{"id":969,"date":"2014-05-04T22:24:29","date_gmt":"2014-05-05T05:24:29","guid":{"rendered":"http:\/\/illustratescience.wordpress.com\/?p=969"},"modified":"2021-03-28T20:57:35","modified_gmt":"2021-03-28T20:57:35","slug":"why-8-tentacles","status":"publish","type":"post","link":"https:\/\/illustratescience.com\/?p=969","title":{"rendered":"Why 8 Tentacles?"},"content":{"rendered":"
\"Giant<\/a>

Giant Pacific Octopus by Krista Anandakuttan copyright 2008, ink sketch painted in digital media<\/p><\/div>\n

Why 8 tentacles? Exactly.<\/p>\n

Sometimes a question is just really good. Recently while giving a demonstration of science illustration techniques in a natural history museum, a visitor asked me this question. I quickly reassured the asker that no, this was not a case of spider evolution. In fact I quickly drummed up everything I knew about extant cephalopods and even recalled the body plan of the hypothetical ancestral mollusk… yet slug-like ancestry, shell evolution, the appearance of tentacles, and loss of shells; mental images of nautilus, cuttlefish, squid and octopus– nothing yielded the answer.<\/p>\n

So it’s a good question, and I looked it up. Embryology… 18 tentacle buds…fusion in development… 10 tentacles vs 8…. And finally, the sentence: “…ten-armed squids, and eight-armed octopus. What happened? We don\u2019t know… Obviously, what we need is more octopus embryology!”<\/p>\n

I did learn one tangential thing, and that is the distinction between tentacles and arms: tentacles have no suckers or suckers only near the ends, while arms have suckers throughout.<\/p>\n

So I could deflect the question and look smart (and annoying) next time:<\/p>\n

“Why do octopuses have 8 tentacles?”<\/p>\n

Me: “They don’t have tentacles they have arms.”<\/p>\n

Here’s a link to that article:<\/em><\/p>\n

http:\/\/scienceblogs.com\/pharyngula\/2007\/07\/30\/cephalopod-development-and-evo\/<\/a><\/p>\n

and the Art of Nature science illustration exhibit, at the<\/em> Santa Cruz Museum of Natural History\u00a0<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Why 8 tentacles? Exactly. Sometimes a question is just really good. Recently while giving a demonstration of science illustration techniques in a natural history museum, a visitor asked me this question. I quickly reassured the asker that no, this was not a case of spider evolution. In fact I quickly drummed up everything I knew […]<\/p>\n","protected":false},"author":1,"featured_media":123,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[2,7],"tags":[27,93,116,132,135,150,152,174],"class_list":["post-969","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-classes-and-demonstrations","category-science","tag-biology","tag-marine","tag-octopus","tag-questions","tag-research","tag-science-2","tag-science-illustration","tag-tentacles"],"jetpack_featured_media_url":"https:\/\/illustratescience.com\/wp-content\/uploads\/2012\/03\/science_giant-pacific-octopus.jpg","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/illustratescience.com\/index.php?rest_route=\/wp\/v2\/posts\/969","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/illustratescience.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/illustratescience.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/illustratescience.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/illustratescience.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=969"}],"version-history":[{"count":4,"href":"https:\/\/illustratescience.com\/index.php?rest_route=\/wp\/v2\/posts\/969\/revisions"}],"predecessor-version":[{"id":2767,"href":"https:\/\/illustratescience.com\/index.php?rest_route=\/wp\/v2\/posts\/969\/revisions\/2767"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/illustratescience.com\/index.php?rest_route=\/wp\/v2\/media\/123"}],"wp:attachment":[{"href":"https:\/\/illustratescience.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=969"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/illustratescience.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=969"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/illustratescience.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=969"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}