In his book Wonderful Life the late Stephen Jay Gould, former professor in the Department of Organismic and Evolutionary Biology at Harvard, popularized the “weird wonder” stem-group arthropods Opabinia and Anomalocaris, discovered in the Cambrian Burgess Shale, turning them into icons in popular culture. While the “terror of the Cambrian" Anomalocaris – with its radial mouth and spiny grasping appendages – is a radiodont with many relatives, the five-eyed Opabinia – with its distinctive...

A new study in Nature Communications describes the exceptionally preserved nervous system of the soft-bodied euarthropod Mollisonia symmetrica from the mid-Cambrian Burgess Shale in British Columbia.

Mollisonia symmetrica is a member of a relatively inconspicuous group of euarthropods knows as mollisoniids, which have a simple dorsal exoskeleton consisting of a head shield, multisegmented trunk, and a...

Fish move not just by swimming but also by jumping, burrowing, walking, and flying. Many species though move by undulating their body and caudal fin (the tail fin that is used for propulsion). These body-caudal-fin (BCF) swimmers, as they are called, exert force against the surrounding water to support and move their body in an undulating motion. Traditionally, these fishes were classified based on key morphological traits and then grouped into four expected swimming modes based on four model species: eel, trout, mackerel, and tuna. But do all fish swim in certain ways based on this...

Three-banded panther worms are an incredibly impressive marine animal. Known scientifically as the acoel worm named Hofstenia miamia, these tiny animals that grow to only 500 micrometers can perform one of the greatest feats in the animal world, whole-body regeneration.

Remove Hofstenia miamia’s tail and it will grow another. Remove its head and another one, including everything from a mouth to the brain, will grow in its place. Cut the worm in three separate pieces and within eight weeks there’ll be three fully formed worms. Their power of...