Lecture:1
Q: Where did life first begin?
A: Life began in a marine environment.
Q: What percentage of phyla are entirely marine?
A: More than half of all phyla are entirely marine.
Q: Why have most invertebrates been less successful on land than arthropods?
A: Because water provides physical support, stability, and moisture that land environments lack.
Q: What are the five main benefits of living in a marine environment?
A: Gas exchange, reproduction, mobility, excretion, and thermal stability.
Q: How does reproduction occur in marine environments?
A: Through external fertilization where gametes and zygotes get nutrients from the environment.
Q: What adaptations are needed for reproduction on land?
A: Internal fertilization and protective provisioning for zygotes or eggs.
Q: Why is movement easier in water?
A: Water supports body weight, allowing sessile lifestyles and less energy use.
Q: What mobility adaptations are necessary for land animals?
A: Support structures like skeletons and increased musculature for movement.
Q: How do marine animals excrete waste?
A: They release ammonia directly into the water, where it diffuses away.
Q: How do terrestrial animals handle excretion differently?
A: They convert ammonia into urea or uric acid and use specialized organs to conserve water.
Q: Why is temperature regulation easier in water?
A: Water has high thermal stability, keeping body temperatures constant.
Q: What adaptations are needed for temperature control on land?
A: Behavioral regulation and endothermy (being “warm-blooded”).
Q: What are the five main challenges of marine life?
A: Pressure differences, light limitation, low oxygen, high viscosity, and pollutants.
Q: How do deep-sea animals handle pressure changes?
A: Through unique physiology and behaviors that keep them at stable depths.
Q: Why is light a challenge in the ocean?
A: Light only penetrates 20–50 meters, limiting photosynthesis.
Q: What adaptations help organisms survive in low light?
A: Chemosynthesis or symbiotic relationships with photosynthetic organisms.
Q: Why is oxygen a challenge in marine environments?
A: Water holds less oxygen than air.
Q: How do marine animals adapt to low oxygen?
A: They live near currents or generate water movement to increase oxygen flow.
Q: How do marine animals cope with the density of water?
A: They have streamlined bodies for efficient movement.
Q: Why are pollutants a problem for marine animals, especially larvae?
A: Pollutants can damage delicate tissues and disrupt development.
Q: What are the three main challenges of freshwater life?
A: Osmotic pressure, ephemeral habitats, and changing pH/temperature.
Q: How do freshwater animals adapt to osmotic pressure?
A: They regulate ions and prevent excess water from entering their bodies.
Q: What do animals do when freshwater habitats dry up?
A: Enter dormant stages or produce protective eggs.
Q: What are some pre-adaptations that allowed animals to move onto land?
A: Internal fertilization, protective coverings, and desiccation-resistant eggs.
Q: Where can you find a summary of aquatic vs. terrestrial adaptations?
A: In Table 1.1 of the textbook.