{"id":7817,"date":"2019-05-22T16:00:58","date_gmt":"2019-05-22T16:00:58","guid":{"rendered":"http:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/egg-tooth_-or_carbuncle\/"},"modified":"2019-05-22T16:00:58","modified_gmt":"2019-05-22T16:00:58","slug":"egg-tooth_-or_carbuncle","status":"publish","type":"post","link":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/egg-tooth_-or_carbuncle\/","title":{"rendered":"Egg-tooth (or carbuncle)"},"content":{"rendered":"<p>A hard tooth-like projection on the top of the beak of embryonic birds or from the upper jaw of pre-hatchling crocodiles, tortoises and turtles (see figure below) that is used to cut the egg membrane and break open the shell so that the animal can hatch. There is a specialized hatching muscle at the back of the neck as well as stereotyped movements of the head and the legs that also assist in release from the egg. &nbsp;Once hatching is complete, the egg-tooth drops off, the movements disappear and the neck muscle begins to shrink. &nbsp;All are examples of ontogenetic adaptations, while the loss of the egg-tooth and the disappearance of the hatching movements constitute qualitative regressions, with the atrophying neck muscle perhaps being an example of a quantitative regression in development.&nbsp;<\/p>\n<p style=\"text-align: center;\" class=\"\">\n<p><img decoding=\"async\" src=\"..\/wp-content\/uploads\/2019\/05\/image027.jpg\" \/><\/div>\n<\/div>\n<p style=\"text-align: left;\" class=\"\">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Chick embryo, 10 days incubation. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Newborn crocodile.<\/p>\n<p>See <a href=\"ontogenetic_adaptation\">Ontogenetic adaptation<\/a>, Qualitative and quantitative regressions<\/p>\n<p><\/p>\n<p><\/p>\n<p><\/body><\/html><\/p>\n","protected":false},"excerpt":{"rendered":"<p>A hard tooth-like projection on the top of the beak of embryonic birds or from the upper jaw of pre-hatchling crocodiles, tortoises and turtles (see figure below) that is used to cut the egg membrane and break open the shell so that the animal can hatch. There is a specialized hatching muscle at the back &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/egg-tooth_-or_carbuncle\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Egg-tooth (or carbuncle)&#8221;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[2],"class_list":["post-7817","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-glossary","entry"],"_links":{"self":[{"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/posts\/7817","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/comments?post=7817"}],"version-history":[{"count":0,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/posts\/7817\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/media?parent=7817"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/categories?post=7817"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/tags?post=7817"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}