Digestive system of humpback whales stretching like an accordion. They allow whales to open their mandible to 90 degrees to gulp water and prey. They expel saltwater through the baleen plates, leaving behind krill and plankton. The whale's tongue plays a vital role in filter feeding, as it is used to push the water out of its mouth while keeping the prey trapped in its baleen bristles. As humpback whales do not have teeth, their food is swallowed whole and travels down the esophagus into the preliminary stomach (known as the forestomach) to be ground. Baleen whales have a multi-chambered stomach, divided into three distinct
Rough-toothed dolphin as few as two to as many as ninety. Such groups are thought to be temporary assemblages, composed of smaller, more permanent groups of two to eight closely related individuals that occasionally join together with others. They have also been reported to school together with other species of dolphin, and with pilot whales, false killer whales, and humpback whales. Rough-toothed dolphins have been reported to bow-ride on a number of occasions, although apparently they do not do so as frequently as many other dolphin species. They do, however, commonly "skim", by swimming with their heads and chin above the surface