Lecture Notes: Dolphins and Echolocation

Introduction

• Dolphins are loved for their graceful movement and playful behavior.
• Unique ability to navigate and hunt in ocean depths using echolocation.
• Echolocation is shared by porpoises, bats, and whales.

What is Echolocation?

• Functions like sonar on a submarine.
• Useful in murky ocean waters where visibility is low.

How Echolocation Works

• Dolphins emit ultrasonic clicks via nasal passages.
• Sound waves are concentrated and amplified by an organ called the melon.
• Sound waves travel into the water, bounce off objects, and return as echoes.
• Echoes are received by the dolphin’s lower jaw and forehead.
• Signals are interpreted by the brain to "see" using sound.
• Allows dolphins to determine shape, size, speed, direction, and even internal structures of objects around them.

Human Perception by Dolphins

• Dolphins can differentiate humans by echolocating their muscle, bone, scar tissue, and artificial body parts.

Discovery and Evolution

• Jacques-Yves Cousteau was a pioneer in studying dolphin echolocation.
• Echolocation likely evolved for survival, aiding in navigation, hunting, and predator avoidance.

Sound Frequency in Dolphins

• Dolphins use low-frequency signals for communication.
• High-frequency signals (up to 130 kHz) are used for echolocation.
• Dolphins are sensitive to noise pollution, which can cause disorientation and hearing loss.

Conclusion

• Importance of maintaining quiet ocean environments to protect dolphin health and well-being.