Odaraia measured about 15cm long and peered at its ocean home through large eyes on stalks. Its body was divided into dozens of segments, with more than 30 pairs of spindly legs.
Encasing it was the so-called taco shell — a tubular shield that folded around odaraia’s body, leaving its head sticking out the front and its tail poking from the back. Many arthropods have this taco-like feature, known as a bivalve carapace, “including living arthropods like ostracods (seed shrimp) and fan shrimps,” Wolfe said.
The carapace folded over Odaraia’s limbs, so it may have been unable to walk on the seafloor, according to the Royal Ontario Museum. Instead, the sea-bug taco likely got around as modern horseshoe crabs do: by swimming upside down.
While its legs may not have been used for walking, they were probably important for snaring food such as smaller Cambrian sea creatures, the researchers reported. When they examined the fossils, they found stiff, hairlike structures called setae lining the animals’ legs. These tiny spines could have trapped food, much as rows of baleen in whales’ mouths filter seawater and trap plankton.
“We think that the spines could interlock between the legs, creating a net that would capture passing prey,” Izquierdo-López said.
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