ecdysozoa

Opsins are the photosensitive proteins in the eye, responsible for converting a photons of light into an electro-chemical signals. Different opsins react to different wavelengths of light, each corresponding to a different band of colour. In humans, the 'visible spectrum' of light (a very anthropocentric term) is covered by three opsins, receptive to red, green and blue wavelengths. Other animals have opsins that are capable of subdividing the 'visible spectrum' and responding to a large number of very specific wavelengths of interest. All in all, the ability to detect light and recognise colour is not the same throughout the animal kingdom.

In this episode, we are joined by Dr James Fleming of Keio University, Japan to discuss the evolution of opsins in the ecdysozoa (the group containing arthropods and a fair few worms). We talk about the fundamentals of light detection and how, using phylogenetics, we are able to tell which colours certain extinct animals were capable of detecting.

It's been quite a week for lobopodians!

First off, we've had the redescription of Hallucigenia by Dr Martin Smith. This enigmatic fossil from the Burgess Shale typifies the difficulty palaeontologists have had in interpreting some of the earliest animals in the fossil record. It has famously been reconstructed upside-down and is now shown to also have been back-to-front too! Dr Smith joins us to tell us about the observations, including some new anatomical characters, that put an end to the uncertainty of the orientation of this animal.

Secondly, there's a older and more heavily-armoured lobopodian from the early Cambrian Xiaoshiba biota of China that we've got the exclusive on. Collinsium ciliosum is described today and we're also joined by one of the lead authors Dr Javier Ortega-­Hernández.