B3.3.1 Adaptations for movement as a universal feature of living organisms Notes

There Are Two Types of Movement in Living Organisms

1. Internal Movement occurs within the body of all living organisms, even stationary ones.
2. It is essential for nutrient distribution, waste removal, and maintaining cellular functions.
3. Locomotion on the other hand, involves moving from one location to another.
4. It enables organisms to find resources, evade predators, and adapt to changing environments.

Motile vs. Sessile Organisms: A Comparison

Motile Organisms

1. Actively move through their environment to find food, escape predators, or reproduce.
2. Adaptations:
   1. Skeletal and Muscular Systems: E.g., elongated limbs in cheetahs for speed.
   2. Energy Storage: Migratory birds store fat reserves before long flights.
   3. Behavioral Strategies: Moving in response to seasonal cues or predator threats.

Sessile Organisms

1. Remain fixed in one location for most of their lives (e.g., barnacles, corals).
2. Still exhibit movement at smaller scales:
   1. Feeding: Barnacles use cirri (modified legs) to filter water. Corals use tentacles to capture food.
   2. Larval Motility: Many sessile species have motile larval stages for dispersal.
   3. Anchorage Mechanisms: Strong attachments (e.g., adhesive cement in barnacles, calcium carbonate skeletons in corals) to remain in place.

Adaptations for Movement Across Taxonomic Groups

1. Movement in Unicellular Organisms
   1. Flagella and Cilia: Whip-like or hair-like structures powered by motor proteins.
   2. Cytoplasmic Streaming: In Amoeba, cytoplasm flows to form pseudopodia, aiding movement and feeding.
2. Movement in Vertebrates
   1. Skeletal Systems: Endoskeletons provide support and anchor muscles.
   2. Muscular Systems: Skeletal muscles contract via the sliding filament model (interaction of actin and myosin).
   3. Joint Structures: Synovial joints (e.g., ball-and-socket) allow a wide range of motion.
3. Movement in Marine Mammals
   1. Streamlined Bodies: Reduce drag when swimming.
   2. Modified Limbs: Flippers and flukes for propulsion and maneuvering.
   3. Blubber: Provides buoyancy and insulation in cold water.

Why Movement Matters

1. Foraging: Searching for or capturing food (predators chasing prey; herbivores seeking plants).
2. Escaping Predators: Rapid locomotion reduces the risk of being caught.
3. Reproduction: Movement facilitates finding mates or dispersing offspring.
4. Migration: Seasonal journeys (e.g., snow geese) ensure access to food and breeding sites.