#pirania

Odaraia alata, (yet another) strange arthropod of the Burgess Shale.

Unlike many of the 'weird wonders' of the Burgess like Hallucigenia or Opabinia, Odaraia was quickly identified as an arthropod (although its precise position remains unclear) but what sets it apart is its completely unique functional morphology: in addition to a very unusual telson with three flukes (quite reminiscent of the tail of a plane), Odaraia had a bivalved carapace that almost completely enclosed its body (Briggs & Whittington, 1981), like a living burrito with many legs.

Since the legs were unable to reach out beyond the shield, Odaraia must have spent its life swimming (possibly on its back like a fairy shrimp, based on its center of gravity), using its legs to create currents to guide food particles into the shield space and towards the mouth; the tail flukes likely assisted in stabilizing and steering. The whole animal was about 15 cm long (Briggs & Whittington, 1981).

In the background are Pirania muricata sponges, contemporary to Odaraia and also found in the Burgess Shale (Walcott, 1924).

References and notes about the reconstruction: