The Serpent remotely operated vehicle (ROV) from Seaview Systems is designed for exploring very small-diameter pipelines. It can investigate conduits as small as 9 inches (23 cm) in diameter, and fit around bends with a radius as narrow as 27 inches (68.5 cm). Measuring 9 inch x 9 inch x 57 inch (23 cm x 23 cm x 145 cm) and weighing 70 lb (32 kg), the Serpent runs on two 300W brushless DC motors that give it a total forward thrust of 18 lb (8 kg). With a 0.5 inch (1.3 cm) diameter fiber-optic tether, it can explore as far as 6,000 ft (1,830 m) down a pipe or tunnel. A 360-degree pan/orbit/zoom color camera and two color cameras are included, along with two 70W high-intensity LEDs. The robot also has heading, pitch and roll, and depth sensors, as well as sonar. A fiber-optic telemetry system provides up to three video channels, four RS232 channels, and two RS485 channels. (Source: Seaview Systems)
Nice slideshow Ann. Quite a wide range of differences in structure. It would be interesting to know whether the robots designed to look like sea creatures are intrinsically superior to the clunky looking water bots.