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How does an egg tooth help birds and reptiles hatch?
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birth
Sequential changes in the position of the child during labour.
An egg tooth is a specialized, hard structure used by the young of many egg-laying species to break through the eggshell and escape at hatching.1
While the specific form varies by species, the function remains consistent:
- Birds: Hatchlings possess a sharp, horny tubercle—often called an egg tooth—located on the tip of the upper beak. The bird uses this structure to break the hard shell, allowing it to emerge.234
- Reptiles:
- In lizards and snakes, the egg tooth is a true premaxillary tooth that projects forward from the mouth to cut through the shell and amniotic membranes.15
- Turtles, crocodilians, and tuatara utilize an analogous, horny pointed structure called a caruncle on their snout to slice through the membranes and shell.15
In all these cases, the structure is temporary; it is used specifically for the hatching process and is typically shed or lost shortly after the animal successfully emerges from the egg.1