The head of the National Wildlife Federation says he has seen a huge number of dead jellyfish along the beach on an island at the southern end of the Mississippi.

Larry Schweiger says his team will go back out Monday to take tissue samples to see if the oil spill caused their deaths.

Schweiger says it's not uncommon to see jellyfish floating dead during high winds, but the number of dead found so far is beyond normal.

At least 20 sea turtles have been found dead over the weekend along a 30-mile stretch of Mississippi beaches but wildlife officials can't say with certainty the turtles died as a result of the oil spill. They won't know more until necropsies are performed on Monday.