The blood orange is a variety of orange with crimson, blood-colored flesh. The fruit is smaller than an average orange; its skin is usually pitted, but can be smooth. The distinctive dark flesh color is due to the presence of anthocyanins, a family of pigments common to many flowers and fruit, but uncommon in citrus fruits. Sometimes there is dark coloring on the exterior of the rind as well, depending on the variety of blood orange. The degree of coloration depends on light, temperature and variety.