http://www.seaslugforum.net/showall/cratsp1
http://www.sea-slug.com/species/umiusi173.htm
http://www.ne.jp/asahi/kappa-kuri/miyamoto/OSEHOO/umiushi341.html
http://rfbolland.com/okislugs/crat_sp1.html
http://rfbolland.com/okislugs/crat2sp1.html
http://slugsite.us/bow2007/nudwk647.htm
http://www.jaxshells.org/apere.htm
http://www.underwaterkwaj.com/nudi/eolids/e430.htm
http://www.seaslugsofhawaii.com/species/Cratena-sp1-a.html
http://www.nudipixel.net/species/cratena_sp/
http://www.Philippine-Sea-Slugs.com/Nudibranchia/Dexiarchia/Cratena_sp_03.htm
http://www.Philippine-Sea-Slugs.com/Nudibranchia/Dexiarchia/Cratena_sp_04.htm
http://www.Philippine-Sea-Slugs.com/Nudibranchia/Dexiarchia/Cratena_sp_06.htm
http://www.nudibranch.org/Sulawesi Sea Slugs/html/sss-sea-slugs.html
http://tahitinudi.jimdo.com/liste-des-espèces/cratena-sp/
http://tahitinudi.jimdo.com/liste-des-espèces/cratena-sp-2/
http://marliwakeling.jalbum.net/Nudibranchs/slides/Cratena sp. 1.html
http://www.umiushi-zukan.com/eng/list_pic.php?ssw=g&kind_id=460
http://www.umiushi-zukan.com/eng/list_pic.php?ssw=g&kind_id=815
http://www.umiushi-zukan.com/eng/list_pic.php?ssw=g&kind_id=1288
http://www.vibrantsea.net/cratena2286_anilao2013.htm
http://www.vibrantsea.net/cratena3289_anilao2015.htm
http://www.medslugs.de/E/Ind-NW/Cratena_sp_01/Selection.htm
http://www.medslugs.de/E/Pac-NW/Cratena_sp_02/Selection.htm
http://www.medslugs.de/E/Ind-NW/Cratena_sp_03/Selection.htm
http://www.medslugs.de/E/Pac-W/Cratena_sp_04/Selection.htm
http://www.medslugs.de/E/Pac-W/Cratena_sp_05/Selection.htm
http://www.medslugs.de/E/Pac-W/Cratena_sp_06/Selection.htm
http://www.medslugs.de/E/Pac-W/Cratena_sp_07/Selection.htm
http://www.medslugs.de/E/Ind-E/Cratena_sp_06/Selection.htm
http://www.medslugs.de/E/Ind/Cratena_sp_01/Selection.htm
https://www.vibrantsea.net/cratena8200_anilao2019.htm
http://www.medslugs.de/E/Ind-E/Cratena_sp_09/Selection.htm
http://slugsite.us/bow2007/nudwk1326.htm