The adult is the fourth and final stage of a dragon's life cycle. Adult dragons will never die of old age; this is due to the mythology surrounding dragons and have nearly unlimited lifespans. However, you may attempt to kill them, though adult dragons are the most difficult to kill.
Some dragons can have different sprites depending on their gender. This is refered to as dimorphism, or technically sexual dimorphism. Others will use the same sprite for both genders. A further fifth stage in the dragon's life cycle, called Ascendance, is being discussed on the forums as a possible future addition. It is unknown if ascendance will be implemented into Dragon Cave.
Adult dragons and frozen hatchlings are the only dragons that can have descriptions added to them with the Describe tool. You now have the following options for you to perform on your dragon which are accessed from the Actions menu:
Kill: Kill your dragon. There is a limit to the amount of times you can use this action in a certain period of time.
Release: This releases your dragon into the Wilderness. It will lose its name and never be owned by a person again but will still remain alive. This is a more humane way of removing an unwanted dragon from your scroll rather than killing it.
Name: If you have not yet used this feature, it will still be available. This is to give your dragon a name. If you decide you dislike the name, you may change it at anytime and any number of times.
Describe: Give your dragon a description. This description will be added to your dragon's page under their breed description. You can write anything you want concerning your dragon but the description must first be approved by a moderator before it can appear on your dragon's page (this will happen over time).
Breed: Breed your dragon with another dragon, producing up to four eggs. Recent updates have led to a maximum of one egg being produced if any, except for Holiday dragons in their respective seasons.
If the player has an adult dragon with a different gender than the other on his/her scroll, he/she can make the dragons breed to produce a new egg, providing the breeds are both compatible, such as drake x drake or pygmy x pygmy. This new egg will have two new spaces that say "View Lineage" and "Children". When you click "View Lineage" it links you to where you can view all the past dragons that have bred all the way down to the egg recently created. When you look below "Children", you can see all the times the dragon has succesfully bred and made an egg. Their children can also be viewed in the "View Lineage" link.