Lecture on Sharks and Buoyancy - MPA Monday

Introduction

• Speaker: Angie, Interpreter for California State Parks.
• Event: MPA (Marine Protected Areas) Monday.
• Topic: Discussion on Sharks and their buoyancy.
• Context: Building on Shark Week discussions.

Key Topics

Elasmobranchs

• Definition: A subclass of the class Chondrichthyes.
• Examples: Sharks, Skates, and Rays.
• Characteristic: Cartilaginous fishes.

Fish Buoyancy

• General Fish Buoyancy: Most fish have a swim bladder similar to human lungs for buoyancy.
• Pressure & Boyle's Law: As fish ascend, pressure decreases and the swim bladder expands.

Elasmobranch Buoyancy

• Absence of Swim Bladder: Sharks do not have swim bladders to maintain buoyancy.
• Adaptation: Use of a large oily liver instead.
  • Oil Density: Oil has a lower density than water assisting in buoyancy.
  • Oily Liver Characteristics:
    • Takes up 90% of body cavity.
    • Accounts for 25% of body weight.
    • Contains squalene, a compound that can provide nutrients during food scarcity.

Experiment Demonstrating Buoyancy

• Setup: Two toilet paper roll sharks, one with a bag of oil and one without.
• Hypothesis: Shark with oily liver will float.
• Observation: The shark with the oily liver floated; the one without sank.

Additional Information

• Sharks' Need to Swim: Sharks must constantly swim for respiratory needs.
• Marine Protected Areas (MPAs)
  • California has 124 MPAs.
  • Benefits marine life diversity, including some sharks.
  • Indirect benefits for migratory sharks.
  • Poster available for MPAs and their benefits.

Conclusion

• Ongoing Programs: Daily virtual programs related to North Coast State Parks.
• Engagement Encouragement: Viewers invited to ask questions and engage.
• Upcoming Topics: More on sharks and marine animals in future sessions.

Note: Virtual programs continue amid COVID-19 to keep communities connected to state parks.