http://www.ne.jp/asahi/kappa-kuri/miyamoto/OSEHOO/umiushi109.html
http://www.sea-slug.com/species/umiusi238.htm
http://www.umiushi.info/photo_species/photo_splist_eng.php?sopt=0&loc=0000
http://www.h.do-up.com/home/takayan/takapage332.htm
http://www.seaslugforum.net/showall/okenechi
http://www.medslugs.de/E/Pac-NW/Okenia_echinata/Selection.htm
http://www.bluering.org.au/Opisthobranchs-EaglesNest3418.htm
http://www.nudipixel.net/species/okenia_echinata/
http://www.umiushi-zukan.com/eng/list_pic.php?ssw=g&kind_id=151