Opabinia

Opabinia reconstruction, from http://www.coe.uga.edu/~pkeck/ediacara/pics

 

Feeding

A primitive arthropod closely related to Anomalocaris this creature has a hose-like structure, called a proboscis, which extends in front of its body. As opabinia swims along the sea floor the proboscis is used to rapidly stir up the sea floor sediment. At the end of this peculiar structure is an even stranger, grasping claw that is used to seize worms and other prey. Opabinia then folds back the proboscis to bring the food to its mouth on the underside of its head. The proboscis could also have been used to obtain prey from within burrows.

What Opabinia Looks Like

The body of Opabinia, excluding the proboscis, is approximately 4 to 7 cm. in length. On the top of the head are five large eye structures. Its trunk is divided into 15 segments each with a pair of hanging lateral lobes that are overlaid with gills. The lobes are thought to enable Opabinia to swim near the sea floor. At its posterior end three pairs of flaps extend upward forming a fan like tail that could have been used to stabilize the animal as it swam.

Classification

Walcott had identified Opabinia as a branchiopod crustacean, but it lacks traits characteristic of this group. Later Opabinia was considered by many to be similar to the trilobites, but this was based on the misinterpretation that the lateral lobes were extensions of a dorsal carapace, which is like the pleurae of trilobites.

Of the Burgess Shale fauna that did not fit easily into any known major group, Opabinia was the first to be redescribed as part of an investigation starting in the 1960’s. Harry Whittington believed that Opabinia was related to an ancestor that gave rise to annelids and arthropods. The classification of Opabinia is still uncertain.

See Opabinia in a color reconstruction at

view an animated reconstruction at http://homepage1.nifty.com/burgess/aaj.html

or http://homepage1.nifty.com/burgess/opl.html