Scientists are pretty sure that porpoises do not do this, and some think this may be due to structural differences in the porpoise’s blowhole. Firstly, let’s accept a basic reality - WHEN a whale or a dolphin intercedes to save a drowning person or to protect a person in the water from a menacing shark, we are likely to hear about it. Researchers are baffled at the brutal behavior, as porpoises throughout Cardigan Bay are being systematically attacked by dolphins. Why have dolphins declared war on porpoises in Wales' Cardigan Bay? Scientists say there has been a dramatic increase in dolphin attacks on harbor porpoises along the California coast over the past few years, including an attack Wednesday off Half Moon Bay. It said scientists have always known that dolphins attack porpoises but the frequency of recent attacks is a real puzzle. When they don’t, … Bottlenose dolphins and harbour porpoises do not prey upon … It has been documented with videos that they like to bully and hurt baby porpoises. Many think of dolphins as these beautiful sweet creatures, but they do attack and kill porpoises. Attacks by dolphins on porpoises have been investigated in several scientific papers. Dolphins are also more talkative than porpoises. Dolphins and porpoises … They can and do cause serious injury to humans and have killed in the past.’ It is not known exactly why dolphins attack humans or large animals like porpoises as, unlike sharks, they do … Why do bottlenose dolphins attack harbour porpoises? They are usually in groups so sharks do not try to attack them but, humans catch thousands of dolphins in a year but, dolphins are not endangered. Dolphins make whistling sounds through their blowholes to communicate with one another underwater. The group told swimmers: ‘Do not confuse the shape of their jawline with a smile.