21. The backs of the ears are black, with white spots ( ocelli ). 22. Giant clams ( Tridacna ) have ocelli that allow light to penetrate their mantles. 23. These appear to grow in rows which are inserted between existing rows of ocelli . 24. They also have a swollen forehead, large compound eyes, and three ocelli . 25. Ocelli are present and form an equilateral triangle.26. Their vision relies on various combinations of compound eyes and pigment-pit ocelli . 27. Its ocelli ( simple eyes ) are well defined and colored a dull yellow. 28. In some species, there are simple light-sensitive ocelli associated with the brain. 29. Unlike most primitive insects, the ocelli between the dorsal portions of the compound eyes. 30. In front of the ocelli is an additional organ that probably functions as a chemoreceptor.
