom) Weddell seals, Cmmdr. J.Bortniak, photographer, NOAA Corps
collection.
5. Theory of Evolution by Natural Selection
1. More offspring are produced than can survive
2. Random genetic variations occur in offspring, some of these increase
chances for survival
3. Carriers of favorable traits are more successful and have more
offspring - favorable traits accumulate in the population
4. Isolation of sub-populations can lead to new species as
sub-populations become genetically distinct
Graphic: Garrison, 4th Ed., Fig. 13.6, pg 326, 5th Ed., Fig. 13.19, pg 322.
6. Natural Selection and the Environment
A species' response to its environment is central to its survival
Chemical environment: nutrients, pH
Physical environment: temperature, light
Biological interactions: predation, competition
Graphic: Loggerhead turtle babies, courtesy of NOAA.
7. Evolution and Natural Selection in Action
Adaptive mutations: e.g., drug-resistant bacteria
Co-evolution: Simultaneous reciprocal evolution of species e.g., clams/drilling
snails
Convergent evolution: Evolution of similar characteristics in species of
different ancestry, e.g., front appendages of various marine organisms
Graphics: (top) Salmonella typhimurium (red) invading cultured human cells,
Rocky Mountain Laboratory, NIAID, NIH, (bottom) Garrison, Fig. 13.7, pg 330.
8. Physical Factors in the Marine Environment
Physical factor = Any aspect of the physical environment that affects living
organisms
Examples:
- Light*
- Acid-base balance
- Temperature
- Hydrostatic pressure
- Salinity
- Negative buoyancy (floatation)*
- Dissolved nutrients - Viscosity (ease of movement)*
- Dissolved gases
Each physical factor presents unique challenges to a species
9. Some Typical Marine Plants and Animals
Most marine plants and animals are small due to the challenges of light
availability and floatation
Graphics: (top left) Chaetoceros concavicornis, courtesy of NOAA, (top right)
krill, courtesy of National Marine Fisheries Service, (bottom left) copepod,
courtesy of NOAA.
10. Zones of Light Penetration
Euphotic zone: Enough light for photosynthesis and vision (0-70 m)
Disphotic zone: Enough light for vision only (70-600 m)
Aphotic zone: Insufficient light for photosynthesis and vision (below ~600 m)
Graphic: Garrison, 4th Ed., Fig. 14.14, pg 362, 5th Ed., Fig. 13.12, pg 316.
11. Marine Plants - Limited by Light Availability
Marine plants:
- Require sunlight to grow
- Are restricted to areas near the ocean's surface
Light availability limits marine plant growth
Because plants are the base of most marine food chains, most sea life lives near
the ocean's surface
Graphic: Left: Marine phytoplankton (plants). Images courtesy of NASA/Goddard
Space Flight Center.
12. Adaptations to Light Availability - Marine Animals
Upper ocean - "normal" eyes
Lower disphotic - large eyes
Deep aphotic - small, non-functioning or no eyes
Graphics: Courtesy of National Marine Fisheries Service, Historic Collection
13. Making Your Own Light - Bioluminescence
Bioluminescence = production of light by living creatures
At mid- to deep depths, bioluminescence can be used to:
- Lure prey
- Avoid predators
Graphic: Black dragon fish (female). Bauer 1906.
14. Alternatives to Vision: Echolocation
Sound is easily transmitted through seawater
Echolocation:
Using sound to determine the location of objects
Usually used to find prey and avoid obstacles
Graphic: Garrison, Fig. 15.40, 4th Ed., pg 406, 5th Ed., pg 384.
15. Alternatives to Vision: Electricity and the Sea
Some marine animal have receptors that can detect minute electrical currents
- Pores in a shark’s head contain a jelly that detects weak electrical fields
produced by muscle contractions
- Electroreceptors help marine animals navigate using the Earth's magnetic field
Graphic: Blue shark, courtesy of Channel Islands National Marine Sanctuary, and
NOAA.
16. Alternatives to Vision: Vibration and the Lateral Line
Lateral Line - A network of fluid-filled vessels along the sides of the body
under the scales or skin
Detects the intensity and location of vibrations
Helps animals locate prey or evade predators
Graphic: White perch, J.Gunderson, photographer, courtesy of Minnesota Sea
Grant.
17. Floatation - A Matter of Survival for Marine Plants
Marine plants must be near the surface to survive
Various adaptations:
- Small size
- Shapes less prone to sinking
- Air-filled sacs
- Oil or waxes in cells
- Spines and other body projections
- Replace heavy chemicals with lighter ones
Graphic: Kelp forest. Courtesy of Channel Islands (California) National Marine
Sanctuary.
18. Sink or Swim... Floatation and Marine Animals
Many marine animals are more dense than seawater
Adaptations:
- Swim bladders (bony fish)
- Oily flesh (salmon)
- Strong swimming abilities (mackerel, bonita, sharks)
- Fins and tails that provide lift when swimming (sharks)
- Storing air in feathers or fur (penguins, otters, fur seals)
Graphic: Thrasher shark. Courtesy of National Marine Fisheries Service Historic
Collection.
19. The Drifters... Floatation and Marine Animals
Smaller and less rigid marine animals rely on more passive means for floatation
Adaptations:
- Air filled sacs (Portugese man of war)
- Lack of skeletons (jellyfish)
- Spines and other body projections (copopods)
Graphic: Cyanae jellyfish. P.Auster, photographer. Courtesy of National Undersea
Research Program and Univ. of Conn.
20. Life in a Viscous Fluid
Viscosity = a fluid's internal resistance to flow
High viscosity = motion is difficult
Ease of movement is related to the shape and size of an object and the
properties of the fluid
Graphic: Garrison, 4th Ed., Fig. 13.18, pg 341, 5th Ed., Fig. 15.30a-c, pg 374.
21. Reducing Drag
Streamlining reduces drag due to viscosity, allowing the swimmer to use less
energy
Streamlined bodies are smooth, elongated and tapered from mid-section to tail
Other strategies:
- friction-reducing mucus or oil
- skin texture
Graphic: (top) Monk seal, Dr. J.P. McVey, NOAA Sea Grant, (bottom) Dolphins in
bow wake. Cmmdr. G. Tuell, NOAA Corps. Both courtesy of NOAA.
22. Building a Better Fish - Propulsion
Forward motion requires effort from body and fins
Eels - move entire bodies to move forward (less efficient)
Advanced fishes - move tails and fins (more efficient)
Graphic: Garrison, 4th Ed., Fig. 15.29, pg 396, 5th Ed., Fig. 15.31, pg 374.
23. Preview of Next Lecture
Phytoplankton and Seaweeds: Salad Bar of the Sea
Reading:
4th Ed., Ch 14 Secs 2-5, 7-8, 10-12, 15-16, 19-23
5th Ed., Ch 13 Secs 3-6, Ch 14 Secs 2, 4-6, 9, 11-12, 14-18
Graphic: A chain of diatoms (marine plants). Paul Hargraves, photographer,
graphic courtesy of National Ocean Service.