Opabinia

Opabinia is an extinct genus of stem-group arthropod found in the Middle Cambrian Burgess Shale Lagerstätte of British Columbia, Canada. Only one species, Opabinia regalis, is known.

Description: Opabinia was a soft-bodied animal, approximately 4-7 centimeters in length. It possessed a distinctive morphology characterized by several unique features. The most prominent of these was a forward-facing proboscis, or nozzle, terminating in a claw-like structure, presumably used for grasping food. It had five eyes situated on stalks on its head, and a segmented body with lateral lobes along its sides. These lobes likely aided in swimming. The tail was fan-shaped and composed of three segments. Its mouth was located underneath the head, behind the proboscis and facing backwards.

Discovery and Significance: Opabinia was first described by Charles Walcott in 1912 based on a handful of incomplete specimens. Walcott initially classified it as a crustacean. However, a more complete specimen discovered by Harry Whittington and his team in the 1970s revolutionized our understanding of the animal. Whittington's re-description, published in 1975, revealed the unique combination of features that defied easy classification within known animal phyla.

Opabinia is significant because it highlights the diversity of life during the Cambrian explosion, a period of rapid evolutionary diversification. Its unusual anatomy fueled debate about the relationships between early arthropods and other animal groups. The creature demonstrated that early animal evolution experimented with body plans that have since disappeared. Opabinia is now generally considered a stem-group arthropod, representing an early stage in the evolution of the arthropod lineage but not directly ancestral to any living group. It provides valuable insights into the evolutionary processes that shaped the animal kingdom.