by macowell
The glass squid is a master of luminous disguise. Unlike the many species that use bioluminescence as an attention-grabbing beacon, this animal uses light as a cloak to evade prying eyes.
Aside from its opaque eyes and the polka dot-like chromatophores (pigmented cells that aid in camouflage) that cover its body, the glass squid is completely transparent. The chromatophores are not an issue, but the opaque color of its eyes can be a dead giveaway. Many species hunt for prey by scanning the water column above them, looking for any telltale silhouettes that might signal the presence of their next meal.
To confound its potential predators, the glass squid makes use of two U-shaped light-emitting photophores located at the base of its eyes: the lights cancel out the shadows cast by the opaque eyes. The effect of this strategy, called counterillumination, is to break up the squid’s silhouette by mimicking the intensity and color of downwelling light from the surface.
The Sparkling Enope Squid is found in the Western Pacific ocean at depths of 600 to 1200 feet and exhibits bioluminescence. Each tentacle has an organ called a photophore, which produces light. By flashing these lights, the Sparkling Enope Squid can attract little fish to feed upon. The Sparkling Enope Squid is the only species of cephalopod in which evidence of color vision has been found. While most cephalopods have only one visual pigment, firefly squid have three, along with a double-layered retina. These adaptations for color vision may have evolved to enable firefly squid to distinguish between ambient light and bioluminescence. The Sparkling Enope Squid measures about 3 inches long at maturity and dies after one year of life.
A bioluminescent squid
The Sparkling Enope Squid (Watasenia scintillans), also known as the Firefly Squid. Each of its tentacles has an organ called a photophore, which produces light. By flashing these lights, the Sparkling Enope Squid can attract little fish to feed upon… The Sparkling Enope Squid measures about 3 inches long at maturity and dies after one year of life.
(via redsassafras)
Lolinginid squid (Sepioteuthis lessoniana)
Sepioteuthis lessoniana
Bigfin reef squid
Sepioteuthis lessoniana
Sepioteuthis lessoniana (Bigfin reef squid)
The squid Abraliopsis has small light organisms underneath its body. These are used for counterillumination, or masking its silhouette by matching the light coming from above. This picture is one of the few on these pages showing actual bioluminescence.
