Sea Urchins

The film offers a close-up examination of sand urchins and rock urchins. At the seashore, a man digs up a sand urchin, and the camera closely observes the creature before he returns it to the sand, where it quickly burrows out of sight. The urchin's intestines extract nutrients from the sand. Through magnification 200,000 times normal size, the spines of a rock urchin are seen with suckers at their ends; a drawing explains their function. A sea urchin moves toward a rock, and the footage reveals its three-fingered jaws—pedicellaria at the ends of flexible stems—that take in algae and other small particles. The film also shows cilia less than 0.001 mm in length, whose constant motion creates whirlpools. Back on the shore, the setting sun is observed. Occasional French titles indicate what to focus on.