A recent study of the marine hawksbill turtles' stomach contents revealed that sponges constitute a major portion of their diet. Sponge beds are generally protected from predators by their calcium and silica crystals, but these were found in the turtles' digestive systems. These protective structures are called

1.the evidene of the reaction

2.yes

3.yes

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.