Is that a testes or an iridescent stripe? A female squid's male-like true colors
During his time in Daniel Morse's lab at the University of California Santa Barbara, USA, PhD student Daniel DeMartini has seen many Doryteuthis opalescens squid pass through the lab's doors. These squid provide DeMartini with a steady supply of the iridocyte cells that are responsible for the squid's shimmering opal-like markings. Iridocytes are found in many cephalopods, but what makes those of D. opalescens so special is their ability to adapt and produce a rainbow of different colours from the same cell. Most iridocytes are found in patches across the squid's body but DeMartini recalls: 'We started to notice that some squid had bright iridescent rainbow stripes underneath their fins. Sometimes most of the squid in a batch would have them, sometimes none. After a while we started to realise the rainbow stripes were only seen in the females.' So after a few years of observing this, DeMartini decided to...