Marrella Facts for Kids

This article is about Marella (disambiguation). For other uses, see Marrella (disambiguation).

Quick facts for kids Marrella Temporal range: 510–505Ma PreЄ Є O S D C P T J K Pg N ↓

Fossil lectotype of Marrella, USNM PAL 57674

Life reconstruction of Marrella
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	†Marrellomorpha
Order:	†Marrellida
Family:	†Marrellidae
Genus:	†*Marrella* Walcott, 1912
Species:	†M. splendens
Binomial name
†Marrella splendens Walcott, 1912
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Marrella is an extinct genus of tiny sea creature. It belongs to the arthropod family, which includes modern crabs, spiders, and insects. It lived during the Middle Cambrian period, more than 500 million years ago. Scientists have found tens of thousands of these fossils in the famous Burgess Shale in Canada. Some rarer pieces were also found in rocks from China.

The Discovery of the Lace Crab
- Finding the First Fossil
- A One-of-a-Kind Creature
What Did Marrella Look Like?
- Head Spines and Glowing Colors
- Swimming Legs and Feathery Gills
Life on the Ocean Floor
Where Fossils Are Found
Images for kids
See also

The Discovery of the Lace Crab

Finding the First Fossil

In 1909, a scientist named Charles Doolittle Walcott explored the Canadian mountains. Marrella was the very first fossil he found there. He named it after John Edward Marr, a British rock expert from Cambridge University. Walcott nicknamed it the "lace crab" because of its delicate shape. At first, he thought it was an unusual trilobite.

A One-of-a-Kind Creature

Later, in 1971, paleontologist Whittington studied the fossil carefully. He realized it was not a trilobite, a crustacean, or a chelicerate like a spider. Instead, it was an entirely unique member of the group Marrellomorpha. Along with strange fossils like Opabinia and Yohoia, it proved that ancient ocean life was full of weird and wonderful forms.

What Did Marrella Look Like?

Marrella splendens by Haug et al. 2012
Top left– dorsal view on a rendered 3D model
top right and centre right– micrographs under polarized light
top right – well preserved specimen USNM 83486f with the exopods in a "rusty" preservation (cf. García−Bellido and Collins 2006)
bottom left – stereo image of specimen USNM 139665. Exopods of preceding limbs are super−imposing each other, separated by a thin layer of sediment
bottom right – detail of specimen ROM 56766A in "rusty" preservation. Here the spines on the lateral side of the exopod ringlets are well preserved
centre right – one of the smallest specimens of M. splendens USNM 219817e that possesses preserved appendage remains Black bars for centre right image = 0.6mm, rest = 1mm

Head Spines and Glowing Colors

Marrella was very small, usually less than an inch long. It had a hard head shield with two pairs of backward-curving spikes. These spikes might have had an iridescent shine that flashed colors like a rainbow. The creature had no eyes, but it carried long antennae covered in tiny hairs called setae to feel around in the dark water.

Swimming Legs and Feathery Gills

The body was split into many tiny segments. Each segment held a pair of two-branched limbs. The lower branch, or endopod, had tiny walking claws. The upper branch, or exopod, worked as a feathery gill for breathing underwater. At the end of its body sat a tiny tail called a telson. One rare fossil even shows the creature in the middle of moulting its old skin!

Life on the Ocean Floor

Marrella lived near the muddy ocean floor. It paddled through the water using a lively backstroke motion. Its large head spikes helped keep it steady while swimming and protected it from hungry predators. Scientists believe these little animals were filter feeders. They brushed floating bits of food out of the sea with their feathery limbs and passed the meal straight to their mouth.

Where Fossils Are Found

This tiny animal is the most common fossil in the Canadian Burgess Shale. Over 25,000 specimens have been collected from these ancient rocks, especially in the Phyllopod bed. Older pieces have also turned up in the Kaili Formation and Balang Formation of China, showing that these little swimmers once drifted through seas across the globe.