Ultrasonic sensor working underwater?

[Tushara Gudimetla]

Does ultrasonic sensor works in water?Does it cause any harm to fish and shrimps?
How we should detect the shape of the object using sonar sensor?

 

[Alec_t]

Welcome to EP!
Some ultrasonic sensors are designed to work in liquid, others aren't.
High enough sound/ultrasound levels can stun or harm animals.
Shape detection would depend on the size of the object relative to the transducer dimensions and operating frequency. Sonar, with a directional beam, is commonly used to map sea-bed shape and to image wrecks.