Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Transmitted light images of an adult pen. (A) Unpolarized, transmitted light illumination of a dried pen reveals a transparent combination of chitin and protein. (B) Polarized light illumination of the pen reveals a great degree of birefringence (colored regions) along the long axis of the pen. The inset shows an illustration of an adult D. pealeii from the dorsal view with the same orientation and with its pen colored black.
