A dead dolphin, washed ashore at the beach behind Theosophical Society in Adyar, has raised concern among environmental activists. This is the third dolphin to be found dead on the Chennai coast in the past one month. According to Supraja Dharani, chairperson, TREE foundation, it was a Risso's dolphin, a deep sea mammal that is common in the tropical and warm temperate waters. ''When we inspected the carcass, there were pieces of the nylon fishing net embedded on its face. It seems all three that were washed ashore might have died due to injuries after getting caught in fishing nets,'' she said. On February 11, a Risso's dolphin was found at Thirukapatu near Madras Crocodile Bank Trust. On February 21, another one was found dead near Injambakkam. However, researchers suspect it could be due to natural reasons. Another bottle nose dolphin calf was washed ashore at Kanathur Reddy Kuppam on February 28. Risso's dolphin has a distinctive beakless head shape and grows up to 12.5 feet long and weighs around 300-400 kgs RISSO'S DOLPHIN: FACT Risso's dolphins have a distinctive head They grow up to almost 12 feet in length They weigh between 300 and 400 kg Risso's dolphins are found in tropical areas You can find them in the Mediterranean and the Red Sea, but not in the Black Sea Their favourite food is squid This was the third dolphin found on Chennai's coast within a month At times, Risso's shift locations based on the availability of squid On February 11, a dead dolphin washed ashore at Thirukapatu near Madras Crocodile Bank Trust in Vadanemeli village Another dolphin was found in a decomposed state near Injambakkam on February 21