Another example of underwater symbiosis. A Bar Jack is shadow feeding with a Stingray. It's easier to feed on small creatures in sediments that have already been stirred up by rays foraging in the sandy bottom. Normally the Jack's body is grayish blue with a dark horizontal bar which runs along the back and down the caudal fin, often accompanied by an electric blue stripe immediately below it. However, the entire body changes to a blackish colour when the fish is feeding near the bottom, in this case shadow feeding above a Stingray.