Brittle Star

Brittle Star, Ophiura graysonensis [Del Rio Formation/Lake Waco Spillway/McLennan County, TX]

The class Ophiuroids is a large group of echinoderms which include the basket stars, Euryalida, and the more familiar brittle stars, Ophiurida. Although similar in appearance, they are not related to starfish which belong to the class Asteroidea. The brittle star has a central, disk-shaped body with long, flexible arms. In order to move, the brittle star wriggles its arms resulting in gliding movement reminiscent of snakes. As the common name implies, brittle stars are fragile, but can replace lost limbs. Although early members of Ophiuroids appeared during the Ordovician Period 500 million years ago, the still extant genus Ophiura is of the more recent Cretaceous Period 145 million years ago. Whole fossils of brittle stars are rare as they rapid fall to pieces after death due to their fragile nature.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.